Re: revija ATV

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Moderator: s55o

Re: revija ATV

OdgovorNapisal/-a s58ru » 01 Jun 2023, 07:16

TV Rptrs Rptr-132.doc ( 5/31/23, kh6htv) p. 1 of 11
Boulder Amateur
Television Club
TV Repeater's
June, 2023
issue #132
BATVC web site:
ATN web site:
Jim Andrews, KH6HTV, editor -
Amateur Television
at Dayton Hamvention
Dave, AH2AR, DARA, Dayton, Ohio
From Left to Right: Art WA8RMC, Rick KK4LW, Pete N8KKY, Live and in Digital Color, on
the TV Monitor is Bill W8CWM, William WB8YIF, and the venerable N3BFZ
TV Rptrs Rptr-132.doc ( 5/31/23, kh6htv) p. 2 of 11
For the first time in a number of years, nearly perfect weather was experienced at Hamvention 2023.
Aside from a night rain shower that dispersed a half hour before the gates opened, very mild
temperatures appeared. Maybe moving the Hamvention to Xenia finally broke the Dayton curse! The
ATN booth drew in a large number of hams interested in ATV. Like last year, the ATV booth provided
a live cross-link ATV demonstration, along with several different ATV-related projects displayed on the
table. The crosslink consisted of a DVB-T transmitter (HV-310) transmitting on 1280 MHz, QPSK at 2
MHz bandwidth. A Jim Andrews, KH6HTV 23cm amplifier (Model 23-11A) was being used as the
intermediate driver, at reduced output, for the W6PQL model XRF-286 amplifier to provide a final
output of 50 watts. This 23 cm transmission was linked to the W8BI ATV repeater in Huber Heights
Ohio. The 21 mile path was then crosslinked back to the Hamvention ATV booth via a 70cm DVB-T
transmitter at the repeater site on 428 MHz, QPSK, also using 2 MHz bandwidth. At the ATN booth, I
was using a KH6HTV, 70cm preamp and a Hi-Des model HV-110 receiver tuned for 428 Mhz. It was
in line with a cavity for reception of the W8BI ATV repeater.
Along with the crosslink demo, W8CWM, Bill McCoy, participated at his home QTH in Englewood
Ohio, by providing an ATV repeater link demonstration. Bill couldn’t attend Hamvention this year,
however, his “virtual presence” through the ATV repeater helped showcase digital ATV from 35 miles
distance throughout the three days of the show. Of particular note was that on Sunday, a 70cm band
opening occurred that appeared on the ATV repeater link. The ATV repeater was re-transmitting
W8URI’s 70cm analog ATV signal through for all to see at the ATN booth. This constituted an
approximate 80 mile link between the DARA repeater site and Bill Heiden’s location in Mt Giliad,
Crosslink transmitter on 23cm. The demo consisted of a HiDes HV310 transmitter, a Jim
Andrews 23-11A amplifier, an XRF-286 Amplifier, a SOLA 28 VDC 10 Amp power supply, a 13.8
VDC power supply and a Bird wattmeter with a 100 watt element. This equipment was used for
the live demo that was operating for the three days during Hamvention
TV Rptrs Rptr-132.doc ( 5/31/23, kh6htv) p. 3 of 11
Crosslink antennas outside the MAXIM 1 Building’s door. That is a Directive Systems loop Yagi
growing out of K8FIX’s head!
Along with the active crosslink transmitter hardware on display and the W8BI ATV repeater reception,
the following projects were also displayed at the ATN booth:
K0PFX, Mel Whitten provided his TX/RX Interface
integrated with a 10 watt amplifier for the ATN table top
display. During Hamvention 2023’s ATV forum, he provided
additional information about this project. Mel Whitten has
also created helpful, very detailed comprehensive
documentation on the construction of this interface. It can be
found on his website:
Two separate extremely portable “self-contained”
maintenance DVBT receiver-monitors were on
display that I (AH2AR) had brought in for the
TV Rptrs Rptr-132.doc ( 5/31/23, kh6htv) p. 4 of 11
WA8RMC, Art Towslee provided his Versa-Tuner
digital receiver prototype that he has been working
on. Shortages of Rasberry Pi’s and some software
work has held up the production start as he had
spoken about during the ATV forum. Art’s and
Mel’s ATV discussions during the ATV Forum
about these ATV projects can be found on YouTube
at the following link:
Please blame me (AH2AR) for recording the ATV
forum in Portrait Mode instead of Landscape mode.
I must say that the video does look great on smart
Also displayed was an AH2AR project that uses the
TC70 series A5 transceivers as a host interface that
provides T/R switching, 3 watts of RF power
output, and additional DVB-T receiver gain for the
HiDes HV series transmitter-receivers. The
modification requires only nine components and
once the mod is installed, it does not lose
functionality of the analog (A5) transceiver. Here is
the article:
Disaster struck when we found out that the ATV dinner was excluded from the Hamvention Program.
Since the ATV Dinner was scheduled for Friday and the ATV forum was scheduled for Saturday, we
were unable to let everyone know that the ATV Dinner was still on the docket. To make matters even
worse, a number of ATV anchors (Bill Brown WB8ELK and Mike Collis WA6SVT were unable to
attend due to granddaughter / work commitments. The only good thing that became of this was that of
the eight ATVers who attended, 50 percent walked away with door prizes!
TV Rptrs Rptr-132.doc ( 5/31/23, kh6htv) p. 5 of 11
ATV Dinner attendees… This actually looks like a large
number of ATVers, however, there is a mirror in the
background. In attendance was KE0VR, N3BFZ,
AH2AR (taking the photo in the background!)
W0BTV - DATV Repeater
is Back on the Air !
Finally !
Photo at right is Don, N0YE, assistant trustee for W0BTV
proudly proclaiming that the Boulder, Colorado ATV repeater
is once again operational. This time, it actually works !
Date: 24 May. Our first attempt on the 19th to reinstall the
repeater ended up in failure when the 70 cm transmitter failed
while we were on-site. Subsequent bench test showed that
the Hi-Des model HV-100EH modulator had failed and was
not putting out any RF. It was replaced with another HV-100.
Input Frequencies are: 1243 MHz (6 MHz BW), 441 MHz
(6 MHz BW) and 439 MHz (2 MHz BW) - all DVB-T
Output Frequencies are: 423 MHz (6 MHz BW), DVB-T
and 5.905 GHz, FM-TV (24/7 beacon)
TV Rptrs Rptr-132.doc ( 5/31/23, kh6htv) p. 6 of 11
Signal Reports for W0BTV
With our newly, re-installed and modified DATV repeater, we are now in the performance testing
mode. We want to publish everyone's experience (both good and bad) with how well it is performing.
The repeater uses Hi-Des receivers which have a nice feature of On-Screen-Display (OSD) of
frequency/bandwidth, incoming call sign, received signal strength in dBm and signal/noise in dB. We
have the OSD feature permanently turned on. Thus this data is always displayed on the repeater
image. Thus each user can determine how strong a signal he/she is putting into the repeater and also
it's s/n quality. Plus for those ATV hams using Hi-Des receiver's at home, they can also use the OSD
to determine how well they are receiving W0BTV's signal at their qth.
It should be noted that each of the three Hi-Des receivers at the repeater have a significant offset in
their reading that needs to be corrected before reporting the actual signal strength at the repeater's
antenna input connector. Not at the antenna, but at the repeater rack in the radio room. For the
1243/6 MHz receiver the offset is +40dB. For the 441/6 MHz receiver the offset is +25dB. For the
439/2 MHz receiver the offset is +9dB. For example, if the 439/2 MHz receiver is displaying an S
meter reading of -63 dBm, the real input to the antenna input connector was:
-63 dBm (OSD) - 9 dB (offset) = -72 dBm
The repeater's sensitivity was measured in closed circuit, bench testing using "normal" digital
parameter QPSK signals ( 8K FFT, 5/6 code rate (i.e. FEC), 1/16 Guard ) For 6 MHz BW, the video
resolution was set to 1080P and 5.5 Mbps. For 2 MHz BW, the video resolution was set to 480P and
1..5 Mbps. With these settings, on the bench, the minimun S/N was about 8 dB for P5 picture Q5
audio with no freeze framing. The sensitivities measured under these conditions for keying the
repeater reliably were: 1243/6 MHz = -91 dBm, 441/6 MHz = -87 dBm & 439/2 MHz = -94 dBm
On the bench, with no antenna connected, the corrected, residual noise level displayed by the S meter
was: 1243/6 MHz = -100 dBm, 441/6 MHz = -101 dBm, & 439/2 MHz = -100 dBm
In actual repeater operation with our Diamond X-6000 receive antenna connected we see the following
background, no incoming DVB-T signal, S meter readings:
1243/6 MHz = -102 dBm (-62 dBm displayed)
441/6 MHz = -99 dBm (-74 dBm displayed), but with many peaks much stronger as other RFI signals
come and go. Strongest noted has been -89 dBm (-64 dBm displayed)
439/2 MHz = -100 dBm (-91 dBm displayed), again with many peaks much stronger as other signals
come and go. Strongest noted has been -91 dBm (-82 dBm displayed)
Signal Reports from BATVC Hams:
KH6HTV - Jim From my present, new qth 12 air miles due east of the repeater, I am able to
receive both the 70 cm and 5 cm signals. I am able to put a good signal on 23cm into the repeater. I
also put strong signals in on 70cm (both 6 & 2 MHz BW) but not sufficient to override the background
TV Rptrs Rptr-132.doc ( 5/31/23, kh6htv) p. 7 of 11
RFI. For antennas, I am using Yagis for both 70cm (11dBi) and 23cm (15dBi). Dish (22dBi) for
5cm. DVB-T transmit power is 10 W (70cm) and 3.7 W (23cm).
I receive the 70cm repeater signal at -62 dBm with a perfect 23dB s/n. On 5 cm, I receive the FM-TV
signal P5 with no rfi. For transmitting into the repeater, my signals at the repeater are: 1243/6 MHz
= -81dBm & 17dB s/n; 441/6 = -68dBm with 16dB s/n (but severe freeze framing with RFI); and
439/2 = -71dBm with 15dB s/n (again not useable due to intermittant freeze framing). Conclusion:
439/2 MHz did not cure the RFI problem, at least for me getting into the repeater on 70cm band.
NOYE - Don I am close to the repeater near Fairview High and 1.2 miles distant and line of sight. I
receive very strong signals from both the 70 cm and 5 cm repeater transmitters. My uplink signals are
+34 dBm (2.5 Watts) on 70 cm and +22 dBm (160mW) on 23 cm. The repeater receives them at -51
dBm, 23 dB s/n on 70 cm and -75 dBm, 19 dB s/n on 23 cm. No RFI freeze framing on any of my
transmissions. note: running QPSK on DVB-T, a s/n reading of 23dB is the max. possible and
indicates a perfect, 100% quality picture.
Pete, WB2DVS & Debbie, WB2DVT They live near Arapahoe & Foothills parkway, about 3 miles
from the repeater site in a subburban area with lots of houses and trees. Their antenna situation is
compromised. They use a yagi antenna mounted indoors looking out a west window. They use only
the 70 cm band and transmit with 10 watts. They put a good signal into the repeater on 441 MHz
measuring -64 dBm with 23 dB s/n. But even with 10 watts, there is an occasional freeze framing due
to intermittant RFI.
WA2YUN - Colin Colin lives very close to the repeater. Only 0.6 miles, but his qth is on the same
hillside as the repeater's site on the top of the mesa. Thus he is in a shadowed area. Colin uses the 23
cm input with 3 watts of rf. His signal into the repeater is -78 dBm with 18 dB s/n.
K0HEH - Jack Jack lives just to the east of the university in a residential area with lots of trees.
His view to the repeater is compromised by a large apartment building nearby. He is 2.3 miles from
the repeater. On 23cm with 3 watts he puts a weak -85 dBm signal into the repeater. Sometimes
works, sometimes not. If he uses Steve's repeater he is then able to get into W0BTV fine.
WA0TQG - Steve Steve lives a long way from the repeater, up in the mountains on top of Sugar
Loaf mtn. He is completely shielded from the W0BTV repeater. As a work around, Steve designed
and built his own cross-band 23cm/70cm repeater to enable him to access W0BTV. Steve's repeater is
located at Jack, K0HEH's qth in Boulder which is line of sight from Steve. Using 10 watts and a yagi
antenna at Jack's qth, Steve's repeater gets into W0BTV quite well. On 441 MHz, his signal at
W0BTV is -54 dBm with 23 dB s/n.
K0CJG - Chris Chris lives in the south-east part of the city, near Baseline road and Foothills
parkway. He is 2.9 miles from the repeater. Again, like others he lives in a residential neighborhood
with lots of houses and trees. He runs 3 watts to a loop yagi antenna on 23 cm. Chris reports -- "Hi
Jim -- I made some measurements today for my rig on FULL power (3 watts): Power: -86 to -91 dBm;
s/n = 11-15 dB. My signal is weak compared to past observations on MEDIUM power (1 watt) which
were - Power: -85 to -82 dBm; s/n of 16 – 23 dB. I also dropped out on low power, which used to
give me an OK signal with occasional freeze frames, so my power is low. I see one of the directors on
TV Rptrs Rptr-132.doc ( 5/31/23, kh6htv) p. 8 of 11
my loop yagi is turned almost sideways, so maybe the solar installation guys bumped the antenna
pointing as well. I’ll redo the measurement when I get a chance to get up on the roof to realign the
antenna. On low S meter readings -- I also see a small tree has grown quite a bit this year and heavily
leafed out right in my line of sight to NCAR. I planned on loping it off at the top anyway since it
shades some of my solar panels also. I’m sure a few dB’s are lost in it."
AB0MY - Bill Bill lives in north Boulder on a hilltop, but surrounded by other houses and lots
of trees. He is 4.5 miles north of the repeater. Bill has full capability, including 70cm, 23cm and 5cm
with yagi antennas and max. rf power Bill reports --- "Hi Jim, -- Here are the results of my tests this
evening. 5.9 GHz beacon, ignoring the Wi-Fi interference, I'd give it a P4.5, just seeing a faint ghost.
OSD for repeater's 423/6 output at my location -68dBm, s/n 22dB
My 1243/6 signal at the repeater -73dBm, s/n 23dB using medium power of 1 watt.
My 441/6 signal at the repeater -69dBm, s/n 20dB using medium power of 1 watt.
K0JOY - Ed Ed lives in the mountains, north of Boulder on a ridge line with a great 180 degree
view out on the eastern Colorado prarie. He has a line of sight path to W0BTV. The distance is about
9 miles due north. Ed runs 3 watts on 23cm to a home-built converted 2.4 GHz BBQ grill dish
antenna. Ed says he "sees -79 dBm with s/n of 18 dB into the repeater. With low power (300mW), -
88 dBm and s/n of 9 dB. Readings the same as in the past. All seems good."
W0BTV Required Repairs: We recently had several failures in our
Boulder ATV repeater, W0BTV. We had to purchase several items to replace failed components.
Plus, other items were purchased to modify the repeater to add the 439 MHz / 2 MHz BW receive
capability. These are the items purchased: Hi-Des HV-100EH Modulator ( $415), Hi-Des HV-110
Receiver ($124), RC-832 5.8G FM-TV Receiver ($18), (3) OREI model UHD-PRO102 1in/2out
HDMI Splitters + HDMI cables ($94), Agptek Mini 1080 Digital Media Player ($38), and Intuitive
Circuits model DTMF-8 DTMF Decoder / Relays pc board ($134). The total outlay for repair and
modification came to $823.
SDATV Happy 14th !
San Diego, California ATV --- SDATV Society is 14 years old today! Membership continues to be
very active {23 members ages 12 to 18 and 50 ages from 19 to 79. Our STEM Program continues to
include funding from NASA and the National Science Foundation.
Our Network continues to operate 24/7/365 with no issues in operational status, non interference
operations with our neighbors to the North.
TV Rptrs Rptr-132.doc ( 5/31/23, kh6htv) p. 9 of 11
THOR Broadcasting, Torrance, California ( ) is a great supporter to our
society membership. We thank them for their continued support.
73! Mario, KD6ILO
ATV News from Down-Under
We exchange newsletters with the North East Victoria (Australia) Amateur Radio Club (NEVARC). It
often contains a lot of news about their ATV activities. ( ) The editor, Mick,
VK3CH, is an avid ATVer.
There is a new ATV repeater soon going on the air
from Mt. Anakie, near Geelong. Call sign is
VK3RGL. Input is 1255 MHz, either DVB-S or
DVB-T. Output is 2411 MHz, DVB-T. Robert,
VK3EHT is building the repeater. The latest
NEVARC newsletter, June, 2023 has several
pages in it devoted to the new repeater and also
Mick's work on putting together the necessary kit
to be able to work it from his qth 78 km to the east
in Doncaster, a suburb of Melbourne. VK3RGL
has only undergone some preliminary testing.
They hope to get it on the air later this year, or
possibly early next year.
Mick's home-brew 2.4 GHz down-converter
Jim --- Regarding HDMI:
I have worked with it more for home theater but it is a headache there too.
TV Rptrs Rptr-132.doc ( 5/31/23, kh6htv) p. 10 of 11
There is a pretty good writeup on Wikipedia about it and shows the many versions that it has gone
through so it is important that all devices are compatible with the version used. In addition
manufacturers are not required to implement all features of a version so it is anyone's guess if products
will be compatible depending on features used. Here is a quote from Wikipedia:
"Products are not required to implement all features of a version to be considered compliant with that
version, as most features are optional. For example, displays with HDMI 1.4 ports do not necessarily
support the full 340 MHz TMDS clock allowed by HDMI 1.4; they are commonly limited to lower
speeds such as 300 MHz (1080p 120 Hz) or even as low as 165 MHz (1080p 60 Hz) at the
manufacturer's discretion, but are still considered HDMI 1.4-compliant. Likewise, features like 10 bpc
(30 bit/px) color depth may also not be supported, even if the HDMI version allows it and the display
supports it over other interfaces such as DisplayPort.[92]
Feature support will therefore vary from device to device, even within the same HDMI version."
So unless a manufacturer has certified that two products are compatible (most don't) you just have to
try it and see for yourself as you have found out.
73 de Steve, WA0TQG, Boulder, Colorado
It's been 31 years since I approved ATV/DATV distance records on my website
The principle of the classification is as follows: the QSO will be considered as the world record if the
distance between the two correspondents is greater than the previous approved record. In addition, at
equal distance, the world record will be awarded to those who have used the smallest apparent power to
achieve it.
The approval of a record is not an easy task because the record holders do not always announce their
records to me. I need at least the distance covered, the date and time of the QSO, the standard used
(DVB-T, DVB-S, etc.) and the SR. Then, for each correspondent, I need the callsign, the locator, the
transmission power and the type of antenna as well as proof of reception, a screenshot or a video.
To answer to S58RU who made an 8 km QSO in DVB-T on 24GHz in 2022, I specify that I only
approve distance records, not the first ones (first DATV QSO on 24GHz for example). I also don't
classify the records by standard, SR or other, that would be way too complicated. There is a "DATV"
class, all digital modes (DVB-S, DVB-T, etc.) and SR combined, and an "ATV" class, the old analog
AM or FM standard.
The DATV 24GHz record is currently held by the duo IW9ARO/9H1GB with 186km.
73 de Michel HB9AFO
[editor's note -- A big Thank You to Michel for all his work in compiling these records.]
TV Rptrs Rptr-132.doc ( 5/31/23, kh6htv) p. 11 of 11
CORRESPONDENCE: Jim --- Thanks for adding my name to the distribution list for your
ATV newsletter! We moved to the Portland metro area last month and I have restarted Amateur Radio.
Really interested in ATV, so delighted to find an ATV repeater group here (currently inactive, and
thinking of going digital)
BTW, I authored a few articles for the BATC (back in the day; CQTV edition 190ish, year 2000) - good
to see they're still active.
73, Peter J. Stonard, KN6VSL, ex- G8PJD, Portland, Oregon
Editor's Note: BATC in 2000 -- The chairman then was Trevor Brown, G8CJS and the CQ-TV
magazine editor was Ian Pawson, G0FCT. Years later, in 2013, they went on to start CQ-DATV. An
all electronic, on-line, slick magazine. ( ) It ran for 100 issues.
The last appearing in October, 2021.
W0BTV Details: Inputs: 23 cm Primary (CCARC co-ordinated) + 70 cm secondary
all digital using European Broadcast TV standard, DVB-T 1243 MHz/6 MHz BW (primary),
plus 441 MHz/6 MHz BW and 439 MHz/2 MHz BW
Outputs: 70 cm Primary (CCARC co-ordinated), Channel 57 -- 423 MHz/6 MHz BW, DVB-T
Also, secondary analog, NTSC, FM-TV output on 5.905 GHz (24/7 microwave beacon).
Operational details in AN-51c Technical details in AN-53c. Available at:
W0BTV ATV Net: We hold a social ATV net on Thursday afternoon at 3 pm local
Mountain time (22:00 UTC). The net typically runs for 1 to 1 1/2 hours. A DVD ham travelogue is
usually played for about one hour before and 1/2 hour after the formal net. ATV nets are streamed live
using the British Amateur TV Club's server, via: Select ab0my or n0ye. We
use the Boulder ARES (BCARES) 2 meter FM voice repeater for intercom. 146.760 MHz ( -600 kHz,
100 Hz PL tone required to access).
Newsletter Details: This is a free newsletter distributed electronically via e-mail to
ATV hams. The distribution list has now grown to over 500+. News and articles from other ATV
groups are welcomed. Permission is granted to re-distribute it and also to re-print articles, as long as
you acknowledge the source. All past issues are archived at:
Free advertising space is offered here to ATV hams, ham clubs
or ARES groups. List here amateur radio & TV gear For Sale -
or - Want to Buy ... tr-132.pdf
Prispevkov: 1012
Pridružen: 28 Okt 2004, 21:07

Re: revija ATV

OdgovorNapisal/-a s58ru » 12 Jun 2023, 07:20

TV Rptrs Rptr-133.doc ( 6/10/23, kh6htv) p. 1 of 11
Boulder Amateur
Television Club
TV Repeater's
June, 2023
2ed edition, issue #133
BATVC web site:
ATN web site:
Jim Andrews, KH6HTV, editor -
Advice for Wana-Be Digital ATV Hams
It "Takes Two to Tango!" It is very important to not be an "ATV loner". If you have other ham
buddies nearby also interested in getting into ATV, then get together for face to face meetings to
compare notes, and jointly test out your gear in very close, line of sight, experiments. Plus it can be
very lonely if you have no one else to share your video with. Watching your own signal gets boring
real fast.
Getting into digital amateur TV (DATV) will require considerable $$ investment. It is comparable to
purchasing a new, entry level HF transceiver and accessories. So you need to be prepared to spend
some bucks. The older, analog TV was less expensive, but that gear is rapidly disappearing. Sole
exception is very inexpensive, FM-TV gear for 5.8 GHz.
Success is NOT guaranteed ! Propagation will not be as simple as HF operation. It is UHF and line
of sight, not over the horizon. Plus we run low power ( a few watts) from low antennas. Unlike the
big gun broadcast TV stations with many kilowatt transmitters and high towers. I do know personally
that obstructions in the rf path, like hills, buildings, etc. are deadly to our TV signals. At the higher
microwave frequencies, vegatation, like trees, with moisture suck up our signals. What works with a
2 meter hand-held radio might not work for our ATV. In that case, the laws of physics are fighting
against us in terms of the noise floor for our receivers. The wider bandwidth required for TV means
more noise in the receiver and poorer sensitivity. I don't want to be a "wet blanket", but do want to
warn you in advance that DATV propagation over any significant distance can be "iffy". I have found
that the free, on-line, rf propagation calculator, Radio-Mobile, is an accurate tool for predicting
TV Rptrs Rptr-133.doc ( 6/10/23, kh6htv) p. 2 of 11
whether a particular rf path will work, or not, for our ATV. To learn more about Radio-Mobile, check
out my app. note, AN-33a, "TV Propagation" on my web site:
Also, unfortunately, digital TV is not as simple as the older analog TV. Lots of gottchas in getting the
many digital parameters in the modulator and receiver set properly before we get successful pictures.
Thus vitally important to work with other nearby ATV hams to be assured of compatibility.
Now for your shopping list --- For DVB-T modulators, Hi-Des in Taiwan ( )has
been our preferred supplier for Boulder, CO ATV hams. But there are others also. No matter whose
modulator you buy, it will only put out a very weak, low powered signal of the order of a milliwatt ( 0
dBm). That is enough for testing in your ham shack, or across your basement, but not for going any
further. Then you will need a LINEAR ( emphasis, no class C allowed ! ) rf power amplifier to get
you up to the at least several watts of rf power ( > +30dBm). Not cheap, sorry.
Plus a good outdoor antenna up as high as possible. For antennas -- word of caution -- not all anateur
70 cm antennas work well with ATV. Best to only buy those that have been tried and certified by
other ATV hams. Don't just blindly go buy any 70 cm antenna.
Another Mid-West Band Opening
Saturday, 3 June, 7am
This is an an A5 signal from Charles
Beaner in Morrow County, Ohio passing
through the W8BI repeater in Dayton,
Ohio on its DVB-T output…at 85
The repeater's S meter is reporting a
signal strength of -77 dBm with a perfect
23 dB s/n. Input frequency of 428 MHz
with a 2 MHz band-width photo tnx to Dave, AH2AR
K8FIX Bruce Kobe discussing ATV related
questions from several Hamvention attendees
at the ATN booth.
TV Rptrs Rptr-133.doc ( 6/10/23, kh6htv) p. 3 of 11
FM-TV Demodulator
Circuit Details:
Back in March (issue #126), we discussed the overall
design concepts of an FM-TV demodulator. We promised
to provide more details in later newsletters. This is
derived from the instruction manual written in 2014.
The model 23-5 FM-TV demodulator consisted of a high gain, 70 MHz IF amplifier followed by a
video FM demodulator and a pair of audio FM demodulators. It was intended to be used with a
microwave down-converter with an IF output of 70 MHz. In the May newsletter, issue #130, we
discussed the design of the 70 MHz IF amplifier. In this issue, we will discuss the design of the FMTV
video demodulator and video amplifier. The detailed schematic diagram is shown on the following
IC, U4, is a PLL FM demodulator tuned to 70 MHz. It is a Phillips NE568AN. It is a monolithic
phase-locked loop (PLL) which operates from very low frequencies up to 150 MHz. The NE568A
consists of a limiting amplifier, current controlled oscillator, phase detector, level shift circuit, V/I and
I/V converters, output buffer and necessary bias circuits. It was intended for demodulation of FM
signals with extremely large deviation in systems which required a highly linear output. The typical
application was for satellite TV receivers with a 70 MHz IF. It could demodulate ± 20% deviations
with less than 1% non-linearity. I used Phillips recommended circuit for U4, NE568A. See their data
sheet for details. I used the N suffix version which is a 20 pin DIP package.
U4's output contains both the video signal and also the stereo sound sub-carriers (SSC). The SSCs are
in the range from 5 to 7 MHz. We will discuss the SSC demodulators in a future issue.
TV Rptrs Rptr-133.doc ( 6/10/23, kh6htv) p. 4 of 11
TV Rptrs Rptr-133.doc ( 6/10/23, kh6htv) p. 5 of 11
In the video chain, I first inserted a 13 MHz low-pass filter to remove all remaining 70 MHz IF signal.
Then a 4.8 MHz, Chebyshev low-pass filter was inserted in the video chain to filter off the SSCs. If
there are no SSCs present, this 4.8 MHz low-pass filter can be by-passed with internal jumpers to
achieve a higher video bandwidth of 7.8 MHz with a more Gaussian response and higher video
4.8 MHz Low-Pass Video Filter frequency response. Sweep from 0 to 10 MHz. 5 dB/div & 1
Hz/div. Ignore "glitch" at 0 frequency at extreme left.
A Motorola (now ON Semi) NE592 video amplifier was used for U5. The NE592 is a monolithic,
two stage, differential, wideband video amplifier. It has fixed gains of 100 or 400 and with an optional
external resistor the gain can be set between 0 and 400. I used the N suffix version which is a 14 pin
DIP package. The NE592 was specifically designed for video amp applications such as this.
Video amplifier, U5, has differential outputs. With an internal jumper setting, either positive or
negative polarity video can be selected. The gain of U5 was adjusted with the trim pot, R16. The
video gain was set differently depending upon whether video pre-emphasis was used, or not. The
polarity of the video output from U5 was set via a jumper on the pc board selecting the appropriate
differential output from U5.
The output video driver amplifier, Q1-Q2, was capable of driving a 1 Vptp standard video signal into a
75 Ω load from a 75 Ω output impedance. A de-emphasis filter is on the output of the driver amplifier.
It provides standard CCIR 405-1 de-emphasis for NTSC signals. If the 23-5 is used for PAL video,
then different de-emphasis filter component values are required. If the video signal has not already
had pre-emphasis put on it, then this filter should be bypassed by moving two internal jumpers.
The following photos demonstrate the performance of the composite KH6HTV model 23-1 transmitter
and 23-7 & 23-5 receiver.
TV Rptrs Rptr-133.doc ( 6/10/23, kh6htv) p. 6 of 11
Video Waveform Test Equipment.
Color Bars test signal -- Horizontal Interval -- 2H. Composite video waveform response of a 23-1
FM-TV Transmitter and 23-7/23-5 FM-TV Receiver. No pre-emphasis / de-emphasis used. 4.8 MHz
Chebyshev low pass filter used in 23-5.
TV Rptrs Rptr-133.doc ( 6/10/23, kh6htv) p. 7 of 11
Multi-Burst test signal -- Horizontal Interval -- 2H. Composite video waveform response of a 23-1
FM-TV Transmitter and 23-7/23-5 FM-TV Receiver. No pre-emphasis / de-emphasis used. 4.8 MHz
Chebyshev low pass filter used in 23-5.
Jim Andrews, KH6HTV, Boulder, Colorado
Update on new NBTV hybrid encoder/decoder
I have been very busy over the last few weekends working on software for my NBTV project, as there
has been a number of developments made, as it is now a digital & analog hybrid transmission and
coding system. I have posted the information on the Narrow-bandwidth television association-forum,
last week under the handle of GrantXTV: ... =90#p28580
TV Rptrs Rptr-133.doc ( 6/10/23, kh6htv) p. 8 of 11
I put together a basic program to test out different ways of doing video compression, whereby I read in
a video file and convert it to RGB, then RGB back to video. With the gap in between to plug in
software models for different experiments to see what works and what does not work, before I send out
the bit stream to the modulator for extra processing. The aim is to go with a hybrid approach that is
both digital and analog or somewhere in between. The first stage is the digital compressing that has a
image frame (I) fixed image and a predicted picture (P) made up of parts of each frame from image on
each side. Since I am using analog modulation 65536QAM, or just QAM for short (video and sound),
plus MFSK (data channel), therefore it is not possible to send any forward error correction (FEC), so
the digital compression needs to work with noise, therefore I making fill use of noise reduction and
analog compression / expansion in the modulator and demodulation sections.
As for the hardware design, I am now working on a new modulator using ADC,DAC,FPGA and
SRAM, as lot of the processing is now done in software, make this a lot simpler task to do. This is still
very much a multi-year project as I am working it out as I go, here a image of version one software
I have made a few more updates since then, in the digital video encoder / decoder using Wavalet
processing to enhance the 120 x 96 image up to 240 x 192 at 12.5 pictures per second, made up of a
key and picture frame. Where one date block sends on of each, making up 6.25 date frames, the
modulated on 24 65536QAM carries or QAM for short. At this stage I am only working on the
software, to encode and decode a video signal and I will post some videos within the next few weeks,
highlighting what possible, as this will be a multi year project as I am designing it from the ground up.
73 de Grant, VE3XTV, North York, Ontario, Canada
ATV International QSO Party: Once again, Peter, VK3BFG, in
Melbourne, Australia is organizing his annual ATV QSO party. He has just sent out a notice that it will
be on Friday & Saturday, August 25-26. The USA session is planned for Friday night and the
Australian session for Saturday morning/afternoon. He is looking to drum up interest in many other
ATV groups to participate in it. If intererested, contact Peter directly. ( pcossins at )
Misc. Correspondence:
More Signal Reports on W0BTV:
Hi Jim --- I finally got up on my garage roof this afternoon and trimmed the tree blocking my 23 cm
signal, and also fixed the antenna damage done by the solar guys. I was in the process of peaking up the
pointing when it started raining between here and NCAR so I quit while I was ahead.
Here’s what I’m seeing:
High Power (3 Watts): -42 to -38 dBm, 15 to 23 dB SNR
Med Power (1 Watt): -44 to -46 dBm, 13 to 15 dB SNR
So I’m back in action on medium power. I can probably get a dB or 2 more if I finish peaking up the
pointing when the rain finally stops.
73, Chris K0CJG, Boulder, Colorado
TV Rptrs Rptr-133.doc ( 6/10/23, kh6htv) p. 9 of 11
DATV Flies on a Student Balloon
Jim --- Just wanted to let you know that the model 70-7B amplifier you built for us will be flying on
our student payload on Monday, June 5th at around 10am. If you would like, you are welcome to watch
our livestream of the event:
If you would like any more information, let me know and I'll gladly share. Thank you for all of your
help over the past few months.
Kind regards, Drew, AC3DS, Fairview, PA
Portland, Oregon - ATV
Jim --- Yes, very helpful! I'm going to pass on the encoder I mentioned (it was an eBay find). Going
forward I plan to buy the Hi-Des Tx and Rx for a digital station here.
Not sure if there are any other ATV stations on the air in this area. I'm close friends to the existing
ATV repeater custodians, so working with them is the key to getting their repeater back on track. It was
NTSC Analog (70cms in, 23cms FM out). BTW, as I'm starting from scratch at this QTH I have to
get antenna up and build a conventional Ham station first.
I just got word from the FCC to change my callsign, dropping the "six" (California issued). The new
call is K7GVG to honor my time working for the Grass Valley Group on analog Broadcast equipment.
I have a deep collection of analog SD, NTSC gear that I intend to put to good use in the Ham hobby.
Looking forward to the projects ahead. I'll be reaching out to you for help, and have some content for
your newsletter.
73 de K7GVG, (formerly G8PJD ), Peter J. Stonard, Portland, Oregon
W0BTV Details: Inputs: 23 cm Primary (CCARC co-ordinated) + 70 cm secondary
all digital using European Broadcast TV standard, DVB-T 1243 MHz/6 MHz BW (primary),
plus 441 MHz/6 MHz BW and 439 MHz/2 MHz BW
Outputs: 70 cm Primary (CCARC co-ordinated), Channel 57 -- 423 MHz/6 MHz BW, DVB-T
Also, secondary analog, NTSC, FM-TV output on 5.905 GHz (24/7 microwave beacon).
Operational details in AN-51c Technical details in AN-53c. Available at:
W0BTV ATV Net: We hold a social ATV net on Thursday afternoon at 3 pm local
Mountain time (22:00 UTC). The net typically runs for 1 to 1 1/2 hours. A DVD ham travelogue is
usually played for about one hour before and 1/2 hour after the formal net. ATV nets are streamed live
using the British Amateur TV Club's server, via: Select ab0my or n0ye. We
use the Boulder ARES (BCARES) 2 meter FM voice repeater for intercom. 146.760 MHz ( -600 kHz,
100 Hz PL tone required to access).
TV Rptrs Rptr-133.doc ( 6/10/23, kh6htv) p. 10 of 11
Newsletter Details: This is a free newsletter distributed electronically via e-mail to
ATV hams. The distribution list has now grown to over 500+. News and articles from other ATV
groups are welcomed. Permission is granted to re-distribute it and also to re-print articles, as long as
you acknowledge the source. All past issues are archived at:
Free advertising space is offered here to ATV hams, ham clubs
or ARES groups. List here amateur radio & TV gear For Sale -
or - Want to Buy
- Modulator & Demodulator for Sale
These items were recently
removed from the Boulder,
Colorado, W0BTV, ATV repeater.
In good working order. They are
ideal for someone wanting to
assemble a 70 cm, analog ATV
Modulator Demodulator / Receiver
The Pico-Macom model MPCM45 modulator is a fixed channel unit working on only Ch 57, 421.25
MHz. It puts out a perfect vestigal, upper-sideband TV signal. (VUSB-TV). It also includes the 4.5
MHz sound sub-carrier. The rf output is at the milli-watt level. It thus needs to be followed with an rf
linear power amplifier. The W0BTV repeater used a KH6HTV model 70-9 amplifier to boost the
output to 25 Watts (pep).
The Pico-Macom model MPCD demodualator is a frequency agile, NTSC analog TV receiver covering
all standard broadcast and cable TV channels. This includes cable TV channels 57-61 which fall in the
amateur 70 cm band. We used it on Ch 60 (439.25 MHz).
These are in the CATV industry standard "Mini-Mod" package. They both require +12Vdc & +5Vdc
for power. A/V outputs and inputs are composite video and line level, mono audio.
TV Rptrs Rptr-133.doc ( 6/10/23, kh6htv) p. 11 of 11
Both items have been discontinued by Pico-Macom. New demodulator units can sometimes still be
found on the internet but now at very high prices in the $350 range. ATV Research is selling new the
Holland HMMS, single channel modulator, similar to the MPCM45 for $148. We are willing to sell
the pair for $130 which includes free shipping via USPS priority mail. Interested ? -- contact Jim,
KH6HTV via email ... tr-133.pdf
Prispevkov: 1012
Pridružen: 28 Okt 2004, 21:07

Re: revija ATV

OdgovorNapisal/-a s58ru » 30 Jun 2023, 21:52

TV Rptrs Rptr-134.doc ( 6/30/23, kh6htv) p. 1 of 14
Boulder Amateur
Television Club
TV Repeater's
July, 2023
issue #134
BATVC web site:
ATN web site:
Jim Andrews, KH6HTV, editor -
As hopefully everyone is aware major changes to amateur access to the 23cms band are set to be agreed
at WRC-23 in October. Barry, G4SJH, is leading the IARU negotiation team and gave an update at the
TV Rptrs Rptr-134.doc ( 6/30/23, kh6htv) p. 2 of 14
RAL microwave roundtable on Sunday June 18th. For the full background to the changes watch the
video of Barry’s presentation at the Martlesham microwave roundtable.
The changes are significant and there will be a stringent power limit (less than 1 watt) to the majority
of the band apart from 4 segments seen below. Negotiations are still ongoing and nothing will be
decided until after the WRC. --– It is hoped there will be a segment centered around 1256 MHz to
accommodate digital repeater inputs and simplex operation.
It is important that everyone prepares for these changes so they do not come as a surprise when Ofcom
updates your license - we will try post the latest updates on the BATC forum here: ... 718#p33718
Whatever agreement is made, FM ATV operation will no longer be possible below 1300 MHz and it is
likely the IARU and BATC contest rules will be amended before the end of 2023 to exclude FM entries
on 23 cms.
Reprinted from the latest Summer, 2023 issue of the BATC's CQ-TV magazine. issue #280, page 9
Once again the Boulder Amateur Radio Club (BARC) set up their field day operation on Boulder
County mountain parks open space, Betasso Reserve. A prime mountain top setting. Normally no
overnight stays are allowed. But each year BARC gets special permission from the county to use the
picnic shelter house and stay overnight for the weekend. Allen, K0ARK, once again brought his
complete portable HF station. The key element in Allen's station is his trailer mounted, electrically
driven crank-up tower and a Step-IR tunable yagi beam antenna on a rotator. It is used for BARC's
SSB station. The BARC CW station this year used a horizontal wire, delta loop antenna fed with
ladder line. The above photo on the left shows the Step-IR antenna, the CW (white) and SSB (yellow)
tents. Plus in the foreground was a BARC member getting ready to use the air gun to shoot a tennis
TV Rptrs Rptr-134.doc ( 6/30/23, kh6htv) p. 3 of 14
ball with a pull line over a tree to then be used to pull up a leg of the delta loop. The photo on the
right shows the SSB station rapidly logging lots of 20 meter contacts. The mountain top location and
Step-IR antenna configuration put out such a strong signal that W0DK was able to command their own
frequency, call CQ Field Day and just sit back and let the "hunt-n-pouncers" find and call us. This was
the first year that BATVC, ATVers did not participate with any ATV demo at the BARC field day
DVB-T RFI Experiment
Jim Andrews, KH6HTV
Many years ago (2014), when we first started working with digital ATV, I made experiments to
determine the RFI susceptibility of DVB-T receivers. At the time, the concern was for the Boulder
ARES (BCARES) operations running four simultaneous, 70 cm, ATV transmitters covering the
University of Colorado football games for the CU police dept. Could we run then several DVB-T
transmitters on adjacent channels, and / or a mix of analog and digital TV transmitters. I also included
a few tests using CW interfering signals. The results were documented in my application note, AN-19,
entitled "Analog & Digital TV Co-Channel & Adjacent Channel RFI Measurements". ( available at )
With our current issues of a whole lot of RFI on our 70 cm input to our Boulder W0BTV, DATV
repeater, I decided to once again perform some measurements on the susceptibility of a DVB-T
receiver to an interferring CW signal.
The above block diagram shows the test set I assembled to perform the tests. The tests were run
using a DVB-T test signal on 441 MHz with a band-width of 6 MHz. The various digital signal
parameters are shown on the block diagram. The RFI source was an HP-8640B signal generator
producing an unmodulated CW sine wave of known frequency and level. The DVB-T and CW signals
were added together in a passive, 3 dB Wilkerson power divider/combiner. "Live" video with lots of
TV Rptrs Rptr-134.doc ( 6/30/23, kh6htv) p. 4 of 14
motion and audio was provided by a DVD player. Having continual motion in the video is important
to be able to detect when freeze framing occurs indicating RFI interference. The Red/Green signal
status LED on the Hi-Des receiver is also a great indicator of when RFI occurs. If it is flickering
red/green or turns red, the DVB-T signal is being interfered with.
The first test was to determine the digital threshold sensitivity of the HV-110 receiver. This was the
minimum signal level at which solid video and audio was obtained with no freeze framing. Also the
red/green LED glowed a solid green. The receiver sensitivity was found to be -92 dBm. At this
level, the on screen display showed a signal/noise ratio of 8 to 9 dB.
CW RFI tests were then run with the DVB-T test signal into the receiver being set to +3 dB and also
+10 dB above digital threshold. i.e. -89 dBm and -82 dBm. At these levels the S/N read 11 dB and
18 dB respectively. I performed the tests over a range of ±8 MHz from the center frequency. i.e.
from 433 MHz to 449 MHz in 1 MHz increments, except at the channel band-edges. In each case, I
started with a very low level CW RFI signal of -130 dBm. I brought it up in 10 dB steps until I got
freeze framing. I then backed off the signal by -10 or -20 dB and using the vernier amplitude control
slowly increased the signal level until I reached the threshold of freeze framing. It was also indicated
by flickering of the HV-110's red/green LED. Then backed off to again have solid video. I then
recorded the signal generator setting. Corrected it for the additional 20 dB loss in the test set and
calculated the difference between the interfering RFI signal and the average power of the DVB-T
RESULTS: So what were my findings? I found that a single interfering CW signal anywhere
within the 6 MHz channel ( i.e. from 438 to 444 MHz ) needed to be about +23 to +30dB stronger than
the average power of the DVB-T signal to cause interference. On the band edges, ±500 kHz beyond
the channel edges ( i.e. 437.5 & 444.5 MHz), there was starting to be additional rejection. The RFI
signal needed to be about +35 dB stronger. Beyond ±1 MHz from the channel edges, the RFI
rejection was considerably better. RFI signals there needed to be 40 to 60dB stronger than the DVB-T
signal. I obtained similar results from both tests at +3 dB and +10 dB above digital threshold.
I also noticed some variablity in my measurements. Not always repeatable. Also, the receiver at
times seemed to be able to correct and eliminate the RFI. I sometimes observed it initally being
momentarily having a freeze frame for a second or two, but then correcting for it and then allowing me
to increase further the RFI signal level without freeze framing.
W0BTV, 70 cm, 2 MHz BW
Experiment - a Bust
Recently, we modified the Boulder, Colorado ATV repeater by removing the unused 439.25 MHz,
analog TV receiver and replacing it with a 439 MHz, 2 MHz BW, DVB-T receiver. The hope was to
TV Rptrs Rptr-134.doc ( 6/30/23, kh6htv) p. 5 of 14
be able to minimize the RFI which was clobbering all but the strongest of our 70 cm, 441 MHz, 6
MHz BW, DATV signals. Nope -- didn't make any appreciable improvement. Warning, the
following is a tale of disappointments.
What we found was that we got similar results with both the 441/6 MHz receiver and 439/2 MHz
receiver. Our measurements, using the repeater's on-screen-displays of signal strength and s/n showed
that we needed very strong signals to overcome the unknown RFI. If the input DVB-T signal dropped
down to -60dBm or weaker, it started being clobbered with freeze frames from the RFI.
So, after the fact, we then did some spectrum studies to see what is happening at our repeater site. We
don't have ready 24/7 access to the government building where our W0BTV-DATV repeater is located.
We have to schedule a visit appointment several days in advance to gain access to the radio room or the
roof top. The building itself sits way above the city of Boulder, by 800-900 feet, on a mesa, nestled up
against the front range of the Rocky mountains. So we did our measurements sitting in our car in the
parking lot. The repeater's antennas are another 120 feet above the parking lot. From either location,
we see a really long way to Denver and out onto the eastern Colorado prarie. At the repeater's
location, it is exposed to all the RF signals coming out of Denver and all of north-eastern Colorado.
We used the new, really low cost, TinySA-Ultra spectrum analyzer. The mobile antenna used was a
Diamond NR2000NA (2m/70cm/23cm). We tried lots of different settings and looked at various
portions of the ham 70cm band, plus above into the business band. The band below 445 MHz was
fairly quiet. We did see the occasional ham FM voice signal pop up now and then. We also noted
activity around 434 MHz. Above 445 MHz, it was a totally different story. Lots of signals in the
445-450 region which for the most part were FM voice repeater outputs. Then above 450 MHz, in the
business band, it was painted almost wall-to-wall with signals. Careful monitoring however showed
that the most likely culprit was perhaps a signal at 445.050 MHz. So punching that frequency into an
HT and listening to it, we found it was not voice, but was intermittant bursts of data. There were also
very strong FM voice repeater signals in the 447 MHz area.
So back to the drawing board. Our repeater configuration was set with a 70 cm, ATV channel filter
tuned to a center frequency of 441 MHz with a -3dB band-width of 6.3 MHz. Our next step was to try
QSYing down a few MHz. Don, N0YE, had another home-brew, ATV channel filter so he retuned it
for a center frequency of 439 MHz. The hope was to put more of the BPF skirts onto the signals at
445 and above.
OK, back to the repeater site on Wed, June 21st. Don swapped out the 441 for the 439 MHz ATV
channel filter. In the meantime, Jim retuned the Hi-Des HV-120 receiver from 441 down to 439.
While we were at the repeater site and had the repeater's receive antenna disconnected from the
repeater, we had it attached to a TinySA-Ultra spectrum analyzer. We wanted to see what signals were
actually being picked up for it. The below plot is what we saw. The green trace was the peak signals
recorded over the 25 minute time interval we were in the radio room. We didn't see anything
significantly different from earlier observations in the parking lot.
Now, back home that evening, Don was able to run some controlled experiments at 439/6 MHz from
his home QTH. He put a step attenutuator between his Hi-Des modulator and the rf power amplifier.
TV Rptrs Rptr-134.doc ( 6/30/23, kh6htv) p. 6 of 14
He was also able to monitor the repeater's output and note the repeater receiver's on-screen S meter &
s/n meter displays. He was able to drop his signal strength down to as low as -85dBm into the
repeater before seeing any freeze framing. It appeared we had solved the problem.
Wrong ! The next morning Jim tried the same experiment, but was unsuccessful. There were times
when the s/n hit max. of 23dB, but then would be clobbered again by something causing the repeated
pictures to freeze up. On our Thursday, June 22ed, afternoon weekly net, we had a brief period for
about 5 minutes before the net when Don's 439/6 MHz signal came through great. But then once the
net started, everyone trying out 439/6 was clobbered with lots of freeze framing, even when running
high power.
We returned to the NCAR parking lot again on other days with both the spectrum analyzer and also a
DVB-T receiver to simultaneously video monitor the repeater's output signal and look for any strong
RFI signal(s) we could correlate with the freeze framing we were observing. No luck.
Bottom Line for us is at present --- our cross-band repeater configuration of 23 cm input and 70 cm
output works best. Where do we go from here ? Big Question ? ? ? Do we just kiss off 70cm as an
input ? ? ? Jim is voting to say "I have had it and want to just go back to 441/6 MHz and rip out the
439/2 MHz receiver." But Don is saying "No way, I want to continue experimenting and hopefully
find a solution." Guess Don wins for the present. So we will make some more hardware adjustments
at least. 73 de Don, N0YE, & Jim, KH6HTV, trustees
70 cm RFI at the W0BTV repeater site
TV Rptrs Rptr-134.doc ( 6/30/23, kh6htv) p. 7 of 14
We used the W0BTV's Diamond X-6000 receive antenna. Sweep 430 MHz to 460 MHz, 5 MHz/div.
Vertical: 10dB/div. Top level = -10dBm. Resolution band-width set to 30 kHz. Yellow trace is single
"live" sweep. Green trace was in peak hold mode for 25 minutes. Bottom 1/2 with blue background
was waterfall display of green trace.
5 cm FM-TV Transmitters -- How
do they compare ?
Noel, G8GTZ, of BATC demoing new IC-905 in You-Tube video
ICOM IC-905: With the recent introduction of the new ICOM IC-905 Microwave Transceiver,
we hear that it includes FM-TV capability. Will it be compatible with other existing amateur FM-TV
gear ?
In our May issue #130, we said that Mike, WA6SVT, and Gary, W6KVC, had recently tested a new IC-
905 and posted their tests on YouTube. ( ) Their
1/2 hour video included comments about testing the FM-TV performance. They reported (1) the video
modulation level was a bit low, (2) the HF video response rolled off a bit and (3) the sound sub-carrier
frequency was not adjustable. As a result, it was not on what ATN-CA uses. But it did work for ATV.
Dave, G8GKO, of the BATC in the U.K. has informed us that he is working presently on an evaluation
of the IC-905. It will be published by RadCom. He then plans to publish the results he finds for ATV
in the BATC's CQ-TV magazine. We will be anxiously awaiting to read those articles of Dave's.
There is another NEW (as of May 30th) You-Tube video evaluating the IC-905. This 18 minute video
devotes 1/2 of it to a field test demo of the ATV capability of the 905. The video was put together by
TV Rptrs Rptr-134.doc ( 6/30/23, kh6htv) p. 8 of 14
BATC members, Dave Crump, G8GKO and Noel Matthews, G8GTZ, along with Bob McCreadie,
G0FGX. They include a live demo of a 5.8 GHz, FM-TV QSO using a pair of IC-905s. Noel makes
the statement in the You-Tube video that the video standard used by the 905 is compatible with the
video system used for 5.8 GHz drones. The URL link is:
DRONE 5.8GHz FM-TV: I have been pushing ATV
folks to continue using analog ATV, especially on the 5cm ( 5.8
GHz) band using the extremely low cost ( $30 ) drone video kit
from Amazon of a complete FM-TV transmitter and receiver. I
have written about it in several previous newsletters. We ATV
hams here in Boulder, Colorado have also done some DXpeditions
with them and gotten some really long distances for ATV
contacts. In addition, we added one of the transmitters to our
W0BTV, ATV repeater to serve as a 5 cm, FM-TV Beacon running
So, all this new excited talk about the IC-905 got me to wondering,
just what were some of the performance specs. of the Amazon 5.8
GHz, drone FM-TV gear. The gear has no manufacturer's name
on it. Just model numbers. They are TS832 for the transmitter.
RC832 for the receiver. Their instruction manuals tell us very
little. The only relevant specs. for the TS832 are the channel
frequencies ( 40 channels from 5645 to 5945 MHz), modulation type of wideband FM, output power
of 600mW, Sound Sub-Carrier frequency of 6.5 MHz, Video format NTSC/PAL, Video input of 1
Vptp into 75 Ω, video bandwidth of 8 MHz, audio input of 1 Vptp into 10 KΩ, 12Vdc @220mA.
Key relevant specs. missing are: What is the Deviation ? Does it use Pre-Emphasis / De-Emphasis ?
and if so, to what spec. ? We here in Boulder have used the gear successfully, but without inquiring
about these parameters. Guess we weren't bothered at the time as there was nothing else to compare it
with and try to operate interchangablity with. Now with the new IC-905 coming on the market, we do
need to be concerned.
So, I decided to at least try to answer some of our questions. I lashed together a test setup to measure
the video deviation. I used the system documented in my application note, AN-14 "FM Transmitter
Deviation Adjustment & Calibration". The easiest technique to measure deviation is the Bessel
method shown there. It consists of putting a 1 Vptp sine wave into the video transmitter and looking
at it's rf spectrum. The spectrum consists of a large number of sidebands of diminishing amplitude.
Of particular interest is to watch the zero carrrier frequency. Slowly bring up the frequency and watch
for when the carrier is nulled out for the first Bessel function null. Equation (1) is the modulation
index χ = D / m where D is the deviation and m is the modulation frequency. The first Bessel null
occurs when χ = 2.405.
TV Rptrs Rptr-134.doc ( 6/30/23, kh6htv) p. 9 of 14
This spectrum analyzer screen grab photo shows the results of the deviation measurement. The span
is 20 MHz. The scales are: 10dB/div & 2 MHz/div. The magenta trace is the spectrum with no video
modulation applied. All we see is the carrier at 5.905 GHz and the upper and lower sound sub-carriers
± 6.5 MHz on either side of the carrier. The yellow trace is now with a 1 Vptp sine wave into the
video input connector. The frequency of this modulating sine was adjusted to find the first null in the
Bessel function. It was measured to be m = 1.086 MHz. Thus putting this value in the above
equation, I found the deviation of this FM-TV transmitter to be 2.6 MHz. Not 4 MHz as in commonly
used for ATV. However, I did make the assumption that pre-emphasis was not being used in the
transmitter. I am unsure how to verify this.
Deviation Measurement
This plot shows a typical spectrum obtained
from this same drone transmitter, but the
input video signal was typical "live" video
obtained from a DVD player playing a
movie file. The span is now 50 MHz ( 5
MHz/div & 10 dB/div), 30 kHz BW.
Yellow trace is capture of a single sweep.
Magenta trace was peak hold mode for 3
minutes of video.
"Live" Video Spectrum
TV Rptrs Rptr-134.doc ( 6/30/23, kh6htv) p. 10 of 14
The next test I performed was to check the overall video frequency response of a drone transmitter /
receiver pair. The transmitter was the TS-832. The companion receiver was the model RC-832. I
attenuated the 600mW output of the transmitter with 90dB of SMA attenuators before inserting the
signal into the receiver. I input a test sine wave of 200 mV (ptp) into the 75Ω input of the transmitter.
Looking at the receiver output on a Siglent digital oscilloscope, terminated in 75Ω, the output signal
was also 200 mV (ptp). Thus 0 dB insertion gain for the combo. I then put the RC-832 video output
into a Rigol spectrum analyzer. I measured the swept frequency video response. I found it was flat
from 100 Hz up to 1 MHz. It then peaked a bit rising 1 dB at 1.5 MHz and flattening out at +2dB from
2.3 to 5.0 MHz. It then rolled off to help eliminate feed-thru of the 6.5 MHz sound sub-carrier (SSC).
It was -3dB down at 5.7 MHz, -10dB at 6.1 MHz and -20dB at 6.3 MHz.
Conclusion ? -- Well, if your only objective is to do microwave FM-TV on the 5cm band, then there is
a very significant 20dB $$ advantage to sticking with the drone gear (i.e. $30 vs. $3,000 for the IC-
905). Essentially identical performance, both from an rf and video perspective.
73 de Jim, KH6HTV, Boulder, Colorado
FAA, 23 cm RADAR Spectrum
What does our Denver, 23 cm, FAA radar look like on a spectrum analyzer ? Recently, I connected my
23 cm, loop yagi antenna to my Rigol spectrum analyzer and tuned to 1265 MHz. This is what I saw.
The resolution bandwidth was set to the widest possible of 1 MHz. The center frequency was 1265
MHz with a 20 MHz span. The yellow trace is a "live" single sweep. The magenta trace was set to
peak hold. It took several minutes to build up the magenta trace. The FAA radar is located in Parker,
Colorado, about 35 air miles from our W0BTV repeater site. My home antenna was pointed due west
TV Rptrs Rptr-134.doc ( 6/30/23, kh6htv) p. 11 of 14
at our repeater site, about 12 air miles away. The radar was on the side of my beam. What I was
really looking at was the reflection of the radar pulses from the Flatiron mountain directly to the west
and behind our repeater. As the radar dish rotated, I could see the intensity of the radar pulses go
dramatically up and down. Ony the highest peaks were captured on the magenta trace. I measured
as a weak reflection a strong -50dBm signal. One can only imagine how strong the radar must be at
our TV repeater and why it was clobbering our 23 cm receiver before Dan, K0DGS, designed for us a
great band-pass, band-notch filter. It is a direct line-of-sight path from our repeater to the Parker
As a side note -- I also tried the same experiment using my new TinySA-Ultra spectrum analyzer. I
used the same settings as my Rigol. It was worthless for measuring the radar signal. It gave almost
no indication of the presence of the radar signal.
73 de Jim, KH6HTV, Boulder, Colorado
Another Mid-West Band Opening
Saturday, 3 June, 7am
This is an an A5 signal from Charles Beaner in
Morrow County, Ohio passing through the
W8BI repeater in Dayton, Ohio on its DVB-T
output…at 85 miles…
photos tnx to Dave, AH2AR
Hi Jim --- Just wanted to mention that you got it a little
wrong, do appreciate you running the photo of the incoming
ATV DX signal from WB8LGA through the repeater, but you
might want to ask when you add information to the photos I
send you. The OSD information displayed on the monitor is
NOT the OSD that the ATV repeater is receiving. Those OSD
values are from the receiver at my home QTH from the
incoming DVB-T signal from the W8BI repeater. The repeater
will only display the OSD if the HV110 at the repeater site is
receiving a digital signal. As the signal that the ATV repeater
was receiving was an A5 signal, the repeater will not be
retransmitting the OSD display. Confusing, ain’t it!!! It was
quite remarkable that the ATV repeater was receiving Charles’
A5 video P5…. Closed-circuit, rare to experience that kind of
analog video from 80+ miles distance…
Cheers, Dave P. , AH2AR, DARA, Dayton, Ohio
p.s. Here is another photo from Dayton Hamvention. It shows
a group of hams checking out some of the ATV gear on display
at the ATN booth.
TV Rptrs Rptr-134.doc ( 6/30/23, kh6htv) p. 12 of 14
YouTube links to N8ZM "RF Lab" Noise
figure and Gain on 70 cm preamps
AirSpy 70cm Preamp (unmodified, 434 MHz filter in-place), $11 Amazon Commercial off-air TV
AirSpy Modified 70cm Preamp (434 filter removed):
VHF Designs Ukranian 70cm LNA preamp:
Jim Andrews', KH6HTV, model 70-LNA, 70cm Preamp:
Thanks to Dave, AH2AR, for sharing these with us.
SatLink Issues: Fran, PAFEX, in Holland writes ---- "Hello Jim. Thanks for your
I’ve read that you have tested the Satlink WS-6990 modulator. I’ve just received that same Satlink and
I’m trying to get it work with HDMI input, also tried CVBS and that gives me a picture on my Satlink
satfinder dvb-t/s/c but no picture from HDMI. Do you know if the modulator is critical at setup??
I have set it at 430 Mhz both modulator and satfinder at dvb-t and on the screen I can read the same
value’s for PID….as set on the modulator, so I think it’s getting the correct info but no picture."
Editor's Comment: We too encountered the same problem with our WS-6990. Could only get it to
work with analog composite video input, but even then the analog audio didn't work. Now glad to
hear our's was not a unique problem. Fran is seeing the same issue. Thus it must be a built-in defect
in the SatLink box. We had written about the WS-6990 a year ago. Now wish we hadn't. Our
conclusion now is it is a piece of JUNK ! Do Not Buy ! It is too bad, as we all were really wishing
we could find a low cost supplier for DVB-T modulators.
Perhaps others have gotten them to work? If so, then please share with our readers your experience
and solution.
TV Rptrs Rptr-134.doc ( 6/30/23, kh6htv) p. 13 of 14
ARES & ATV: Hi Jim --- Always a great newsletter. Thanks for keeping me in the loop. I
thought I wouldn't be "involved" with any ARRL type duties when I moved here but I was "enlisted" by
the New England Division Director whom I believe you know, Fred Kemmerer, AB1OC. (also an
ATVer) Because of my past experiences with ARES in Colorado, I am now an Assistant Director for the
New England Division, responsible for emcomm communications! Yikes! What did I sign up for?...
Handling a one-state ARES group is one thing but now being responsible for the six states ARES
groups plus the Hudson Valley of NY state is certainly a whole different world. Fortunately, there are a
some really good SECs and SMs but there is missing the situational awareness aspect of any
emergency as we were so good at with BCARES and ATV.
73 de Jack Ciaciaa, WM0G, Nashua, New Hampshire
Editor's Note: Jack formerly lived in Boulder, Colorado for many years. He was extremely active in
ham radio here. He is an avid HF DXer. Over the years he had served as the president of our ham
club, the chairman (EC) of our local ARES group, a SWAT team volunteer (for ATV video), and more
recently the ARRL section manager for Colorado. In 2020, Jack and his wife Mary retired and moved
back to his original home area of New England.
W0BTV Details: Inputs: 23 cm Primary (CCARC co-ordinated) + 70 cm secondary
all digital using European Broadcast TV standard, DVB-T 1243 MHz/6 MHz BW (primary),
plus 441 MHz/6 MHz BW and 439 MHz/2 MHz BW
Outputs: 70 cm Primary (CCARC co-ordinated), Channel 57 -- 423 MHz/6 MHz BW, DVB-T
Also, secondary analog, NTSC, FM-TV output on 5.905 GHz (24/7 microwave beacon).
Operational details in AN-51c Technical details in AN-53c. Available at:
W0BTV ATV Net: We hold a social ATV net on Thursday afternoon at 3 pm local
Mountain time (22:00 UTC). The net typically runs for 1 to 1 1/2 hours. A DVD ham travelogue is
usually played for about one hour before and 1/2 hour after the formal net. ATV nets are streamed live
using the British Amateur TV Club's server, via: Select ab0my or n0ye. We
use the Boulder ARES (BCARES) 2 meter FM voice repeater for intercom. 146.760 MHz ( -600 kHz,
100 Hz PL tone required to access).
Newsletter Details: This is a free newsletter distributed electronically via e-mail to
ATV hams. The distribution list has now grown to over 500+. News and articles from other ATV
groups are welcomed. Permission is granted to re-distribute it and also to re-print articles, as long as
you acknowledge the source. All past issues are archived at:
TV Rptrs Rptr-134.doc ( 6/30/23, kh6htv) p. 14 of 14
Free advertising space is offered here to ATV hams, ham clubs
or ARES groups. List here amateur radio & TV gear For Sale -
or - Want to Buy.
No, I am not selling this old TV receiver.
I recently saw it while shopping in the
Longmont, Colorado Flea Market &
Antique Store. The sign says it is a 1949
Motorola TV receiver. Asking price was
$150. ... tr-134.pdf
Prispevkov: 1012
Pridružen: 28 Okt 2004, 21:07

Re: revija ATV

OdgovorNapisal/-a s58ru » 07 Jul 2023, 15:10

TV Rptrs Rptr-135.doc ( 7/6/23, kh6htv) p. 1 of 11
Boulder Amateur
Television Club
TV Repeater's
July, 2023
2ed edition, issue #135
BATVC web site:
ATN web site:
Jim Andrews, KH6HTV, editor -
Kids Have Successful BALLOON
Flight with DATV Video
Breaking NEWS Bulletin -- We just received this exciting email from Drew, AC3DS, in
Fairview, PA, in north-west Pennsylvania near Lake Erie. -------- "Jim, We successfully launched our
High Altitude Balloon and had live video for the entire duration except the last 2 minutes before
TV Rptrs Rptr-135.doc ( 7/6/23, kh6htv) p. 2 of 11
touchdown. It reached a little over 90,000 feet. If you would like to see the video, here is a link to our
livestream of the event: 73 de Drew, AC3DS"
This was a STEM project of the Harbor Creek School District. The 4 1/2 hour You Tube video
documents their June 29th balloon flight from start to recovery. It definitely shows the enthusium
exhibited by all the kids involved. The actual flight lasted a little over 2 hours.
Drew, AC3DS, designed the DVB-T system. Rick, WA3MKT, designed the balloon's ATV antenna.
The ATV transmitter consisted of a Raspberry Pi camera with HDMI output, a Hi-Des model HV-320
modulator and a KH6HTV Video model 70-7B rf linear power amplifier. The amplifier's output power
was throttled back below it's normal 3 Watts to conserve battery power. Eight other hams also
assisted with the project.
Count Down 5, 4, 3, 2, 1 - Launch !
Mission Control Center First Video Views from the balloon
View from Space ! Descent -- On our way down !
TV Rptrs Rptr-135.doc ( 7/6/23, kh6htv) p. 3 of 11
Now to find the downed balloon We found it !
DATV Repeater Progress
We have recently had some correspondence with John, K0ZAK, about his efforts to get the Baltimore,
Maryland, ATV repeater up and running with digital TV. I am including here some of his recent email
6/25 --- Hi Jim. I've been tasked with rebuilding the second Baltimore ATV repeater. The BRATS
club was in the process of upgrading it to Digital before Covid hit and the hospital it is located in got
locked down. The upgrade has been stalled for various reasons since then.
I just went there and retrieved the equipment to finish the upgrade. The transmitter is a HiDes HV-100
driving one of your 10 watt, model 70-9B amplifiers.
The club never got around to putting a digital receiver on line. There is still an analog receiver at the
location. I was planning on replacing it with a HiDes HV-110 but am now a bit concerned after reading
your problems with the HDMI cables and HDCP encoding in one of your recent newsletters. I'm
hoping that I don't run into that issue.
I have built a BATC, ATV controller based on a RPI4 for the repeater site, which will be driving a
HDMI seamless switcher. I have been reading about using certain HDMI splitters to get around the
HDCP issues, but I believe you mentioned that didn't work for you. I have noted that the AVsender
program allows you to turn off HDCP on the HV100& HV320 transmitters, but see no equivalent way
to do that on the HV110 receivers. That make sense however as you have the choice or usingit or not
TV Rptrs Rptr-135.doc ( 7/6/23, kh6htv) p. 4 of 11
on transmitting your own video, but not receiving someone elses. I may just have to locate an older
HV110 like you did.
John Kozak, K0ZAK
6-26 -- Due to the lack of info available for the current controller and hardware, and changes in the
TMARC frequency coordination for the repeater, we thought it best to start with a clean sheet on the
repeater re-design, using what parts that may be available.
Plans are to have the transmitter on 427.25 using the HV-100 & your 70-9B amplifier running DVB-T
at 2 MHz bandwidth. The Controller will be the BATC repeater controller built on a Raspberry Pi 4
driving an HDMI seamless switcher. Receiver for now is planned to be a HiDes HV-110 set to 439.25
Mhz DVB-T @ 2 MHz bandwidth. Analog receivers and alternate bands will be considered in future
upgrades. All equipment will be supported with PC's connected via a network to allow remote
reprogramming and resetting as needed. Dead Man resetting will be built into the system in case of
unexpected lockouts. The BATC controller will also allow DTMF control over FM radios.
Alternate receive plans are to install my BATC Knucker and Minituner receivers into the system so as
to allow realtime comparisons of DVB-T & DVB-S inputs using different bandwidths. These receivers
however are not really repeater friendly. They will require manual resetting every time the power
drops. They will really just be used for testing alternate transmission modes.
I have been waiting for Art Townslee's latest Versatuner receiver hoping it would be better suited for
this task, but from what he said in his recent Dayton hamfest talk, the DVB-T & DVB-S frequency
ranges don't overlap. Therefore I won't be able to do direct mode comparisons on 439.25 MHz
Thanks for all your comments and support for this ATV stuff,
John Kozak, K0ZAK
Editor's Comments: I am sorry to say that I can no
longer endorse the Hi-Des DVB-T receivers. I have had way
too much grief in the past year with their new production
receivers. They are too finicky about their HDMI
connections. My current HV-110 for example will only work
with my 24" Visio TV receiver/monitor. It refuses to display
anything on two other video monitors, I have here in the
shack. Both are capable of 1080P resolution with screen
sizes of 7" and 11" and operate from 12 Vdc power. They
were purchased for out in the field, portable or mobile ATV
However, for narrow bandwidths of less than 6 MHz, our choices for a DVB-T receiver are extremely
limited. Currently, for hams wanting to do DVB-T, ATV on the 70cm band, using 6 MHz band-width,
I recommend using the "Combo" DVB-S / DVB-T receiver shown here. Most all of the Boulder ATV
hams are using them and are quite happy with their performance and lack of issues. For more details,
see my app. note, AN-65 ---- Jim, KH6HTV
TV Rptrs Rptr-135.doc ( 7/6/23, kh6htv) p. 5 of 11
ATN - Southern California
2 MHz BW, DVB-T Modulator Settings
Roland, KC6JPG, has provided us with a screen grab shot showing us his recommended settings for
DVB-T modulation with 2 MHz band-width. In quick summary, the major settings are: Media Config
TV Rptrs Rptr-135.doc ( 7/6/23, kh6htv) p. 6 of 11
= HDMI, MPEG2 video encoding, 720P resolution, 2.6 Mbps max. bit rate. MPEG2 audio encoding at
128 Kbps. Trans Config = 16QAM, 8K FFT, 3/4 Code Rate and 1/16 Guard Interval. For PID, they
use: PMT = 640, Video = 641 & Audio = 642
DVB-T Signals
Jim Andrews, KH6HTV
I consider this book to be the "Bible" for most all
questions relating to digital TV.
The author, Walter Fischer, Dipl. Ing. was a
Television engineer working in the Broadcast
division for Rohde & Schwarz, in Munchen,
The book is over 800 pages in length. It starts out with analog TV. Then moves on to MPEG, both
audio and video. It discusses the various TV systems of DVB-C, DVB-S, DVB-T, ISDB-T & ATSC
plus IPTV. Also included are digital audio of DRM and DAB.
It has a whole chapter devoded to "Measuring DVB-T Signals". Chapter 21, pages 421-450. A key
parameter many of us use when setting up the drive level for our RF power amplifiers is the
measurement of the RF output power and also the out-of-channel, spurious spectrum, shoulder
attenuation. I would like to address these here in this newsletter. They all use a spectrum analyzer
for the measurements. Reproduced here directly from section 21.2, pages 425-426 is as follows:
21.2 Measuring DVB-T Signals Using a
Spectrum Analyzer
"A spectrum analyzer is very useful for measuring
the power of the DVB-T channel, at least at the
DVB-T transmitter output. Naturally, one could
simply use a thermal power meter for this purpose
but, in principle, it is also possible to use a
spectrum analyzer which will provide a good
estimate of the carrier/noise ratio. Firstly, however,
the power of the DVB-T signal will now be
determined. A COFDM signal looks like noise and
has a crest factor which is rather high. Due to its
similarity with white Gaussian noise, its power is
measured in a comparable way.
TV Rptrs Rptr-135.doc ( 7/6/23, kh6htv) p. 7 of 11
To determine the carrier power, the spectrum analyzer is set as follows: On the analyzer, a resolution
bandwidth of 30 kHz and a video bandwidth of 3 to 10 times the resolution bandwidth, i.e. 300 kHz, is
selected. To achieve a certain amount of averaging, a slow sweep time of 2000 ms is set. These
parameters are needed because we are using the RMS detector of the spectrum analyzer. The following
settings are then used:
• Center frequency: center of the DVB-T channel
• Span: 20 MHz
• Resolution bandwidth: 30 kHz
• Video bandwidth: 300 kHz (due to RMS detector and logarithmic scale)
• Detector: RMS
• Sweep: slow (2000 ms)
• Noise marker: channel center (resultant C’ value in dBm/Hz)
(editor's note: I also recommend using the signal averager with at least 10 averages)
To measure the power, the noise marker is used because of the noise-like signal. The noise marker is
set to band center for this but the prerequisite is a flat channel which can always be assumed to exist at
the transmitter. If the channel is not flat, other suitable measuring functions must be used for
measuring channel power but these depend on the spectrum analyzer.
The level indicated in the useful band of the DVB-T spectrum (Fig. 21.5.) depends on the choice of
resolution bandwidth (RBW) of the spectrum analyzer (e.g. 1, 4, 10, 20, 30 kHz, etc.) with respect to
the bandwidth of the DVB-T signal. The signal bandwidth of the DVB-T signal is
• 7.61 MHz in the 8 MHz channel,
• 6.66 MHz in the 7 MHz channel,
• 5.71 MHz in the 6 MHz channel."
(editor's note: This is due to the presence of a very sharp roll-off of the DVB signal just inside the
band edges to provide guard bands. Thus a 6 MHz signal does not really fully occupy a full 6 MHz TV
channel. )
Editor's Comments: A spectrum analyzer's markers can thus be used to measure the actual rf power
in a DVB-T signal, but a dB correction factor must always be used to account for the difference
between the resolution bandwidth and the signal bandwidth. For example on my Rigol DSA-815
spectrum analyzer I have found that I need to use a dB correction factor.
I used a Hi-Des HV-320E modulator as my signal source on the 70cm band. I first measured the true
average power of a 6 MHz BW, DVB-T signal using an HP thermistor power sensor with my HP-432
power meter. I set the rf power to approximately 0 dBm. I then measured the same signal on the
Rigol. The spectrum from the HV-320 is not perfectly flat, but has about a 1dB ripple across the pass
band. Thus there is some uncertainty in where to exactly set the SA's marker. Thus expect a similar
amount of uncertainty in the absolute accuracy of your power measurement.
You can use either the marker readout in Power (dBm) or the Noise marker readout in dBm/Hz. Using
30 kHz resolution bandwidth and 300 kHz video bandwidth, with the power marker, I got about -22 to -
23 dBm. Thus a correction of +22/23dB needs to be added to the readings to determine the actual rf
power of a 6 MHz BW, DVB-T signal. If I used the Noise Power marker, then the value was about -
TV Rptrs Rptr-135.doc ( 7/6/23, kh6htv) p. 8 of 11
67 dBm/Hz. The correction factor to account for the total bandwidth of a 6 MHz channel (actually
5.71 MHz) correcting 5,710,000 Hz relative to 1 Hz is to add 10*log(5,710,000) = +67.7 dB to the
Noise Power marker readings.
If I changed the resolution bandwidth on the Rigol SA to it's various settings of 1 MHz, 300 kHz, 100
kHz, 30 kHz, 10 kHz, 3 kHz, etc. -- I found there was essentially a 5 dB change in the Power marker
readings between each band-width. Thus going from 30 kHz to 100 kHz, the reading increased from -
23 dBm to -18 dBm. No change occured in the Noise Power marker readings as they were always
expressed as dBm per Hz.
When setting up your spectrum analyzer to make measurements on a DTV signal, keep in mind that the
waveform is definitely not a sine wave, but looks more like totally random noise with lots of peaks and
valleys. For accurate measurments, the peaks must not exceed the linear upper limit on your analyzer
or severe compression will occur. Always best to start with too much attenuation and then remove
some to optimize the results. For example the crest factor for DVB-T is theoretically 40 dB higher
than the average power. For typical transmitters it is usually limited to about 13 dB or a bit less.
Tiny-SA - Ultra Spectrum Analyzer:
So, can I also use the low cost, Tiny SA ? The
answer is a definite YES ! I found that it works
quite well for making measurements on DVB-T
signals. I got essentially the same results as I did
with my more expensive Rigol. Using the same
identical settings as recommended by Fischer and
used on the Rigol, I got the same spectrum plot
shown on the right as on my Rigol. The power
marker values agreed quite close. The TinySA
noise marker values were a bit off. The plot shows
a marker readout at the center frequency of about -22 dBm, consistant with the Rigol's measurement. I
also noted that using bandwidths other than the recommended 30 kHz, the correction factor change of 5
dB did not track as the shape factor of the TinySA's other band-widths were probably not the same as
the Rigol's.
Adjusting Drive Level to Transmitter Power Amplifiers:
Again I refer directly to Fischer's book, section 21.7, pages 446-449.
21.7 Measuring the Shoulder Attenuation
"The system does not utilize the full channel bandwidth, i.e. some of the 2K or 8K subcarriers are set to
zero so that no interference to adjacent channels will be caused. Due to nonlinearities, however, there
are still outband components and the effect on the spectrum and its shape has given rise to the term
‘shoulder attenuation’. In the Standard, the permissible shoulder attenuation is defined as a tolerance
mask. Fig. 21.30. the spectrum of a DVB-T signal at the power amplifier output, i.e. before the mask
filter. To determine the shoulder attenuation, different methods are defined and especially a relatively
elaborate method in the Measurement Guidelines [ETR290]. In practice,the DVB-T spectrum is in
TV Rptrs Rptr-135.doc ( 7/6/23, kh6htv) p. 9 of 11
most cases simply measured by using three markers, setting one marker to band center and the others to
+/- (DVB-T channel bandwidth/2 + 0.2 MHz). With an 6 MHz channel, this results in test points at +/-
3.2 MHz relative to band center. ..... The DVB-T standard [ETS 300 744] defines various tolerance
masks for various adjacent channel allocations.
In practice, the following shoulder attenuations are achieved:
• Power amplifier, undistorted: approx. 28 dB
• Power amplifier, equalized: approx. 38 dB
• After the output BPF: approx. 52 dB (critical mask)"
Editor's Comments: Fisher is describing a typical high power, broadcast TV transmitter. The rf
drive level is first brought up until the shoulder break point hits -28 dB. What he then means by
"equalized" is then turning on an electronic feed-back, digital pre-distortion equalizer in the driver
which results in lowering the shoulder break points by 10 dB to about -38 dB. What he calls the
"Mask Filter" is what we ATV hams refer to as our Band-Pass, Channel Filter. The commercial folks
use really great filters with very close in, steep roll-off skirts to achieve the desired commercial result
of -52 dB shoulder attenuation. I doubt that any DATV transmitter comes this close to perfection.
Typical Amateur, 70cm, 10 Watt (+40dBm), DVB-T Transmitter's RF Output Spectrum
DATV Amplifiers: I am unaware of any amateur TV operation which uses electronic, digital predistortion
on their transmitter amplifiers to reduce out of channel spurious shoulders. For our ATV
repeaters, we do however, try to always use ATV channel filters on the outputs of our transmitters.
There is always a fine line to draw between wanting to drive our amplifiers to get the maximum
possible RF output power and yet radiate a clean, distortion free signal. So what should we shoot
TV Rptrs Rptr-135.doc ( 7/6/23, kh6htv) p. 10 of 11
for ? In general, the commonly accepted practice for DATV amplifiers is a shoulder break-point of
about -30 dB relative to the in-channel power level.
The above plot shows a typical DATV transmitter running QPSK modulation. The RF output power
was measured to be 10 Watts average. If this same amplifier were driven hard into saturation for FM
service, it would put out about 70 Watts. Thus for DATV service we are getting about 8.5 dB less
power. This is our Crest Factor.
I have run comparisons for the three different DVB-T modulations (constellations) of QPSK, 16QAM
and 64QAM. Using a Hi-Des HV-110 receiver's built-in diagnostic capability for decoded Signal /
Noise ratio (S/N), I was able to reliably determine at what level of drive, the amplifier started to
degrade the quality of the transmitted signal. Under ideal conditions, the S/N max. is 23 dB, 26 dB
and 32 dB respecively for QPSK, 16QAM and 64QAM. I found that I got the same results for either
QPSK or 16QAM of no degradation of S/N for shoulder break-point of the order of -30 to -32 dB.
For the more complex waveform and constellation of 64QAM, I needed to back off the drive power
level by 1 dB with an attendant shoulder break-point of the order of -32 to -34 dB. Thus the RF output
power was also 1 dB less, implying the need for a higher crest factor, also by 1 dB of at least 9.5 dB.
73 de Jim, KH6HTV, Boulder, Colorado
W0BTV's RFI: Jim --- You can solve your RFI 70 cm ATV problem if you switch to Horizontal
polarization. ---- Cheers, Dave P. AH2AR
BATVC's Reply: --- Yes, Dave is correct. The dominant signals seen on the 70 cm band, which
are causing our RFI grief to our repeater are predominantly vertically polarized. Going to horizontal
polarization would buy us an additional 20 dB of isolation. However, we need to go back in our
history. The major compelling reason we ever started ATV in Boulder in the first place back in 1990
was for ARES purposes to support our local Sheriff's department. In return, the Sheriff provided
funding, plus a location and tower access for our ATV repeater. The ARES field ATV units would be
carrying their gear in back packs and using vertical whip antennas, or operating mobile units, again
with vertical whip antennas. Hence the repeater needed to support vertical polarization. Support for
ARES and the OEM and Sheriff are still today, the major reason for us having ATV (now DATV) in
Boulder. Without our providing emergency comms capability to public safety agencies, we would
probably not be able to continue to occupy our excellant repeater site.
TV Rptrs Rptr-135.doc ( 7/6/23, kh6htv) p. 11 of 11
W0BTV Details: Inputs: 23 cm Primary (CCARC co-ordinated) + 70 cm secondary
all digital using European Broadcast TV standard, DVB-T 1243 MHz/6 MHz BW (primary),
plus 439 MHz/6 MHz BW and 439 MHz/2 MHz BW
Outputs: 70 cm Primary (CCARC co-ordinated), Channel 57 -- 423 MHz/6 MHz BW, DVB-T
Also, secondary analog, NTSC, FM-TV output on 5.905 GHz (24/7 microwave beacon).
Operational details in AN-51c Technical details in AN-53c. Available at:
W0BTV ATV Net: We hold a social ATV net on Thursday afternoon at 3 pm local
Mountain time (22:00 UTC). The net typically runs for 1 to 1 1/2 hours. A DVD ham travelogue is
usually played for about one hour before and 1/2 hour after the formal net. ATV nets are streamed live
using the British Amateur TV Club's server, via: Select ab0my or n0ye. We
use the Boulder ARES (BCARES) 2 meter FM voice repeater for intercom. 146.760 MHz ( -600 kHz,
100 Hz PL tone required to access).
Newsletter Details: This is a free newsletter distributed electronically via e-mail to
ATV hams. The distribution list has now grown to over 500+. News and articles from other ATV
groups are welcomed. Permission is granted to re-distribute it and also to re-print articles, as long as
you acknowledge the source. All past issues are archived at:
Free advertising space is offered here to ATV hams, ham clubs
or ARES groups. List here amateur radio & TV gear For Sale -
or - Want to Buy. ... tr-135.pdf
Prispevkov: 1012
Pridružen: 28 Okt 2004, 21:07

Re: revija ATV

OdgovorNapisal/-a s58ru » 20 Jul 2023, 11:52

TV Rptrs Rptr-136.doc ( 7/16/23, kh6htv) p. 1 of 14
Boulder Amateur
Television Club
TV Repeater's
July, 2023
3ed edition, issue #136
BATVC web site:
ATN web site:
Jim Andrews, KH6HTV, editor -
Merelda, VP6MW & Mike, VP6MC (WA6SVT)
ATV HAM Installs DTV Transmitter
on Pitcairn Island
Mike Collis, WA6SVT (VP6MC)
TV Rptrs Rptr-136.doc ( 7/16/23, kh6htv) p. 2 of 14
Aloha Jim ---- My family and I are back from our recent trip to Tahiti and Pitcairn Islands. The
above photo is of Merelda Warren, VP6MW, and I wearing our Amateur Television Network (ATN)
shirts at the Picairn boat landing. Merelda is the resident ham on Pitcairn. He was born and raised on
the island and is a 7th generation Bounty descendant.
Ran HF at times. Very good DXing especially to Europe. I also met up with some of the VP6A, DX
expedition from Ducie Island. They stopped by Pitcairn on their way back home.
ZBTV is Pitcairn Island's first Digital TV station.
UHF channel 25 (506.0 MHz) DVB-T at 8 MHz
bandwidth. Power output is 8 watts and covers
Adamstown. Programming is ABC-Australia on
IS-18 satellite using a 6 meter dish. I donated the
transmitter and my time working with Jay Warren
and Kerry Young. Improvements planned will be
an upgrade from a coax feed line to Heliax.
Many years ago the pastor of their church at the
time installed a home satellite dish and a 5 watt
analog channel 21 TV transmitter for the Hope
channel. The old system was hit by lightning and
the dish was rusting to the point it was no longer
usable. The system lay idle for several years. I
took the four bay panel antenna apart and
performed a full rebuild including modification for
the tropical environment to reduce the chance of
internal and external corrosion. The old feedline is
LMR-400. I had to cut off 45 feet as the end of the
line was left to the weather and it took it's toll on
the coax. Loss is still not so good at 7 dB for 160 ft
run. The old run was 205 ft.
New heavy duty pole is now located closer to the equipment vault and high enough to clear the ridge to
see into Adamstown. New Heliax is ordered from New Zealand. Transmitter is a Hi-Des HV-320 and
an RA45H4452M, LDMOS power module. The amplifier has over temperature, voltage and SWR
protection circuit.
The old defunct TV system was never licensed. This is the first commercial communications license
issued since just after World War Two when Pitcairn had ZBP marine ship to shore and a government
shortwave radio station. I helped the Pitcairn government with generating a license for their TV
station. The ITU designates the prefix for various countries and ZB is for commercial licenses. The
county then selects the suffix.
TV Rptrs Rptr-136.doc ( 7/16/23, kh6htv) p. 3 of 14
Refurbished UHF Transmitter Antenna Antenna VSWR after rebuilding
Since this is a TV station, then TV is what we
chose for the suffix. The Pitcairn government has
issued ham radio licenses for years but this is the
second commercial license in a century. The vault
is shared with USGS earthquake monitoring
station. The vault is mostly underground with one
side open. The 6 meter dish is new and was
installed about two years ago. We finished the
install by connecting the feed system LNB and
conduit - IF cable run.
RF Spectrum of New Transmitter
Most of the residents have smart TV sets to stream online video. Although this worked, it tended to
clog up the internet. With the addition of ZBTV, there is much less clogging of the internet now. The
general store had several new in the box, UHF TV receive antennas from old times and when ZBTV
came back on the air and the word was out that it worked, the antennas sold out in an hour's time!
73, de Mike, WA6SVT (VP6MC)
ZBTV transmitter antenna on crest of hill as seen from the boat landing
TV Rptrs Rptr-136.doc ( 7/16/23, kh6htv) p. 4 of 14
70 cm RFI is Gone !
( maybe ? )
6 July - Boulder, W0BTV Repeater, ATV Net Well, we finally, after a long spell have good
news to share with our readers. Our ATV net today was flawless. Everyone got into the repeater
with great signals and NO Freeze Frames ! Everything worked well on all three of the repeater's
inputs of 23cm (1243 / 6 MHz) and the troublesome 70 cm inputs of 439 / 6 MHz and also 439 / 2
TV Rptrs Rptr-136.doc ( 7/16/23, kh6htv) p. 5 of 14
We started with Don, net control, on 439/6 with a perfect 23dB s/n and -58dBm signal strength at the
repeater's input. Pete & Debbie on 439/6 with a perfect 23dB s/n signal of -70dBm. Steve, from up
on Sugar Loaf Mtn., then followed via his WA0TQG-TVR (23/70cm) repeater with a 439/6, 23dB s/n
signal of -56dBm. Next up was Jack with a narrow-band 439/2 of -70dBm, but still 23dB s/n. Don
then tried 439/2 MHz and put -60dBm, 23dB s/n into the repeater. Then Jim from way out east of
town tried 70cm instead of his usual 23cm input. On 439/2, he put in -79dBm with 20dB s/n, while on
439/6, he put -78dBm with 17dB s/n into the repeater. Everyone's digital picture was P5 perfect with
Q5 CD quality audio and no break ups, nor freeze frames. Yeah ! ! !
So what changed ? ? ? --- We don't know at this point. As long as the RFI stays away, I guess we
now don't care. At least we proved the basic repeater is still working fine.
73 de Jim, KH6HTV, & Don, N0YE, W0BTV Trustees
WB0CMC -- Omaha, Nebraska
ATV Repeater Update
ATV BACK ON THE AIR. All the equipment was put in the rack on July 3 and mostly hooked
up. I discovered that there was only one outlet not used so had to go back on the 4th with a plug strip. I
finished hooking everything up and re-checking all of it and turned it on. No breakers popped, an
important test since the power supply for the amplifier has a 0.1 FARAD filter capacitor at 50 Volts and
TV Rptrs Rptr-136.doc ( 7/16/23, kh6htv) p. 6 of 14
a 0.025 Farad at 16 Volts. Big in-rush. The system still works pretty much like it used to but with
some nice additions. One of the color bars (*) now has a 400 HZ tone audio with it at 25 KHz
deviation. There is also a camera available with a mic that’s hot when the camera is on (Lots of noise
from the FM transmitter blowers). The camera is inside the building so it’s just more of a security
thing. There is an important addition to the 434 MHz receiver. It is either analog like it used to be or
digital. The digital format is DVB-T, a European format used by nearly all US digital ATVers. It’s a
good format and one of the cheapest around for the equipment. Both recievers use the same antenna
and input filter. There is a priority switch that selects the A-V signal (both analog) and transmits it in
NTSC. The repeater is running right at 200 watts sync power. The digi RX has an analog output:
NTSC with stereo audio if desired (both channels combined, so watch audio phasing if you’re using
both audios.) The pattern generator (just a “jim-crack”but kind of neat) has a crystal controlled time
base instead of the original R-C one. Control freq is still the same. NO PL required. If you want to
see if you can receive the repeater, key in the access code. This should get you color bars with ID
super-imposed. Don’t forget to ID on the voice repeater when you’re done. # shuts every thing back
off or it will time out in around 15 or so minutes as well. The repeater IDs itself every 10 minutes or so
by a video super-imposed. With ATV a legal ID can be either audio (voice) or video (hold up a sign or
put it in the back ground of your picture or use a super if you have the equipment) or both. Take your
pick. If anyone wants the digi format parameters, I’ll be happy to send them your way. For more on
this and digi stuff see and . All three antennas are about 350 feet
above ground and on the highest hill within the city limits so coverage should be good for quite a long
way's away. It was before so coverage won’t change much if at all.
73 de John, WB0CMC
In a seperate location on the cable tray is the receiver's ATV channel filter. Not visible in the photo are
the analog and digital receivers. The 435.5 MHz channel filter has 0.5 dB insertion loss in the pass
TV Rptrs Rptr-136.doc ( 7/16/23, kh6htv) p. 7 of 14
band, 7 MHz band-width and 70 dB rejection ± 1 MHz on either side of the pass band. Note the size
of the coax cables coming out of the ceiling which are going to the antennas !
Photo on the left is the front view of the Omaha, Nebraska, 70 cm, WB0CMC-ATV repeater. The
equipment in the rack from top to bottom consists of: top, ATV channel filter with 1/2 dB insertion
loss and 6 MHz pass band. Next down is the 250 Watt amplifier set for 200 Watts NTSC, analog sync
power. Next rack i s the controller and 5 Watt exciter. At the bottom is the color bar generator with
ID superimposed.
Photo on the right is the rear view of the repeater rack. At the top is the ATV channel filter with an
isolator. Next down is the rf power amplifier. Next is the controller and the bottom is the color bar
Editor's Note: Whow ! What an impressive repeater. Plus it's location is to die for.
TV Rptrs Rptr-136.doc ( 7/16/23, kh6htv) p. 8 of 14
Thermal Study
and Cures
for HV-320E
Jack, K0HEH & Jim, KH6HTV
Back in 2017, when Hi-Des had come out with some of their newer products, including the HV-320
modulator and their HV120 receiver, we had purchased them and then discovered that they really didn't
like to work outside of an air conditioned, lab envirornment. Taking them out in the field and
exposing them to direct sunshine caused them to mal-function. At the time, our solutions were to add
rubber feet on the bottom of the metal enclosures to allow air to circulate under the boxes, plus add a
muffin fan to the top of the box. This was documented in the app. note, AN-37 "Thermal Issues with
Hi-Des, DVB-T Equipment". Shortly after AN-37 was published, Hi-Des then modified the design
of the HV-320. They added rubber feet and drilled ventilation holes in the plastic front cover and
installed a miniture 20x20mm muffin fan in the front cover. Current production HV-320s come with
this fan installed. We thus withdrew our AN-37 from our web site as it was no longer necessaray.
In the more recent past, Jack, K0HEH, began to have considerable grief with his old Hi-Des, model
HV-100EH, DVB-T modulator. It put out very intermittant signals. Essentially unusable. Jack then
invested in an infa-red thermal measuring gun. The inexpensive ($20) gun he found at Harbor Freight
included a spoting LED red dot projector and a very narrow measurement beamwidth. (bar code#
92363-69465, spot size = 8:1)
Jack was thus able to determine the actual case temperature of each and every IC in his HV-100. With
this he was able to ID which devices were running the hottest and thus was most suspect to be causing
his trouble. Jack then found at some extremely tiny finned heat sinks intended to be
attached directly to ICs. They included thermally conductive adhesive strips for attachment. Jack did
a wholesale treatment adding heat sinks to several ICs. Using these solved Jack's HV-100 thermal
problem. Jack purchased both 8x8mm and 14x14mm finned aluminum heat sinks. MPJA sells them
for $3 for a package of 10. (8mm p/n 35610-HK, 14mm p/n 35615-HK)
Last year, Jim, KH6HTV, had purchased a new HV-320E. Recently the 20x20mm muffin fan failed in
it. Jim, removed the fan and attempted to run the unit just relying upon natural convection via the
front panel holes. But the case ran quite hot and after some time of operating (in normal ham shack
TV Rptrs Rptr-136.doc ( 7/16/23, kh6htv) p. 9 of 14
temp), the output became flaky and unusable. So Jim, checked with Digi-Key. A 20x20mm muffin
fan replacement cost about $16. But Jim thought as long as I am replacing it, why not go with a
larger, less expensive fan. Maybe it might also be quieter. The tiny 20x20mm fan created an
annoying level of noise in the ham shack. Discussing this on the W0BTV weekly ATV net, Jack than
suggested Jim also try his heat sink solution. So now, the HV-320 will be cooled both using added mini
heat sinks and also a larger muffin fan. The 50x50mm muffin fan creates a "hurricane" level of air
flow, but also considerable noise when run off of the normal (12-13.8Vdc) supply. It was found that
using a series 150 Ω resistor slowed the fan down and made it much quieter and still gave a nice flow
of air, much more than with the original tiny 20x20mm fan. A circular pattern of holes were drilled
in the top surface of the metal enclosure. The fan was mounted, along with a finger guard using 6-32
screws. The above photo shows the HV-320 with the new 50mm fan installed along with the tiny
20mm fan sitting in front.
Before making any mods to the HV-320 pc board, we first used Jack's IR temp gun to study the
temperature of individual ICs on the HV-320 pc board. The board was operated out in free air, laying
on the work bench. The two photos of the top and bottom of the pcb show the measured temperatures.
One IC, U9, in particular had an extra hard thermal radiatior pad already attached to it by Hi-Des. It
was near the SMA output jack and was probably the RF output stage ?? Even with this radiator, it's
temperature measured 47oC. Several other ICs on the board were also running quite hot. Hot
enough to burn your fingers ! It should be noted that ICs are mounted on both the top and bottom of
the pc board. On the bottom of the board, there were some large metallized areas used as ground
planes and also heat radiators. The one in the center of the board, underneath the largest IC, U7,
measured 67oC. The larger ground plane near the SMA RF output connector measured the hottest at
73oC. With this much heat on the bottom of the board, we than also decided we needed to add a few
ventilation holes to the bottom of the HV-320 metal enclosure.
TV Rptrs Rptr-136.doc ( 7/16/23, kh6htv) p. 10 of 14
We added the aluminum, finned heat sinks to three
of the ICs. The largest, custom ITE IC, U7, in the
center of the board got a 14x14mm heat sink.
Smaller ICs, U9 & U10, got 8x8mm heat sinks.
The remaining hot ICs and transistors were too
small to attach even the 8x8mm heat sink.
The 50x50mm, 12Vdc fan, plus the 150 Ω resistor were wired directly to the +12 Vdc power input
jack. With the series resistor, the fan only pulled about 30 mA of current. The previous large hole on
the plastic front panel where the original tiny fan was mounted was left open as an exhaust hole for the
circulating fan air. Now in operation, the fan noise is very quiet and the metal enclosure runs very
cool to the touch. The modified HV-320 was then run for 24+ hours as a burn-in test and performed
Advice for Repeater Builders: If you are planning to build a DVB-T repeater using the Hi-
Des modulator or receivers, then we advise you to take extra special precautions relating to thermal
cooling. Repeaters are most often in out of the way, un-attended locations, sometimes in unheated or
uncooled shacks exposed to weather extremes. Plus all of the equipment in a repeater rack is running
continously 24/7 for months/years on end. Failures can be costly. So, we suggest that you add these
extra heat sinks and larger cooling fans to the Hi-Des gear. Plus any other suspect parts that develop
any appreciable heat in normal operation. Such as a Raspberry-Pi, etc.
73 de Jack, K0HEH & Jim, KH6HTV, Boulder, Colorado
International ATV QSO Party: On the last Friday and Saturday of
August, I will anchor a DATV QSO Party based out of Melbourne Australia. Our local DATV Repeater
VK3RTV has an SRT input which is a superior technology to RTMP. It is also possible to use Zoom as
a mechanism. Zoom will be used as a Back Channel for event control. The best option is for an
Anchor to manage inputs to a local Repeater and then forward the output of the Repeater either by
direct SRT or Zoom. The international component initially starts on the east coast of the USA and
moving with the timeline to the west coast. Later in the day stations in Europe can also participate. I
am looking for any individual stations that may like to participate and also anyone that could act as a
local Anchor.
VK3RTV is the Melbourne DATV Repeater in Australia with a two channel, multiplexed, DVB-T2
output on 445.5 Mhz. VK3RTV also streams via the BATC when it is active. 23 cm Inputs are both
DVB-S/S2 and DVB-T.
Anyone interested please contact myself, Peter, VK3BFG, at
TV Rptrs Rptr-136.doc ( 7/16/23, kh6htv) p. 11 of 14
MICROWAVE ATV: Don, N0YE, is getting cabin fever now that nice weather
has finally arrived in Boulder, Colorado. So at our July 6th ATV net, he started talking up our taking
our microwave ATV gear out in the field once more for ATV-DXpeditions. He did an on the air
survey of what bands folks had gear available for. At this point, the most number of ATV hams have
gear for 5.8 GHz, analog FM-TV. So, it looks like our first outing will be using this gear. Don has
thus scheduled next Saturday morning, the 22ed for the first one. For future outings, later this
summer, we will explore using DVB-T on one or more other bands of 1.2, 2.4, 3.4, 5.8 or 10 GHz.
As a reminder, you can check out ahead of time your 5 GHz, FM-TV receiver and antenna with our
W0BTV repeater's beacon on 5.905 GHz. It transmits an NTSC analog signal 24/7.
W0BTV - RFI: Nice newsletter Jim! At your repeater site, are there any 2 meter repeaters? If so,
if close mounted antennas to your 440 MHz ATV antenna takes place the 3rd harmonic of a 2 meter
repeater will kill your ATV RX. I had the issue years ago at Santiago Peak and gave a LPF to the 2
meter repeater owner and that stopped the issue.
73, Mike, WA6SVT, ATN-S.California
Vertical vs. Horizontal Polarization ( the never ending debate ! ): Jim --- There
really is nothing stopping you from switching to horizontal polarization and also being able to still
support public services. The 20dB isolation that you will achieve from the other 70cm users would
actually help greatly in creating a useable link during emergencies. There are several omni-directional
horizontally polarized portable antenna designs that are easily fabricated. But much more importantly,
if someone was really serious in supporting emergency services, they should, at minimum, be using a
tripod and Yagi antenna out in the field. Trying to depend on a whip antenna to close the ATV repeater
link, especially when it is unknown at what location an emergency will occur is extremely sketchy at
best. Whips are fine for FM repeaters but will fall short for ATV if the path has much obscura. I would
think that the more likely reasons for not switching to horizontal polarization is the trouble people will
have in changing their local antenna installation, for non-emergency ATV repeater use. Of course, it
also takes some planning and metal bending to fabricate an efficient slot (or rib cage) antenna for the
ATV repeater site. Such a project is doable.
Cheers, Dave, AH2AR, DARA
W0BTV Reply: Dave --- Thanks for your comments. Much appreciated. Our Boulder ARES
group does in fact have and uses YAGI antennas when needed. They along with antenna tripods, masts
and coax are all stored in our equipment cache along with all our other emergency comms gear at our
911 center with 24/7 access. Our gear also includes a portable, 10 Watt, 70cm, DVB-T repeater.
BUT for many operations it is roving feet on the ground moving around, not stationary, hence the need
for vertical whip antennas. The whips are not buried in back packs with the transmitters, but are
attached to the camcorder tripods up in the clear away from rf absorbing bodies, etc. There have been
some operations when net control wanted the TV camera crew moving quite rapidly from one location
to another. Not enough time to redeploy a complete yagi system. ------- 73 de Jim, KH6HTV
TV Rptrs Rptr-136.doc ( 7/16/23, kh6htv) p. 12 of 14
RE: Hi-Des Receiver’s HDMI Your issue with HDMI output “might be” resolved with
firmware version ... 6n5lsfmLEa?
dl=0 (V0. HDMI driving value) for the HV-110. Have you tried it? I assume you
have, but if not, maybe it would work with all your monitors. I also assume too you have “Low
Latency mode” set to OFF. ON is the default for the low latency firmware only and it can (dependent
on video being received) seriously degrade the video. However, even with it ON, the video out should
never go “black..” Another thing ☹ to try assuming you have not already… connect an analog
monitor up and hit the “SUB” button on the remote. It should switch you to the analog CVBS port and
display 480p. You have to toggle power as it looks for that port first on boot up (I think). If it does not
output video right away, try repeated button pushing of the SUB button. I have had the -110 and 120
output video at the same time with different resolutions. Maybe the receivers always would do this as
I have not played around with CVBS much in the past. The “latest” production -110s I have are a
couple I received after the $99 ones were no longer available. These were bought at the current price
of $119.
Thanks again for the newsletter. Always look forward to reading it. 73 de Mel, K0PFX, St. Louis, MO
W0BTV Details: Inputs: 23 cm Primary (CCARC co-ordinated) + 70 cm secondary
all digital using European Broadcast TV standard, DVB-T 1243 MHz/6 MHz BW (primary),
plus 439 MHz/6 MHz BW and 439 MHz/2 MHz BW
Outputs: 70 cm Primary (CCARC co-ordinated), Channel 57 -- 423 MHz/6 MHz BW, DVB-T
Also, secondary analog, NTSC, FM-TV output on 5.905 GHz (24/7 microwave beacon).
Operational details in AN-51c Technical details in AN-53c. Available at:
W0BTV ATV Net: We hold a social ATV net on Thursday afternoon at 3 pm local
Mountain time (22:00 UTC). The net typically runs for 1 to 1 1/2 hours. A DVD ham travelogue is
usually played for about one hour before and 1/2 hour after the formal net. ATV nets are streamed live
using the British Amateur TV Club's server, via: Select ab0my or n0ye. We
use the Boulder ARES (BCARES) 2 meter FM voice repeater for intercom. 146.760 MHz ( -600 kHz,
100 Hz PL tone required to access).
Newsletter Details: This is a free newsletter distributed electronically via e-mail to
ATV hams. The distribution list has now grown to over 500+. News and articles from other ATV
groups are welcomed. Permission is granted to re-distribute it and also to re-print articles, as long as
you acknowledge the source. All past issues are archived at:
TV Rptrs Rptr-136.doc ( 7/16/23, kh6htv) p. 13 of 14
Free advertising space is offered here to ATV hams, ham clubs
or ARES groups. List here amateur radio & TV gear For Sale -
or - Want to Buy.
Here is a Selection of Some Items Listed For Sale or Give Away
For details, see the SLATS' web site
Icom ID-1 23cm Digital Transceiver PTZ Controller & Control Head
TV Rptrs Rptr-136.doc ( 7/16/23, kh6htv) p. 14 of 14
Registration is now open for the 2023 Rocky Mountain Division
Convention in Albuquerque, NM August 11-13, 2023. The
Very Large Array (VLA) tour is going to be phenomenal !
General Convention Information: ... tr-136.pdf
Prispevkov: 1012
Pridružen: 28 Okt 2004, 21:07

Re: revija ATV

OdgovorNapisal/-a s58ru » 21 Jul 2023, 21:34

TV Rptrs Rptr-137.doc ( 7/19/23, kh6htv) p. 1 of 12
Boulder Amateur
Television Club
TV Repeater's
July, 2023
4th edition, issue #137
BATVC web site:
ATN web site:
Jim Andrews, KH6HTV, editor -
899 km on 3cm DATV !
Hi Jim, my name is David IW9GUR. Last July 9, during an Italian
DATV contest "CONTEST ATV TRIVENETO" I managed to make
a bidirectional DATV connection in 3cm with the IZ5TEP station
from Sicily to Liguria covering a distance of 899km. I'm sending
you the link to view images and videos on the NET ITALIA
Facebook page. if you want to highlight this news in your newsletter,
you will find the details of the link in the post. thanks
73 de IW9GUR, David ... 201902423/
TV Rptrs Rptr-137.doc ( 7/19/23, kh6htv) p. 2 of 12
I (Jim, KH6HTV) play tennis with lots of older, retired fellas. Everyone of them has an interesting
background from many different careers. Recently, I found out that one of them had actually worked
on developing a scheme for digital TV way back in 1960. Ken Hacket was a recent college grad at
the time. He first worked for a couple of years at Lawrence Livermore Labs in California. Then he
took a job in Boulder, Colorado working for a new aerospace company here called Ball Brothers
Research Corp. The company is still in existance today in Boulder and is now called Ball Aerospace
& Technologies Corp. They produce space systems engineering products, telecommunications
technology, electro-optics and cryogenics materials for government and commercial customers. For
Ken's first job with Ball he was assigned to a group developing digital TV. Here is Ken's own story.
"Our digital TV back the 1960s was quite primitive compared to what they are doing today. The
primary purpose was to digitize TV so it could be encrypted and yet produce a useable picture for
military briefings between facilities in a region. Mainly around Washington DC via microwave links.
In those days there were no microprocessors and large fast memories. And no integrated circuits of any
kind. There were large mainframe computers, but they were impractical for our use. Because of the
unavailability of memories fast and large enough to store a single frame of video, we could not even
think about manipulating the image like MPEG which had not been invented yet. We operated in realtime
using delta modulation or delta-sigma. We simply transmitted one bit at a time: 1 was an
increment up, 0 was an increment down. A constant level of grey would produce a series of 1s and 0s.
The resulting image reconstruction was pretty rough by today's standards. However, the eye and the
persistence of the phosphor on the video screen did a remarkable integration job providing a useful,
relatively noise free image.
We started out with a system operating at 10 Mb/sec; later 30 Mb/sec. Finding components that
operated at that speed then was challenging. We had to make a 1/0 decision within one bit period. We
found the only thing that was fast enough then was a tunnel diode.
I have attached a copy of the patent that was issued
for the A/D converter we developed. It was
developed in about 1960-62. The patent was issued
in 1966. There is a painful amount of detail in it. As
you can see, all we had to work with was discrete
components. In any of our literature we had to be
very careful to not use the word "encrypted". We
were absolutely forbidden to use it. We could use
"scrambled". It's kind of funny nowadays since that
word is used everywhere."
TV Rptrs Rptr-137.doc ( 7/19/23, kh6htv) p. 3 of 12
view toward W0BTV from Canine Ridge
W0BTV, 5 cm, FM-TV Beacon seen at 86 km !
Gary, WB5PCB, has been doing some roving recently with his 5 cm ATV gear. Our Boulder,
Colorado W0BTV-ATV repeater includes a 24/7 beacon transmitter on 5.905 GHz with a 2 Watt, FMTV
signal to a 10 dBi, omni-directional antenna. Today (7/18), Gary sent us this following report.
"Aloha, Jim. Well, I have the stuff in the car, so I figured I would do some testing from places other
than Daniel's Park. And, to that goal, I stopped on my way home this afternoon at a spot that I thought
might have a chance of receiving the 5.8 GHz beacon. And, I got a signal at 53.2 miles (85.6 km)
between NCAR and what I call Canine Ridge. It's in a private community south of Castle Rock. If I can
go any further south, it might be close to the Douglas and El Paso county border. Of course, I guess I
could go to the top of Pikes Peak and have a good chance."
TV Rptrs Rptr-137.doc ( 7/19/23, kh6htv) p. 4 of 12
How to Build a Simple, Digital TV Repeater
The Boulder, Colorado ARES group BCARES was blessed for several years by having a member we
called "Mr. Television". He was Matt Holiday, K0DVD. I guess his personalized vanity call sign
gives away his main ham radio interest ! Matt was the resident TV expert and co-ordinator for all of
BCARES's ATV operations. He also built and donated some of the DATV equipment. One of his
biggest and most expensive donations was a portable, 70cm, DVB-T Repeater. We are reproducing
here the instruction manual for Matt's repeater. This might give other ham clubs and ARES groups
elsewhere some ideas on how to contstruct a similar repeater.
Unfortunately, the disasterous Boulder, Colorado fire of 31 Dec. 2021 (called the "Marshall Fire")
which destroyed over 1000+ homes, also destroyed Matt's home. As a result, Matt pulled up stakes
and has since moved away from Boulder. We were sorry to see Matt go.
To find out more about Matt, check out his web site at: Matt had started to
document a lot about DATV and ARES there. Matt also put together several excellant training
classes for members of BCARES to teach them both the fundamental theory of DTV and also the
operational details of setting up and using the BCARES, DATV equipment. Copies of the powerpoint
slides Matt prepared for ATV training classes in 2018 are available on the BCARES web site at: ... mateur-tv/
70 cm, Portable
DVB-T Repeater
Instruction Manual
Revision: July, 2023 by KH6HTV
TV Rptrs Rptr-137.doc ( 7/19/23, kh6htv) p. 5 of 12
Fig. 1 Front Panel of the Repeater with the cover removed
BCARES has a digital Television Repeater which is portable and can be deployed to remote locations
such as mountain tops. It was designed, built and donated to BCARES by Matt Holiday, K0DVB.
The repeater is compatible with the BCARES digital ATV pack sets which were donated by the
University of Colorado Police dept. It operates on the 70cm amateur radio band ( 420 - 450 MHz).
The input frequency is Channel 06 ( 439 MHz, 6 MHz band-width 436-442 MHz). The output
frequency is Cable Channel 57 ( 423 MHz, 6 MHz band-width 420-426 MHz). The repeater uses the
European Digital Broadcast TV Standard called DVB-T. The repeater's output power is 5 Watts
Note: July, 2023 Revision consisted of changing the input frequency from 441 to 439MHz. This was
done in an attempt to move away from some local RFI. It required retuning the input band-pass filter
and reprogramming the receiver. kh6htv, 7/15/2023
Fig. 2 70 cm, Digital TV Repeater, block diagram.
ANTENNAs: Fig. 2 shows the basic block diagram of the repeater. Note that it requires the
use of two separate antennas. One for receive and one for transmit. Most typical 2m & 70cm FM
voice repeaters use a single antenna and duplexer. The antennas must be separated from one another
and not pointing at each other. See Fig. 3. Connect the antenna cables to the Band-Pass Filters on the
rear panel, Fig. 4.
TV Rptrs Rptr-137.doc ( 7/19/23, kh6htv) p. 6 of 12
Fig. 3 Portable TV Repeater using Yagi Antennas. The secret to a repeater is high isolation between
the transmitter and the receiver.
Fig. 4 Antenna Connections are found on the rear panel of the repeater.
The repeater is run off of +12 Vdc power (+13.8V is OK). In
stand-by mode, it draws 0.9 Amps. When transmitting, it draws 9
Amps. Connect a suitable power source to the front panel
Anderson Power-Pole connector. It is located in the center
bottom and labled "12V DC 10A".
The master DC power switch is labeled "Main Power". It is
located on the front panel and covered with a blue protector.
Fig. 5 DC Power Connection
TV Rptrs Rptr-137.doc ( 7/19/23, kh6htv) p. 7 of 12
Optional Accessories:
If a video monitor is available, it is connected to
the "TV Out" connector on the front panel via an
HDMI cable.
If a TV camera is available for producing video
locally at the repeater site, then it is connected to
the "Camera" connector on the front panel via an
HDMI cable.
The USB "Control" connector on the front panel is
not used. It is only used for maintenance purposes
to modify the digital parameter settings in the
modulator. Fig. 6 Front Panel - Right Side
VIDEO SELECTOR SWITCH: Also seen in Fig. 6 in the middle is an HDMI Video
Matrix Switch. It has 2 inputs and 2 outputs. Output #1 goes to the repeater's modulator. Output #2
goes to the external video monitor. Input #1 is from the repeater's receiver. Input #2 is from the
external video camera. Push buttons for each output select the desired input. LEDs show which input
is selected.
IMPORTANT ! For normal TV repeater operation, the Modulator video output must be set to input
#1, the Receiver.
If you want to transmit video from your local camera, then the Modulator video output is set to input
#2, the camera.
Fig. 7 Main Repeater Controls
The main repeater control panels are located on the small 19" panel. There are two, heavy duty, DC
toggle switches labeled "Main Power" and "Amplifier". Set both of them to the ON position.
CAUTION: Do NOT turn on the DC power until a proper antenna is connected to the transmitter.
Failure to have an antenna connected will result in destroying the final RF power amplifier.
The only other control is the 3 position, toggle switch seen in Fig. 7 on the left. The LED next to it
shows the repeater's transmitter status. Yellow = Stand-By & Red = Transmitter ON.
TV Rptrs Rptr-137.doc ( 7/19/23, kh6htv) p. 8 of 12
For Normal Repeater Operation -- set the toggle switch to the up position, "AUTO RPTR". In this
position, the transmitter is in stand-by mode until a valid digital TV signal is received. When the
receiver recognizes such a signal, it puts out a "Valid Signal" logic which then automatically switches
on the repeater's transmitter. When the signal disappears, the repeater turns off again. Remember, for
repeater mode, you must also set the HDMI matrix switch output #1 to input #1, receiver.
For Local Repeater Operation --- When generating your own local video signal with your camera,
you turn on the transmitter by setting the toggle switch to the down position "XMIT". Remember, if
you want to transmit your own local video, you must also set the HDMI matrix switch output #1 to
input #2, camera.
FCC ID: This is a simple repeater. It does not include a time-out timer, nor a squelch tail IDer,
nor a Morse code IDer. However, the repeater is IDed continuously. As part of the digital
information sent out along with video and audio is a meta-data file with information about the encoding
used. The meta data also includes the transmitter's call sign. The repeater has been programmed with
the BCARES call sign, W0BCR.
SUPPLEMENTAL INFORMATION: ( not required for set-up and operation )
Receiver & Modulator: The digital TV receiver and modulator are commercial units made
by Hi-Des company in Taiwan ( ). They are located on the bottom of the repeater.
See Fig. 1. They have been pre-programmed and the user should make no changes to them. Do not
touch their front panel controls. A remote control for the receiver is contained in a bag and must
always be kept with the repeater. The receiver must be left on Ch 04 ( 441 MHz / 6 MHz BW ). The
modulator is programmed via USB with a Windows PC. The modulator must be left on Ch 57 ( 423
MHz / 6 MHz BW ).
The receiver has been programmed to provide a 720P, HDMI output with a constant On-Screen-
Display (OSD). It was programmed to receive the following channels: 01 = 423/6, 02 = 429/6, 03 =
435/6, 04 = 441/6, 05 = 447/6, 06 = 439/6 (repeater's input frequency), & 07 = 915/6 MHz
The modulator was programmed to have the following digital parameters: Frequency = 423 MHz,
Band-Width = 6 MHz, Video encoding = H.264, Video resolution = 1280x720, encoding bit rate = 4.5
Mbps, QPSK modulation, 8K FFT, 52/3 code rate (FEC), 1/16 Guard interval. Audio encoding =
MPEG2, encoding bit rate = 96 kbps, rf attenuation = -3dB.
Fig. 8 is a more detailed, overall block diagram of the repeater. Fig. 9 is the schematic diagram of the
PTT control circuit for the rf power amplifier. Figs. 10 & 11 are the frequency response curves for the
TV Rptrs Rptr-137.doc ( 7/19/23, kh6htv) p. 9 of 12
PRE-AMPLIFIER: The 70cm pre-amp was made by Advanced Receiver Research. ( ) It is the model P432VDG. It uses a GaAs FET. It has 20 dB of gain.
The advertised noise figure is 0.5 dB and the -1dB compression point is +12dBm.
POWER AMPLIFIER: The RF Power Amplifier was built by a radio amateur in Austria.
Darko Banko, OE7DBH. No detailed specs., schematic diagram, nor test data were furnished with the
amplifier. The amplifier includes a large heat sink and cooling fan. The rf drive level from the
modulator has been set to properly drive the final amplifier without distorting the digital signal. The rf
power output from the amplifier is about 9 Watts (average).
BAND-PASS FILTERS: The Band-Pass Filters ( BPFs ) were salvaged from BCARE's old
NTSC, analog TV transmitters. They were built in the 1990s by Spectrum International. They were
the model PSF-ATV-XXX. The company Spectrum International is no longer in business. They have
been re-tuned by Jim, KH6HTV. Figs. 10 & 11 show their frequency responses. For the Ch 60 (441
MHz ) receive BPF, the insertion loss was -1.4 dB and the -3 dB band-width was 6.7 MHz. For the Ch
57 (423 MHz ) transmit BPF, the insertion loss was -1.5 dB and the -3 dB band-width was 6.7 MHz.
The rf power output from the Ch 57 BPF is about 5 Watts (average). Note: input filter retuned to 439
MHz center frequency. IL = -1.5dB, BW = 6.7 MHz, kh6htv, 7/15/23
RECEIVER OSD: The receiver has it's on-screen-display permanently enabled. In the
upper left corner is displayed the frequency and band-width ( 441000/6 ). In the lower left corner is
the call sign of the incoming signal. Note: sometimes, the receiver fails to update this. In the lower
right corner is the Signal / Noise ratio of the decoded digital video signal. For QPSK, the max. value
will be 23 dB. For 16QAM, the max. value will be 26 dB. In the upper right corner is the S meter. It
reads the received power into the receiver's antenna in dBm. It has been found to be accurate to within
± 1 dB over a very wide range ( -80dBm to -10dBm ) The value displayed will read high due to the
gain of the pre-amp ahead of the receiver and the loss of the input BPF. A correction factor of about -
18 dB should be applied to the displayed value to determine the actual input signal level at the
repeater's input receive connector ( i.e. the BNC on the Ch 60 BPF ). For example if the OSD reads -
60dBm, then the actual rf input signal level is -78dBm. With no input signal, and a 50 ohm
termination on the input BPF, the receiver displays -89 to -90dBm.
RECEIVER SENSITIVITY: The repeater has been tested for sensitivity. The test
signal was a "Normal" ham DVB-T signal with following digital parameters: 441 MHz, 6 MHz BW,
1080P, H.264, 5.5 Mbps, QPSK, 8K FFT, 5/6 FEC, & 1/16 Guard.
Repeater Turn-On = -95 dBm (with s/n = 8dB)
note: some picture defects and possible relay chattering
Repeater Turn-Off = -96 dBm (with s/n = 7dB)
Repeater Solidly On = >-93dBm (with higher s/n) -- perfect picture & audio
TV Rptrs Rptr-137.doc ( 7/19/23, kh6htv) p. 10 of 12
Fig. 8 Detailed Block Diagram for Repeater
TV Rptrs Rptr-137.doc ( 7/19/23, kh6htv) p. 11 of 12
Fig. 9 Schematic Diagram for PTT-PA Control Circuit
TV Rptrs Rptr-137.doc ( 7/19/23, kh6htv) p. 12 of 12
W0BTV Details: Inputs: 23 cm Primary (CCARC co-ordinated) + 70 cm secondary
all digital using European Broadcast TV standard, DVB-T 1243 MHz/6 MHz BW (primary),
plus 439 MHz/6 MHz BW and 439 MHz/2 MHz BW
Outputs: 70 cm Primary (CCARC co-ordinated), Channel 57 -- 423 MHz/6 MHz BW, DVB-T
Also, secondary analog, NTSC, FM-TV output on 5.905 GHz (24/7 microwave beacon).
Operational details in AN-51c Technical details in AN-53c. Available at:
W0BTV ATV Net: We hold a social ATV net on Thursday afternoon at 3 pm local
Mountain time (22:00 UTC). The net typically runs for 1 to 1 1/2 hours. A DVD ham travelogue is
usually played for about one hour before and 1/2 hour after the formal net. ATV nets are streamed live
using the British Amateur TV Club's server, via: Select ab0my or n0ye. We
use the Boulder ARES (BCARES) 2 meter FM voice repeater for intercom. 146.760 MHz ( -600 kHz,
100 Hz PL tone required to access).
Newsletter Details: This is a free newsletter distributed electronically via e-mail to
ATV hams. The distribution list has now grown to over 500+. News and articles from other ATV
groups are welcomed. Permission is granted to re-distribute it and also to re-print articles, as long as
you acknowledge the source. All past issues are archived at:
Free advertising space is offered here to ATV hams, ham clubs
or ARES groups. List here amateur radio & TV gear For Sale -
or - Want to Buy.
WANTED: Need a working Scientific Atlanta model 9270 modulator
for a repeater I am refurbishing. --- Buford Eastep, W4HVW Contact: or text 956-245-9625. ... tr-137.pdf
Prispevkov: 1012
Pridružen: 28 Okt 2004, 21:07

Re: revija ATV

OdgovorNapisal/-a s58ru » 02 Avg 2023, 07:16

TV Rptrs Rptr-138.doc ( 7/31/23, kh6htv) p. 1 of 10
Boulder Amateur
Television Club
TV Repeater's
August, 2023
issue #138
BATVC web site:
ATN web site:
Jim Andrews, KH6HTV, editor -
Burt, N7CS
Bob, K9PQ
WWATS give talk on ATV to Micro-Hams
On July 18th, the Western Washington Amateur Television Society (WWATS) gave a talk on
ATV/DATV to members of the MicroSoft ham club, Micro-HAMS. Both groups serve the amateur
community in the Puget Sound area (Seattle). Bob Helling, K9PQ and Burt Guillot, N7CS, gave the
presentation. It was complete with power-point slides, plus a live demo of several types of ATV gear,
including the new Icom IC-905 microwave transceiver. The program covered: Who and What is
WWATS, a high level overview of Analog and Digital Modes, the current state of the WWATS-ATV
repeater and activity, a little more in-depth talk on Digital Mode Options and Trade-Offs, analog FM
(Icom IC-905), a demonstration of both Analog and Digital Hardware - point to point ATV
TV Rptrs Rptr-138.doc ( 7/31/23, kh6htv) p. 2 of 10
Bob Helling, K9PQ, is the president of WWATS. He has been a ham since 1985 and is a lifetime
member of ARRL. He has operated primarily in EmComm for Seattle ACS and ATV for the last 20
Burt Guillot (N7CS) has been an amateur extra radio operator since 2019, and is a lifetime member of
the ARRL, AMSAT, and the Snohomish County Hams Club. He is a Board Member for the Western
Washington Amateur Television Society (WWATS), an ARRL VE, and member of Snohomish County
ACS and Marysville ACS. Burt is currently retired (Amazon).
To find out more about WWATS, check out their web site, They host an
analog, AM-TV, NTSC repeater with input of 434 MHz and output on 1253.25 MHz which transmits
from a commercial broadcast site on Couger mountain with good coverage of the greater Seattle area.
To find out more about Micro-Hams, check out their web site, and also
their You-Tube site, ... fJA/videos
EG5-DATV Story of a Journey (and more ! )
Lorenzo, IU1BOT
It all began with an idea from Philip, IZ5TEP who said to me, "What do we do, go to Spain for the
contest?" Now yo must know that Philip often jokes but that time the tone was different, he was
really convinced to leave and go to Spain for all the setups, from 29 MHz up to 10 GHz and what better
people to ask than Raf, IW1QEF, and yours truly.
So between one evaluation and another we chose the option that would later actually turn out to be the
final one. Raf's famous camper, all loaded and decked out for the big event ! Months of preparation
followed including the ferry to be taken to Civitavecchia, the equipment to be brought (strictly
redundant) and all the logistics regarding campers and people present. The initial idea was to involve
TV Rptrs Rptr-138.doc ( 7/31/23, kh6htv) p. 3 of 10
Carlotta, my "25", who then unfortunately due to work commitments could not come and so we put our
knowledge to good use..... and taaac! We are reminded of Francesco, IT9HZM, who immediately
accepted our invitation to participate in this all-crazy ATV DX-pedition.
Days pass and the fateful departure date arrives, good Raf, IW1QEF, retrieves his camper in the the
Chiavarese hinterland and picks me up in the company of Francesco, HZM. All together we head to
Viareggio to pick up Filippo and to load all the rest of the equipment. We had already sniffed
something, but arriving at TEP's place we find ourselves in front of a setup to be the envy of the biggest
EME operators. Hi ! Once everything is loaded, we move towards Civitavecchia to catch our ferry.
The ship trip goes by quite fast and we are always more impatient to start transmitting. We arrive at
7pm at the port of Barcelona and we immediately find a fellow amateur radio-catalanat waiting for us.
The legendary, Benjamin, EA3XU, whom we will never stop thanking for the incredible welcome.
After the usual greetings, we head to the resturant where we meet the president of the section URE
( Union of Spanish Radio Amateurs ), Barcelona section, Ricard, EA3IAO. After a wonderful
Catalan-style dinner, we all say our goodbyes and take our leave. We are ready to spend the first night
in the RV and leave the next day for Alicane, our first real purely radiant stop. On the way, at the
height of Benidorm, we get a call from our dearest Luis, EA5DOM, with whom we eat the inevitable
Paella. Meanwhile we plan the next activities. Also with him, we say goodbye with the certainty of
seeing each other later in one of our next spots.
WE arrive at Urbanova beach ( south Alicante ) and immediately start setting up everthing we need.
Surprise of surprises ! On 23cm band at 1296 MHz, we listen to IT9CIT's beacon in Alcamo, TP, from
sea level !
All rejoicing, we waited for the team of Sicilian friends to arrive at the post in Capo Vaticano, but
unfortunately when everything was ready the propagation was then too weak and we could not see each
other on DATV. We only managed to listen to the above beacon, so we leave a little sad.
The next day, after making about 20 contacts on 14 MHz, we reactivate our microwaves, but
unfortunately also that day the tropo was not on our side. So we decide to disassemble everything and
move to the next spot. It is Cumbre Del Sol at 350 mslm, overlooking the sea.
Once we get to the summit, we get another very welcome visit from Pasqual, EA5CLH, another
microwave friend who honors us with excellent wine and spens the whole afternoon with us. He
helped setting up antennas and making QSOs. At the same time, we manage to connect on 10 GHz
SSB, with our friend Luis, DOM, who is about 60 km away. After a disappointing afternoon, from the
radiation point of view, we say goodbye to Pasqual and get ready for dinner, at which time Luis,
EA5DOM, returns with more wine. ( Well, you can't help by thank them ! ) After an evening of
technical conversations and banter, I decide around 11pm local time to turn on the radio on 28 MHz.
We used the 3 element yagi which we used for DATV on 29 MHz aimed at Central America and
SURPRISE ! New Zealand long way away on SSB via the Caribbean ! OK, it was not the intent of
the expedition, however it was a nice contact anyway.
TV Rptrs Rptr-138.doc ( 7/31/23, kh6htv) p. 4 of 10
The next day, completely wiped
out from the three days on the
road, we decide to finally head to
the campsite for some well
deserved rest. Obviously we
don't make it to the parking lot in
time that we have already hoisted
the 13 element yagi for 70 cm,
obviously in the middle of the
campsite ! After ar relaxing
afternoon/evening, we leave for
bed. The next day, we set off for
Coll De Rats, a 900 mslm
mountain that should give us a
glimmer of possibility for the
Barcelona area, almost 400 km
Usual practice: we arrive, assemble, test and thanks to the teamwork. IZ5TEP at the RF part.
IU1BOT (me) at scheduling and keeping Italia contacts on SSB. IT9HZM at OBS video software.
IW1QEF at general logistics. We managed to pull out some unidirectional contacts on the 70 cm
DATV band with EA3XU, EA3IGB, EB3FYO and EA3UM for a total of about 1600 km. A meager
consolation, but still a great victory to have managed to pull something off despite the propagation that
practically existed in those days !
Back at the camsite, we began to assemble everything to do our live broadcast on NET Italy on QO100
which now takes place every Monday. This time, however, we broadcast practically only us because
the things to be said were really a lot. (You can see on YouTube by searching EG5DATV)
The following days passed in rest in anticipation of our journey back to Barcelona where the trusty
Benjamin, EA3XU, took us to the Barceloneta and the beach before catching the ferry back to
The bottom line is that despite the propagation not being on our side on this trip, it still allowed us to
pull out interesting contacts on various bands. But, most importantly, to get to know and touch the
incredible team of microwave enthusiasts in Spain. We were abolutely honored to have been
welcomed so warly by our collegues in Spanish zones 3 and 5.
A dear 73 to all, from me and the entire EG5DATV team ( IW1QEF, IZ5TEP, IT9HZM ) - until the
next DX-DATV-expedition which will probably be sooner than you think ! ! !
Lorenzo "Vash" Gianlorenzi, IU1BOT, Chiavari, Italia
TV Rptrs Rptr-138.doc ( 7/31/23, kh6htv) p. 5 of 10
WB5PJB's view from Daniel's Park, south of Denver
Boulder, Colorado, 5.8 GHz,
FM-TV, DX-Pedition
On Saturday, Don Nelson, N0YE, organized our
first summer 2023, microwave ATV DX-pedition.
He picked using the 5.8 GHz, 5 cm band using FMTV
as the most number of members have that
equipment. The following members participated:
Don, N0YE; Gary, WB5PJB; Lou, K0ANS;
Chris, K0CJG; Bill, AB0MY; Pete, WB2DVS;
Debbie, WB2DVT; & Ed, K0JOY. All went to
seperate, known good microwave locations, widely
spaced apart. Pete & Debbie operated from Ed's
ideal mountain top QTH with Ed. All were within
Boulder County with the exception of Gary. Gary
lives in Castle Rock, south of Denver. He operated Pete & Debbie posing for the camera
from a nearby county park with a great view north as seen in the above photo. The most distant ATV
QSO was between Gary and Lou at Rabbit mountain county park, north-west of Longmont. That
distance was 88.4 km (54.9 miles). Gary's closest contact was still at 32 miles with Don. Don was
set up west of Broomfield on CO-128 highway and McCaslin Blvd. Bill was at Legionaire's Hill.
Chris was at NCAR.
TV Rptrs Rptr-138.doc ( 7/31/23, kh6htv) p. 6 of 10
Prior to the outing, Jim, KH6HTV, had prepared a
detailed set of spread sheets with info about 20
possible microwave sites to be used. Site details
included: latitude/longitude, address, elevation,
access info, safety comments, etc. One table
gave distances to all other sites. Another table gave
compass bearings to all other sites. The last table
gave Radio Mobile rf path predictions of
anticipated signal strengths between all sites. For
the rf path predictions, we used our typical station
Pete & Debbie as seen by Gary, 76 km distance
parameters of 5.685 GHz, 600 mW transmitter, +22 dBi dish antennas mounted on tripods at 5 ft.
elevation, 0dB coax loss (assumed transmitter/receiver mounted directly to the dish antenna), and
required signal strength of > -100dBm (P0-P1 picture). Every site could see several other sites, but
no site was situated where it could see all sites. The distances between the various sites used on
Saturday ranged from 8 km to 88 km.
WB5PJB at Daniel's Park N0YE at CO-128
K0CJG at NCAR AB0MY at Legionaire's Hill
TV Rptrs Rptr-138.doc ( 7/31/23, kh6htv) p. 7 of 10
Everyone reported good reception of P4 to P5 pictures from most sites and no signal at all from sites
that were predicted to be "No Go". Everyone took photos of their video monitor screens, but most
photos submitted were of poor quality due to the intense sun glare even when they tried to use sun
Most used the popular combo of the TS832 transmitter and RC832 receiver sold by Amazon for a low
$30. We have reported on these in previous issues of this newsletter. Some also used a 2 Watt, afterburner
amplifier. The most common dish antenna used was the BBQ grill from L-Com, model
HG4988-22EG. It has +22dBi gain. Don used two antennas, one for transmitt and one for receive.
One was the L-Com, the other was a RadioWave model SP1-2/5, 0.3m, dual-band 2.4/5.8GHz. It has
+23dBi gain on 5cm. Chris used a hand-me-down from Don which was a surplus dish with a homebrew
feed. Gain = ? Gary had the highest gain antenna at +30dBi. He was using a Ubiquiti model
RD5G30 It is called the airMAX Rocket Dish and had dual polarity feeds. It is 26" diameter. Rated
for 5.1 to 5.9GHz at 30dBi with 5.8 degree (-3dB) beamwidth. (note: it is currently selling for $109)
Now Don is posing the question --- "What do we do for an encore? What band and what mode
next ?"
K0DGS Publishes in Microwave Journal
Our local, Boulder, Colorado, Filter Expert -- Dan Swanson, K0DGS, just had an
invited paper published in the famous magazine, MICROWAVE JOURNAL ( ).
It appeared in the most recent, July, 2023 issue on pages 58-68. Dan's article was entitled "The
Impact of Topology and Parasitics on SMT Bandpass Filters." Dan shows how filters for the low
GHz region can still be fabricated on pc boards using surface mount, discrete, L & C components.
The thrust of Dan's article is for your filter design to be successful, you need to take into account the
parasitic elements associated with each SMT component, plus model the pc pads and interconnects as
transmission line elements. The example shown above from Dan's article is a 1 GHz Band-Pass Filter.
Dan has worked in the microwave industry now for over 40 years. He is a Fellow of the IEEE. He
currently works as an independent consultant and teaches short course classes in filter design. His web
TV Rptrs Rptr-138.doc ( 7/31/23, kh6htv) p. 8 of 10
site is: ( ) Dan's main ham radio interest is HF with his new Icom IC-7300 and
a 40-10m, end-feed wire antenna with which he works the world. His ATV connection is having a
bunch of ATV ham radio friends who he sees weekly along with many other hams for a local ham
breakfast. Plus, Dan designed for us a really great 23 cm band-pass, band-notch filter for our W0BTVATV
repeater. We desperately needed it to eliminate a very strong, in-band, FAA radar signal. We
have written about Dan and this filter previously back in 2018 & 2020 in newsletter issues #6 & 32.
In a follow-on discussion in person with Dan at our weekly ham breakfast, I said that Dan's designs in
the article still required some very accurate values of small value SMD capacitors and inductors. The
conventional SMD inductors and capacitors that I purchase at places like Mouser and Digi-Key don't
offer that kind of resolution. In particular I found it impossible to find any less than 1pF, except for a
0.5pF chip, and then with very loose tolerances. Dan said that he used SMD, thin film capacitors in
the Accu-P series from Kyocera/AVX which were available in 0.05pF steps from 0.05pF up to 2pF, and
0.1pf steps then up to 4.7pF. They offer tolerances as tight as a phenomenal ±0.01pF. For inductors,
he used Coilcraft which offered 0402 wirewound chip values from 2.8nH to 10nH in 0.1nH steps. Dan
also said that for anything less than 1 or 2nH, he instead uses a printed line.
1920's era Mobile Ham Radio -- also good
for hanging up the wash to dry !
ARRL Breaking News ! The ARRL has just announced that
effective the first of January, dues will be increased dramatically. Currently the annual dues are
$49/year which includes a subscription for QST magazine. On January first, the dues will go up $10
to $59/year, BUT they will no longer include receiving a hard copy of QST in the mail. For $59, it
will only be available on-line. If one stills want to receive the hard copy in the mail, the dues will be
an extra $25, or $84 total/year. Thus the dues increase is really an additional $35/year.
W0BTV Details: Inputs: 23 cm Primary (CCARC co-ordinated) + 70 cm secondary
all digital using European Broadcast TV standard, DVB-T 23cm, 1243 MHz/6 MHz BW
(primary), plus 70cm (secondary) on 439 MHz with 2 receivers of 6 & 2 MHz BW
Outputs: 70 cm Primary (CCARC co-ordinated), Channel 57 -- 423 MHz/6 MHz BW, DVB-T
Also, secondary analog, NTSC, FM-TV output on 5.905 GHz (24/7 microwave beacon).
TV Rptrs Rptr-138.doc ( 7/31/23, kh6htv) p. 9 of 10
Operational details in AN-51c Technical details in AN-53c. Available at:
W0BTV ATV Net: We hold a social ATV net on Thursday afternoon at 3 pm local
Mountain time (22:00 UTC). The net typically runs for 1 to 1 1/2 hours. A DVD ham travelogue is
usually played for about one hour before and 1/2 hour after the formal net. ATV nets are streamed live
using the British Amateur TV Club's server, via: Select ab0my or n0ye. We
use the Boulder ARES (BCARES) 2 meter FM voice repeater for intercom. 146.760 MHz ( -600 kHz,
100 Hz PL tone required to access).
Newsletter Details: This is a free newsletter distributed electronically via e-mail to
ATV hams. The distribution list has now grown to over 500+. News and articles from other ATV
groups are welcomed. Permission is granted to re-distribute it and also to re-print articles, as long as
you acknowledge the source. All past issues are archived at:
Newsletter Success Story: We started this ATV newsletter in July, 2018
as the "Boulder TV Repeater's Repeater". At the time, it was strictly a local newsletter for the small
handful of dedicated ATV hams in Boulder, Colorado. The original intent was to do a monthly
newsletter. For a newsletter editor, success is when you no longer need to scratch around and write
all the material yourself, but your readers start supplying you with material. Well, this newsletter has
now grown to become the "de-facto", free, USA, ATV newsletter with over 500+ ATV ham readers.
(??? in the USA, plus ??? overseas). These readers are now supplying news of their ATV group's local
events and interesting technical, or operational articles.
So why are you receiving this newsletter so often, rather than just monthly ? My policy is if the
newsletter becomes too big ( I receive one exchange ham newsletter with typically 125 pages of small
print), that the reader will be intimidated and set it aside to maybe (often not) read it later. Thus, I
limit the size of this newsletter to about a dozen pages in 12 point type, with lots of photos. I hope this
makes for a quick, enjoyable read as soon as you receive it in your email in-basket. After finishing
one newsletter, I immediately start on the next one, as available material comes in. When I reach the
≈12 page limit -- then time to send it out via e-mail. Thus, for July, 2023 (5th year) , we ended up
with four editions, essentially on a weekly basis.
Thank you to all our ATV readers. An especially Big Thank You to those of you who are submitting
material to share with other fellow ATV hams.
Jim, KH6HTV, Editor
TV Rptrs Rptr-138.doc ( 7/31/23, kh6htv) p. 10 of 10
Free advertising space is offered here to ATV hams, ham clubs
or ARES groups. List here amateur radio & TV gear For Sale -
or - Want to Buy. ... tr-138.pdf
Prispevkov: 1012
Pridružen: 28 Okt 2004, 21:07

Re: revija ATV

OdgovorNapisal/-a s58ru » 11 Avg 2023, 21:19

TV Rptrs Rptr-139.doc ( 8/11/23, kh6htv) p. 1 of 10
Boulder Amateur
Television Club
TV Repeater's
August, 2023
2ed edition, issue #139
BATVC web site:
ATN web site:
Jim Andrews, KH6HTV, editor -
News from Japan --
358 km, 5.7 GHz, DATV Success !
Fumio Sekizaki, JA0RUZ
TV Rptrs Rptr-139.doc ( 8/11/23, kh6htv) p. 2 of 10
On July 29th and 30th, I started the Nihonkai Duct
DX Challenge with the JA0GPO station in Nagano
at 7 o'clock and went to the vicinity of Meotoiwa
Rock in Shika Town on the Noto Peninsula and Mt.
The communication partner station is a JA4JKE
station moving near Takohana, Matsue City,
Shimane Prefecture, near Tenku no Misaki, and the
main purpose is 5.7GHz and 10.2GHz FM and
FHD-ATV (ISDB-T) communication.
According to the forecast for the Sea of Japan duct on this day, the conditions were not very good, but
the schedules of both sides matched, so we decided to go ahead with this day.
On the 29th, try the approximately 366km between Takohana, Matsue City, Shimane Prefecture and
Shika Town, Ishikawa Prefecture! In FM, he receives a strong signal of about 59 + 60dB (reading the S
meter of IC-1275 with TRV connection), but it is impossible to make a video with such a thing. He
can't see the ISDB-T image unless it's 30-40dB stronger! ! We tried for several hours, but could not
reach full high-definition image communication.
After that, he joined the JA9BPH station at the
nearby "Ganmon Cliff Park" from the morning, and
after joining the JA9BPH station, he was advised
by a certain local government official that "a good
point with a good view for wireless operation".
Disbanded after previewing. (However, the
direction of the opening is bad!) When you are
doing something unfamiliar to you near the
coastline, you will see most of the civil servants.
I got it!
This kind of thing happens quite often, so I will
use Novolibata to make it visible even from a
distance, saying, "Amateur radio station radio wave
propagation experiments in progress"!
TV Rptrs Rptr-139.doc ( 8/11/23, kh6htv) p. 3 of 10
On the next day, the 30th, we changed our schedule and headed to Mt. Houdatsu, this time about
358km, and tried again. The difference in distance has almost no effect, but I thought that the heat
would be different because it would be a little higher. Mt. Houdatsu was under construction in various
places, so I set it up at the entrance of Mt. A signal came in, so I hurriedly replaced the FHD-ATV,
and surprisingly the video signal could be decoded. After a while and fine-tuning the beam, a full
high-definition image was projected! ! !
This was a distance that I had never tried before, but the JA0GPO station was also able to succeed in
"two-way communication with 5.7GHz FHD-ATV with a span of 358km" at the same time.
See "evidence video" on You-Tube.
TV Rptrs Rptr-139.doc ( 8/11/23, kh6htv) p. 4 of 10
I think this is probably the first time in the world that this full high-definition ATV has successfully
communicated over a 358 km non-line-of-sight span ! !
We 64QAM RF output at 5.7GHz was about 0.3W~0.6W, and he used a 60cm~100cm parabola and
was able to communicate in two-way.
This is the longest distance even in Japan, but I'm curious about the world record for Full-HD ATV
(1920 x 1080 30fps) ?
In addition, we communicated with a 430 MHz, 20 Watt, 10-element Yagi antenna, but this time it was
not FS with 430 M, and it was operated under conditions that could not be said to be a strong duct, but
5.7 GHz is very strong. It has been successful at times.
In other words, the propagation of V/U in the Sea of Japan duct can only be used as a reference, and we
have come to understand that "microwave propagation cannot be understood unless you try it!"
However , it would be a waste to not use such a wonderful propagation band because of "wrong
subconsciousness" .  After all, the mobile operation this time was a “fight against the heat wave”, and
it was operated in a situation where both people and equipment were considerably down during the
preparation stage, and even smartphones could not work properly . FHD-ATV video transmission and
reception equipment and other troubles have come out many times! ! In addition, 10.2GHz did not
improve the duct condition, so I gave up with only FS of FM this time.
However, the Sea of Japan Duct is addictive! ! !
73 de Fumio, JA0RUZ, Email:
Another 70 cm Mid-West
Band Opening for DATV
Another ATV band 70cm opening this morning (5 August
2023). Pictured is William’s (WB8YIF) DVBT receiver
monitor located in Little Hocking, Ohio, during reception
of (W8URI) Bill’s ATV signal. W8URI is located in Mt
Gilead Ohio, a 109 mile path.
Cheers, Dave, AH2AR
TV Rptrs Rptr-139.doc ( 8/11/23, kh6htv) p. 5 of 10
Boulder, Colorado BATVC
& W0BTV-ATV Repeater
We have still been struggling with the issue of poor
sensitivity of the 70cm receivers on the W0BTV, DATV
repeater. This is after our exciting report in the recent July
16th newsletter (issue #136) that our RFI had disappeared.
Unforutnately, we now need to report it has returned.
Plus, now another serious issue has arisen. Something has
failed in our remote control, radio circuit. We use a 2
meter FM radio with touch-tones (DTMF) to control
various functions, plus the FCC requirement to remotely
disable the repeater in the event of a mal-function. Also,
the 5.9 GHz, FM-TV beacon had again failed.
So, trustees, Don, N0YE, & Jim, KH6HTV, once again
made a trip to the repeater site. As always, we needed to
call in advance and make an appointment for access. This
time, we asked for a 2 hour time slot to make a bunch of
spectrum analyzer measurements on the 70 cm band, plus do other trouble shooting and climb on the
roof to remove the 5.9 GHz transmitter. As it turned out, 2 hours was not nearly enough time, we
stretched it to 3 hours, pushing the limits of our welcome. Even then we didn't finish all the
experiments and measurements we wanted to do. We did find that the DTMF decoder was receiving
the proper tones, but was not responding to them. The DC power to the remote, roof top mounted, 5.9
GHz transmitter was not working. At the end of the session, we removed both the main repeater rack
and the 5.9 GHz transmitter box and they are now resting in Jim's ham shack for repairs.
We did learn quite a bit more about our poor 70cm receiver sensitivity problem using our Rigol DSA-
815 spectrum analyzer. We measured signals directly from the repeater's Diamond, X-6000, tri-band
(2m/70cm/23cm) antenna. We also measured the signals later internal to the repeater's receiver at the
output of the 3dB signal splitter, just before it went to the Hi-Des DVB-T receivers. At this point the
antenna signals had gone through the input circuits of the triplexer, 70cm - 6 MHz band-pass filter, low
noise pre-amp and 3dB power splitter. We captured lots of various screen images on a USB memory
stick for later study. The most relevant are shown here as Figs 1-3 on the following pages. The
same settings were used for all three figures. They were the same as recommended by ITU for
measuring DVB-T signals. Center Freq = 439 MHz, Span = 20MHz (i.e. 2 MHz/div). Vertical
settings were: 10dB/div, 0dB input attenuation, LNA turned on, RMS detector, IF resolution
bandwidth = 30kHz, video bandwidth = 300kHz, sweep scan time = 2 seconds.
TV Rptrs Rptr-139.doc ( 8/11/23, kh6htv) p. 6 of 10
Fig. 1 Baseline Noise from Receive Antenna - with no DATV signal present at 439 MHz.
Yellow trace = "live" single sweep. Magenta trace = peak hold after 1 minute of sweeping. Other
ham signals were seen above 444MHz.
Fig. 2 A DVB-T, 439 MHz, 6 MHz BW signal from Jack, K0HEH --- marginal. Decoded
signal did have live motion with audio - But also suffered from intermittant freeze frames. Signal
measured inside the repeater at the output of the 70cm 3dB power splitter. Signal had passed through
TV Rptrs Rptr-139.doc ( 8/11/23, kh6htv) p. 7 of 10
the input circuits of triplexer, 6 MHz band-pass filter, low noise pre-amp and then the 3dB splitter.
Magenta (purple) trace is "live" single sweep taken at a time with RFI was minimum. Cyan (blue)
trace is peak hold after 2 minutes of sweeping. It captures both TV signal and the max. amount of RFI
Fig. 3 Same set-up as Fig. 2. Receive antenna is connected. This time no external DTV
signal present. But our own locally generated, weak DVB-T test signal is inserted via directional
For Fig. 3, the test signal was set at digital threshold of the repeater's receiver. Magenta (purple) trace
was just the test DVB-T signal without the receive antenna attached. A 50Ω termination was
substitued for the antenna. This trace was then "frozen". Then the antenna was attached to the
directional coupler and the repeater receiver for the remaining two traces. The test signal was still
being injected. There were no other DTV signals on the air at this same test time. The yellow trace is
a "live" single sweep. The cyan (blue) trace is the same, but in the peak hold mode for about 2
minutes of sweeps. The spikes seen at 445.5MHz in both Figs. 2 & 3 was some other ham's signals
or voice repeaters.
So What Do These Tests Tell Us ?
#1 Our repeater is in a very noisy environment with way too much very broad band, RFI, noise
#2 The noise is always there, but bursts sometimes 15dB higher and recurs quite often, every few
TV Rptrs Rptr-139.doc ( 8/11/23, kh6htv) p. 8 of 10
#3 Nothing we can do with further band-pass filtering, etc. will cure the problem. Our problem
is the external EM environment at our repeater site.
Let's analyze Fig. 1 further. First the spectrum analyzer background noise level is much less than
shown here. With the same identical setup at KH6HTV's QTH in a residental area and an outdoor
yagi antenna attached to the analyzer, the baseline noise seen is of the order of -112dBm. The yellow
trace in Fig. 1 is showing a min. level of about -100dBm. Easily 10-12dB worse. If you look
carefully on the yellow trace at 433-434MHz, you will see some higher level RFI moving across the
sweep with peaks up to almost -90dBm. Now look at the magenta trace for the peak hold of anything
which occured over a minute time frame. We now see RFI peaks reaching as high as about -82dBm.
Easily 20dB higher than seen in a quiet RFI environment.
Figs. 2 & 3 taken inside the repeater vividly demonstrate that our band-pass filter and preamp are
working and working quite well. They have wiped out most everything else out which is outside of
the BPF's passband, plus amplified the in-band signals properly.
Fig. 3 demonstrates the impact of external RFI upon our ability to receive weak DVB-T, 70cm signals.
When the antenna was removed and replaced with a 50Ω termination, the level of the DVB-T test
signal was then adjusted with a step attenuator. More and more attenuation was cranked in until the
digital threshold was reached. This was at the point where the received picture was still P5 with Q5
audio. Adding 1 more dB beyond this point caused freeze framing. The attenuator settings were
then recorded. This then showed the basic sensitivity of the repeater's 439/6 MHz receiver was
approxiamately -89dBm. That spectrum level was then "frozen" on the Rigol's screen as the magenta
trace seen in Fig. 3. The 50Ω termination was then removed and the repeater's outside antenna was
once again connected to the repeater. The yellow and cyan traces now show the effects of adding the
outside world RFI. The yellow trace is a "live" single sweep, while the cyan trace was the peak hold.
Now the receiver would no longer decode the test DVB-T signal. We then proceeded to reduce the
step attenuator settings and note what happened to our decoded TV picture. With stronger test signals,
we started to get some motion and audio but with intermittant freeze framing. When the test signal
was finally about -63dBm, we were finally able to get above the level of the RFI and once again see
perfect P5 pictures with Q5 audio. This -63dBm number correlated quite well with in the field
measurements we had preformed during previous ATV nets. They too had showed that a very strong
signal into the repeater was required for good performance, free from freeze-framing.
So, now what do we do ? --- This is a discussion --- to be continued.
73 de Jim, KH6HTV, & Don, N0YE, --- W0BTV Trustees
TV Rptrs Rptr-139.doc ( 8/11/23, kh6htv) p. 9 of 10
W0BTV Details: Inputs: 23 cm Primary (CCARC co-ordinated) + 70 cm secondary
all digital using European Broadcast TV standard, DVB-T 23cm, 1243 MHz/6 MHz BW
(primary), plus 70cm (secondary) on 439 MHz with 2 receivers of 6 & 2 MHz BW
Outputs: 70 cm Primary (CCARC co-ordinated), Channel 57 -- 423 MHz/6 MHz BW, DVB-T
Also, secondary analog, NTSC, FM-TV output on 5.905 GHz (24/7 microwave beacon).
Operational details in AN-51c Technical details in AN-53c. Available at:
W0BTV ATV Net: We hold a social ATV net on Thursday afternoon at 3 pm local
Mountain time (22:00 UTC). The net typically runs for 1 to 1 1/2 hours. A DVD ham travelogue is
usually played for about one hour before and 1/2 hour after the formal net. ATV nets are streamed live
using the British Amateur TV Club's server, via: Select ab0my or n0ye. We
use the Boulder ARES (BCARES) 2 meter FM voice repeater for intercom. 146.760 MHz ( -600 kHz,
100 Hz PL tone required to access).
Newsletter Details: This is a free newsletter distributed electronically via e-mail to
ATV hams. The distribution list has now grown to over 500+. News and articles from other ATV
groups are welcomed. Permission is granted to re-distribute it and also to re-print articles, as long as
you acknowledge the source. All past issues are archived at:
Free advertising space is offered here to ATV hams, ham clubs
or ARES groups. List here amateur radio & TV gear For Sale -
or - Want to Buy.
Disclaimer: This just came in the mail. I do not know anything about this
company. But if you have a ham radio estate to dispose of, it would be
worth checking out. - kh6htv
TV Rptrs Rptr-139.doc ( 8/11/23, kh6htv) p. 10 of 10 ... tr-139.pdf
Prispevkov: 1012
Pridružen: 28 Okt 2004, 21:07

Re: revija ATV

OdgovorNapisal/-a s58ru » 01 Sep 2023, 18:58

TV Rptrs Rptr-140.doc ( 8/31/23, kh6htv) p. 1 of 8
Boulder Amateur
Television Club
TV Repeater's
September, 2023
issue #140
BATVC web site:
ATN web site:
Jim Andrews, KH6HTV, editor -
Boltzmann Constant -- Thermal Noise
The latest September issue of QST has an excellant article in it by Adrian Ryan, 5B4AIY. It is entitled
"Understanding the Boltzman Constant". He describes what it is and how we hams can use it to
understand the fundamental laws of physics which determine the ultimate sensitivity of our receivers.
He also discusses the origin and definition of "S" units. Definitely recommended reading.
The basic equation to describe thermal noise power, Pt, is: Pt = k * T * B
where k is the Boltzman constant = 1.380649 x 10-23 Joules/degree Kelvin
T is the absolute Temperature measured in degrees Kelvin (room temperature = 290o K)
and B is the Band-Width measured in Hertz
To make this equation easy to use, check out the on-line calculator tool at: ... calculator
Ryan works through some typical ham radio bandwidths for CW and SSB and then expresses the
results in dBm. The thermal noise floor is thus:
1 Hz => -174dBm, 500 Hz (CW) => -147 dBm, 2.4 kHz (SSB) => -140 dBm
He further states that the typical amateur operator needs about 10dB s/n to copy reliably. Thus these
numbers come up 10 dB to -137 dBm (500 Hz) & -130 dBm (2.4 kHz).
Then with a noisy front-end receiver, the receiver's noise figure (NF in dB) needs to also be added to
these numbers. He gives an example of a typical HF receiver (IC-7610) with a noise figure of 9dB,
the resultant numbers are now up to -128dBm (500 Hz) & -121dBm (2.4 kHz).
TV Rptrs Rptr-140.doc ( 8/31/23, kh6htv) p. 2 of 8
So what is the impact for us ATV hams ? For ATV, we use much wider band-widths than the typical
HF ham on CW or SSB. Using these examples and going to higher band-widths should give you an
appreciation of the smallest signal you can expect to receive with your ATV gear. Let's start with our
typical 6 MHz wide TV channel. Now using the above equation our residual thermal noise floor is
a really big number of -106dBm ! This is just the noise floor, it doesn't account for the required S/N
of our video detector, nor the front-end noise figure of our receiver. They only make it worse. .
So how does this compare with some real world measurements? I have made lots of sensitivity
measurements over the years of various digital (DVB-T) receivers. For what I considered my
standardized digital parameters (H.264 encoding, 1080P, 5.5Mbps - 6MHz BW, QPSK, 8K FFT, 5/6
Code Rate (FEC) & 1/16 Guard), I almost always ended up measuring a receiver sensitivity of about -
94 or -95dBm. Then adding a good low noise (< 1dB NF) pre-amp, these numbers improved to about
-99dBm. When performing these tests on a Hi-Des receiver which includes a built-in accurate dBm S
meter and S/N meter, the digital threshold always came out at about 8dB S/N.
So what does that tell me. -99dBm (sens) - 8dB (s/n) ==> -107dBm
Whow! -- that number comes damm close to the computed -106dBm for 6 MHz thermal noise ! So
we must be in the ball park with our measurements and calculations.
So what can we do to improve on this -99dBm value ? For starters, we can use more aggessive
forward error correction encoding. I have found going to 1/2 FEC lowers the required S/N from 8 to
5dB. Remember to also lower the video encoding rate accordingly. Plus we can go to a lower bandwidth.
If we go to a typical narrower band-width of 2 MHz, this improves the theoretical noise level
a bit from -106dBm to -111dBm.
73 de Jim, KH6HTV, Boulder, Colorado
W0BTV - ATV Repeater Status Update:
Our regular Boulder ATV repeater, W0BTV, is presently out of service. It is in KH6HTV's ham shack
for repair and modification. The control receiver's touch tone decoder has been repaired. The 5.9
GHz, FM-TV transmitter is again functioning. Don, N0YE, is modifying the Arduino's firmware to
correct some issues, including audio routing. A new 7", hi-res, flat screen monitor has been added to
replace the 10+ year old Haier, low-res (240 line) monitor. Based upon Colin's (WA2YUN) spectrum
observations and recommendations, we will be moving the input frequency of the 70cm receivers back
to the original 441 MHz. We had recently moved to 439 MHz in an unsuccessful attempt to get away
from the RFI. A new, 70cm, 2 MHz band-width, channel filter has been on order for quite some time
now from a ham radio store in Hong Kong. When it arrives it will be installed in front of the Hi-Des
HV-110, 441MHz, 2 MHz BW receiver. We hope it arrives soon. USPS tracking shows it has arrived
at US Customs in Los Angeles.
In the interium, we have installed the BCARES, portable, W0BCR, DVB-T repeater. It is strictly a
70cm in/out, in-band repeater. Our W0BTV is primarily a cross-band repeater with 23cm input and
70cm output. It also has a pair of secondary 70cm receivers for 6 MHz and 2 MHz band-widths.
TV Rptrs Rptr-140.doc ( 8/31/23, kh6htv) p. 3 of 8
However, due to the extremely high level of 70cm RFI at the site, the BCARES 70cm receivers have
very limited usefulness. The RFI is so strong that an incoming 70cm DVB-T signal needs to be
stronger than -60dBm to override the RFI. We are taking at least a 30dB hit in sensitivity. Thus,
currently only 2 or 3 members are able to access the repeater.
We were considering moving the W0BTV repeater to a different, quieter location. We had a good
mountain top site in mind, but were unable to gain access to it. We thus will continue to keep the
repeater at it's current location on the noisy mesa south-west of the city of Boulder. We will continue
to encourage all ATV users to only use the 23cm input (1243 MHz) and forget about the 70cm inputs.
The 23cm input is RFI free. We had the 70cm inputs on the repeater historically dating back to the
early 1990s. When the Boulder ATV repeater was first frequency coordinated with the CCARC in
early 90s, it was even then as a cross-band (23cm in / 70cm out) repeater. The 70cm inputs were put
there mainly to be able to support BCARES. All of the BCARES, ATV gear was then and is still now
on the 70cm band. In the next issue, we will discuss how we might implement some remote 70cm,
DVB-T receive sites for W0BTV to still be able to support BCARES.
73 de Jim, KH6HTV, trustee for W0BTV
11th Annual International ATV QSO Party
Peter Cossins, VK3BFG, once again organized and
moderated this ATV QSO party. Thanks to Mick, VK3CH,
editor of NEVARC-NEWS for this summary and the photos
of participants.
The annual Digital ATV QSO Party was scheduled for
Friday August 25 starting around 0930 UTC with mainly
VK stations with Saturday morning/afternoon on August 26
being our link with USA. It was their Friday night.
Stations acting as local Anchors were Bevan VK5BD in
Port Pirie, Gary VK2CRJ in Sydney, Art WA8RMC in
Columbus Ohio, Bill AB0MY in Boulder Colorado and
Roland KC6JPG in Los Angeles. Also participating this
year was Claudia, I2NDT, our first European participant for
quite a while.
Peter, VK3BFG
BATVC: This year the Boulder, Colorado ATVers didn't participate, except for Bill. This was
because our W0BTV, cross-band (23cm in / 70cm out) DVB-T repeater was out of service for repair
and modification. As described in the above article, only 2 or 3 members are presently able to key up
the temporary BCARES, 70cm portable repeater.
TV Rptrs Rptr-140.doc ( 8/31/23, kh6htv) p. 4 of 8
TV Rptrs Rptr-140.doc ( 8/31/23, kh6htv) p. 5 of 8
New Microwave Antenna Supplier
The latest, Sept. issue of QST had a small ad
on page 118 for microwave antennas for the
IC-905. I was unaware of this company
before and it was the first time they advertised
in QST. Technical Antennas
The ad featured two dish antennas with very broad frequency coverage, so I decided to at least check
out their web site. The dish shown here with 0.6-6.5 GHz coverage appears to be the classical BBQ
grill, grid parabolic dish we have seen for many years for 2.4 GHz, but with a different feed assembly.
The feed assembly looks to be a log-periodic antenna thus accounting for the broad frequency
coverage. The BBQ grill measures 24"x39". They are asking $189 for it. Amazon offers on it's
web site what appears to be the same antenna, with same specs., for $200 with two day prime shipping.
TV Rptrs Rptr-140.doc ( 8/31/23, kh6htv) p. 6 of 8
Their ad also featured an even larger 48" dia. circular mesh dish with coverage up to 10 GHz. They
are quite proud of it as they are asking $979 for it.
If anyone has any microwave experience with this company and these antennas, we would like to hear
from you and pass on your observations to our readers.
New 70cm, DVB-T receivers
Allen, K0ARK, EC (left) and Pete, WB2DVS,
Equipment Officer (right) at work installing the
new DVB-T receivers in the BCARES office at the
BCARES has New DVB-T Receivers
The Boulder County ARES (BCARES) emergency coordinator, Allen Bishop, K0ARK, has instituted a
new effort to enhance our ATV capability for serving the public safety agencies in Boulder County.
As a first step, he asked Jim, KH6HTV, to provide a quad set of 70cm DVB-T receivers. Previously,
BCARES only had the capability to receive and display a single ATV channel. The new receivers
were installed on August 29th in the BCARES office in the Boulder County Emergency Operations
Center (EOC). The BCARES office is immediately adjacent to the master Command & Control
situation room. The Boulder County 911 dispatch center is also located in the same building.
The new GT-Media receivers were programmed to receive all of the 6 MHz, 70cm, ATV channels.
Their 1080P hi-def HDMI outputs are then sent to an HDMI quad processor. The quad video output is
then routed to a large screen video monitor seen in the above photo. It is also piped directly into the
EOC building's video distribution network where it can be displayed on any other large screen monitor
throughout the building, including in the master situation room. Don, N0YE, provided a test signal
via the ATV repeater for initial testing as seen in the above photo.
TV Rptrs Rptr-140.doc ( 8/31/23, kh6htv) p. 7 of 8
The RF circuit starts with a Diamond model X-50 (2m/70cm) vertical antenna on the roof of the EOC.
In the BCARES office, the signal is then split with a Diamond 2m/70cm duplexer. The 2m signal goes
to a 2 meter packet radio. The 70cm signal goes first to a KH6HTV model 70-LNA, low noise, 20dB,
pre-amplifier. The output of the pre-amp is then split four ways with a Narda SMA power splitter (-
6dB loss). These four outputs then go to the four GT-Media receivers. All of the receivers and the
pre-amp are powered from a common +12Vdc power supply.
September, QST - Trivia: Their cover photo is a "hookey" posed group photo. It shows a group of
high school students gathered around a table with an HF ham rig. One student is holding the mike and
talking into it while another is tuning the radio. Everyone else is watching the "excitement". So
what is "hookey" about it ? No cables attached ! AC power cord is missing from the power supply.
Power supply not connected to the transceiver. No antenna coax connected to the rig. Obviously a
staged photo op.
W0BTV Details: Inputs: 23 cm Primary (CCARC co-ordinated) + 70 cm secondary
all digital using European Broadcast TV standard, DVB-T 23cm, 1243 MHz/6 MHz BW
(primary), plus 70cm (secondary) on 441 MHz with 2 receivers of 6 & 2 MHz BW
Outputs: 70 cm Primary (CCARC co-ordinated), Channel 57 -- 423 MHz/6 MHz BW, DVB-T
Also, secondary analog, NTSC, FM-TV output on 5.905 GHz (24/7 microwave beacon).
Operational details in AN-51c Technical details in AN-53c. Available at:
W0BTV ATV Net: We hold a social ATV net on Thursday afternoon at 3 pm local
Mountain time (22:00 UTC). The net typically runs for 1 to 1 1/2 hours. A DVD ham travelogue is
usually played for about one hour before and 1/2 hour after the formal net. ATV nets are streamed live
using the British Amateur TV Club's server, via: Select ab0my or n0ye. We
use the Boulder ARES (BCARES) 2 meter FM voice repeater for intercom. 146.760 MHz ( -600 kHz,
100 Hz PL tone required to access).
Newsletter Details: This is a free newsletter distributed electronically via e-mail to
ATV hams. The distribution list has now grown to over 500+. News and articles from other ATV
groups are welcomed. Permission is granted to re-distribute it and also to re-print articles, as long as
you acknowledge the source. All past issues are archived at:
Free advertising space is offered here to ATV hams, ham clubs
or ARES groups. List here amateur radio & TV gear For Sale -
or - Want to Buy.
TV Rptrs Rptr-140.doc ( 8/31/23, kh6htv) p. 8 of 8
KH6HTV VIDEO offers for sale a
consumer grade, digital TV receiver
which we have pre-programmed for
DVB-T operation on the amateur 70 &
33cm bands. Price is $50 + shipping.
For details -- see web site ... tr-140.pdf
Prispevkov: 1012
Pridružen: 28 Okt 2004, 21:07

Re: revija ATV

OdgovorNapisal/-a s58ru » 12 Sep 2023, 22:32

TV Rptrs Rptr-141.doc ( 9/12/23, kh6htv) p. 1 of 12
Boulder Amateur
Television Club
TV Repeater's
September, 2023
2ed edition, issue #141
BATVC web site:
ATN web site:
Jim Andrews, KH6HTV, editor -
Where Was ARES for the Maui Fires ?
An Editorial ---- Jim, KH6HTV, Boulder, Colorado
I may be wrong, but I feel that something serious was missing from the emergency response to the
recent, devasting Fire Storm which destroyed the entire town of Lahaina on the Island of Maui, in
Hawaii. What was it you say ? -- it was ARES ! Where were they when the "#^T@%R hit the fan"
??? The press releases sent out by the ARRL section manager, Joe, AH0A, and ARRL headquarters
simply talked platitudes. Only talking about the available amateur repeater network available on Maui
for use by later, after the fact, relief personel. No mention anywhere of ARES. Why? -- Because it
really didn't exist on Maui. It was there in name only, a paper organization. A paper tiger with no
You say, how can you a fella in Colorado point your finger at them? I speak from first hand
experience having lived on Maui. Note my KH6 call sign. Our son, Steve, lives and has worked on
Maui since 1995. After retiring in 2001, Janet and I became "snow-birds" living on the island of Maui
for six months every year. We owned a home there on the island. I was a member of the Maui
Amateur Radio Club ( KH6RS ) and attended regularly their meetings and also gave several technical
talks to the club. We really felt like residents of Maui, not tourists. We actually had a much larger
circle of friends on Maui, than we did in our original home of Boulder, Colorado. In 2019, we sold our
Maui home and left the island for good. Why? I had some serious medical issues and the deciding
factor was the lack of quality medical care on the island.
The ARRL prides itself to the general public as being a viable emergency communications service.
This is done via ARES. However, it is really up to the local radio amateurs to actually make ARES
TV Rptrs Rptr-141.doc ( 9/12/23, kh6htv) p. 2 of 12
work - or not. The national ARRL can't force it to work without the locals. It works in Boulder,
Colorado --- It didn't work on Maui.
I know from personal experience that ARES can be effective locally. My background in ARES dates
back almost 50 years to the founding in Boulder, Colorado of our local ARES group, BCARES
(Boulder County Amateur Radio Emergency Services). BCARES became a real organization with
lots of active members, required member approval from the Sheriff, actual meetings and training
sessions, field exercises --- and most importantly -- We actually were called upon (via Sheriff's pager)
to respond to real bonafied emergencies. When we were called, we came. We actually have an
office of our own in the county emergency operations center (EOC) and a storage cache there for a lot
of specialized communication equipment with 24/7 access. Plus a 2 meter repeater using the Sheriff's
radio sites and their microwave network for a back-bone from remote receivers. In addition to the
normal 2 meter FM voice gear and HF voice, BCARES also had capabilities for digital messaging via
packet radio, more recently Win-Link, and (important for this newsletter) -- Amateur Television (ATV).
We added ATV capability in 1991, including an ATV repeater at a Sheriff's radio site. Analog NTSC
TV in the early days. We converted to hi-def. digital DATV in 2016. ATV was the most requested
communication service BCARES provided.
BCARES' (and most ARES groups) biggest problem now is the aging population of radio amateurs.
At BCARES meetings now, it is mostly a lot of gray (or bald) heads present. Many of us, myself
included, are no longer physically able to do the out in the field emergency response work anymore. I
actually recently felt I had to resign and turn in my Sheriff's ID badge because I was no longer able to
perform the required duties. I told our E.C. that I would no longer respond to emergency calls, but I
would contine to provide behind the scenes, technical assistance.
But even having a well run ARES group with lots of active volunteers will not always assure you of
having them available when the BIG ONE hits. Some of your most valued members may in fact be
victims themselves, not responders. I can speak from direct experience of being in that situation twice
in the last ten years. First in 2013 when Colorado experienced major floods, BCARES called but I
was unable to respond because I was dealing with my own flooded basement. That ended up being a
$50K loss. The second time it was far worse. In Dec. 2021, I had to emergency evacuate with my
dog from a rapidly advancing prarie fire. That fire ended up destroying 1000+ houses, including ours
and our neighboring daughter's.
So now back to Maui. Maui always had an ARES emergency coordinator (EC) and a VHF/UHF radio
in the EOC. I know the EC would man by himself the radio position at times of emergencies. He also
conducted a monthly net for reports of the tests of the emergency sirens. But to my knowledge, he
really didn't have any real members, nor a real live organization. Nothing like Boulder's BCARES.
Even within the Maui ham club, there really wasn't a good emergency comms base. We really only
had a small handful of really good operators. Now today, most of them are old and in poor health.
We did have one ham who stood out way above everyone else. I knew even if noone else responded to
the Lahaina fire, he would. It was Tom, NH6Y. Tom did provide assistance on his own for the
Lahaina fire relief efforts. The following article was provided to us by Tom relating his experiences.
Thank You Tom for your being there when needed ! Tom was really Mr. Maui Ham. He served as the
TV Rptrs Rptr-141.doc ( 9/12/23, kh6htv) p. 3 of 12
club president for many terms. He was also the driver behind getting the Maui Field Day operation
going and successful. He had perhaps the best ham station on the island working most all bands HF to
microwave. He was always elmering new hams. He worked with the Red Cross/Red Crescent in
Bangladesh. There, they rebuilt a combination HF/VHF radio network that served remote coastal
hurricane shelters. He hosted the HF DX beacon transmitter, KH6RS ( ). He and his wife, Leslie, hosted the MARC picnics many times. etc.
--- There isn't enough praise I can give to Tom.
73 de Jim, KH6HTV
Relief Supply Distribution Center
Napilli Park, West Side, Maui
Tom, NH6Y's, mobile ham station
at Napilli Park
A Maui Ham's Experiences Relative to the Lahaina Fire
Tom Worthington, NH6Y, Kula, Maui, Hawaii
I was called at 5 am on August 9th (the fire occured on August 8th) by the local head of the Red Cross.
She was unable to contact any of her volunteers on the Lahaina side of the island and was trying to get
some information about how many were in the Red Cross shelter. I tried calling the only active ham on
that side of the Island thru the linked repeater system, but he in fact had just managed to escape the
flames. When I was finally able to make contact almost two weeks after the fire, he told me that he and
his aunt, who owned a home in the fire area, had managed to get out just in time and spent that night in
their car, the next two nights in a Red Cross shelter, then another two nights in a Wailuku hostel before
flying back to Ohio. After the fire and before the road to Lahaina was opened a week later, local
people started ferrying supplies by boat from Maalaea, Molokai and even O’ahu. This effort was
independent from the Red Cross shelters and the FEMA response. The Red Cross had more than 2,000
people in congregate shelters but there were many residents on the west side who were without power,
communications and access to food. Volunteers went to Costco and bought water, SPAM, diapers etc.,
loaded them into small boats and headed to Kahana Boat Ramp (not really a ramp, the supplies were
hand carried thru the water to the shore) and set up impromptu distribution sites. A ham, who had not
even turned his Baofeng HT on since moving to Maui a couple of years ago managed to find a repeater
on Molokai that was still linked into the Maui repeater system. He asked for some help with
TV Rptrs Rptr-141.doc ( 9/12/23, kh6htv) p. 4 of 12
communications, and I got permission to get throgh the police roadblocks and went over to the West
side on Wednesday, a week after the fires. They were using marine VHF radios to coordinate with the
boats and the distribution sites. We deployed another ham to the harbor at Maalaea to try to get
information on when boats were leaving and what they had on them. I installed a VHF marine radio at
a distribution site that was starting up at Napili Park (note to self – never go to a disaster without the
tools to install coax connectors and a couple of extra 12 V power supplies). I also helped with some
power issues and getting their Starlink terminal operating. A couple of local companies installed a
large solar microgrid but for several days were unable to get it working reliably. I went over early each
morning and charged up their 3 kWh secondary backup battery and helped keep their growing array of
computers and printers running. The road opened on Thursday and most of the supplies started to
come by road. This local response is really quite amazing, it grew each day. More containers, more
tents, more NGO’s, organized activities for children, hot meals along with continuing distribution of
food and donated supplies. There is even a refrigerated container full of beef, direct from Molokai and
fresh produce from local farms. After two weeks most of the cell service is back and Spectrum and
Hawaiian Telcom have restored service to all but the heart of the burned area that is still inaccessible.
The people who run this site expect to be there for a long time.
I couldn’t help but notice that Starlink has completely taken over emergency communications. When I
first went out, there were a few terminals, a week later they were everywhere. At each parking lot there
was a van with a Starlink on top offering free Wi-Fi and phone charging. It takes about 15 minutes to
commission one and it can be done by anyone with some IT skills or a akamai teenager. The fact that
you can turn on and off the service by the month makes it an attractive alternative for emergency
73, Tom, NH6Y
Band-Pass Filter for 70cm, Narrow-Band, DATV
Jim, KH6HTV, Boulder, Colorado
In a previous ATV newsletter (issue #91), John, K0ZAK, had called our attention to an interesting
Band-Pass Filter he had found while surfing the internet. I had purchased one for evaluation just prior
to the Boulder fire storm in December, 2021, and then lost it (along with everything else ! ) in the
resulting fire. I had not gotten a chance to completely evaluate it and publish the results here in our
newsletter. See also issue #96. Well, I had remembered the basics that the filter was a three pole,
cavity filter with a -3dB band-width of the order of about 2.5 MHz. The specs. were typical Chinese,
claiming a tunable bandwidth from 0.6 to 8 MHz -- FALSE ! But still, it was otherwise a nice filter.
So fast forward to summer, 2023. In the meantime, we have modified our Boulder, Colorado ATV
repeater, W0BTV, to replace the 439.25 MHz analog NTSC receiver with a 439 MHz, 2 MHz bandwidth,
DVB-T receiver. We were attempting to get away from some nasty RFI. So, we thought why
not add this three pole Chinese filter in front of our new NB receiver. So we ordered one. Here now
is the results of our evaluation.
TV Rptrs Rptr-141.doc ( 9/12/23, kh6htv) p. 5 of 12
The filter is sold under the model number LBQ-
450. No manufacturer's name on it. It does say
made in Guangzhou, China. It is sold by several
Chinese vendors. The prices range all over the
place. I found the best deal was from a ham radio
store in Hong Kong called 409shop ( ). I paid $89 + $20 shipping.
Today (9/2), they are listing the price as $99. It
took right at a month for the mailman to deliver the
filter. When you place your order with 409, they
ask you to also specify the desired frequency.
They pre-tune the filter for you before shipping.
The specs. say it is tunable from 400 to 520 MHz. I was able to tune mine over the whole 70cm band
from 420 to 450 MHz. Here are the results of my measurements of S21, S11 & S22 on the filter as it
arrived, factory tuned to 439 MHz.
LBQ-450 BPF Filter: S21 Insertion Loss showing pass and stop band --- center frequency = 439
MHz, span = 50 MHz, 10dB/div & 5 MHz/div. Magenta trace is the resolution limit of the
measurement, i.e. -75dB down.
TV Rptrs Rptr-141.doc ( 9/12/23, kh6htv) p. 6 of 12
LBQ-450 BPF Filter: S21 Insertion Loss Pass Band
center frequency = 439 MHz, span = 10 MHz, 2dB/div & 1 MHz/div.
LBQ-450 BPF Filter: Return Loss Pass Band S11 (yellow) & S22 (magenta)
center frequency = 439 MHz, span = 10 MHz, 5dB/div & 1 MHz/div.
The insertion loss of -1.9dB was a bit higher than the Chinese spec. of < 1.5dB. The -3dB BW was 3
MHz. This should work well with a 2 MHz NB DVB-T transmitter or receiver. The return loss was
quite good showing well in excess of -20dB over much of the pass band. The skirts on the stop band
looked nice. The filter should work well in a 70cm, in-band, repeater. The stop band rejections were
seen to be about -30dB (±5 MHz), -48dB (±10 MHz), -56dB (±15 MHz), >-60dB (±20 MHz)
TV Rptrs Rptr-141.doc ( 9/12/23, kh6htv) p. 7 of 12
for Amateur 70cm & 33cm Bands
We have recently discovered still another low cost, consumer grade, DVB-T receiver which will in fact
easily tune both our 70 and 33 cm amateur radio bands. We DATV hams here in Boulder, Colorado
for several years now have been using as our primary receivers some "combo" boxes. Combo
meaning they were dual DVB-T for VHF/UHF terestrial broadcast and DVB-S for L-band, IF use with
LNBs and satellite dishes. We have written about them in previous issues of this newsletter. Over
the years we have had to change suppliers as they sometimes changed the firmware to versions which
would no longer tune the 70cm band, and also sometimes simply disappeared from the market. We
have warned our readers in the past "Buyer Beware" -- not all of these consumer grade receivers
would work on 70cm, even if their advertized specs. for frequency coverage implied they would. Best
to only buy what other hams have found actually works.
So, this past spring, once again our favorite combo receiver was no longer available, so I searched the
internet and found a new one listed which actually was available in stock in the USA for immediate
delivery. So, I bought one for evaluation. I found that it worked not just on 70cm band, but also the
33cm band. So, I have since purchased ten more of them and am offering them for resale to other
ATV hams. (already sold 4 of them ! ) To make it easy for newcomers, I am pre-programming the
receiver to tune the standard, 6 MHz, ATV channels on both 70 and 33cm bands. Because the antenna
TV Rptrs Rptr-141.doc ( 9/12/23, kh6htv) p. 8 of 12
connector is "weird" and not commonly found in the USA, I am also including a couple of coaxial
adapters to provide either F or SMA input.
So what is this new receiver? It is the GT-Media, model V7-PRO. Detailed specs. are available
from GT-Media web site: ... DVB-S2XT2-
The manufacturer's specs. for DVB-T are 174 to 862 MHz. I have tested the receiver and found that it
could actually be programmed for DVB-T as low as 100 MHz and up to 999 MHz. 100 MHz was the
lower limit on my Hi-Des HV-320 modulator. It only works with 6, 7 or 8 MHz band-width signals.
This receiver will not work for any repeaters using narrower band-widths. The antenna connector is
the European cable TV connector called a PAL. I have tested the sensitivity of the receiver and
actually found it to be more sensitive than the older combo receivers or the Hi-Des receivers. I
measured it to be about -97dBm. Adding a low noise preamp improved this number by a couple of dB.
Dual, independent A/V outputs are provided, HDMI and analog composite video. The receiver also
has a nice digital video recorder (DVR) capability. It will record incoming video onto a USB memory
stick (thumb drive). I have not tested the receiver for L-band, DVB-S, operation as I do not have any
DVB-S equipment in my ham shack.
The instrucion manual provided with the receiver "sucks". Typical Chinese manual, not worth the
paper it is printed on. Therefore, because I am reselling pre-programmed receivers, I felt it was
important to also provide the user with a good instruction manual. I have thus written up a new
manual as my app. note, AN-66 and posted it on my web site,
73 de Jim, KH6HTV, Boulder, Colorado
W0BTV - ATV Repeater Status Update:
The repeater has been repaired and is ready to be transported back to the repeater site. A new LBQ-
450, narrow-band, band-pass filter has finally arrived from Hong Kong. It was retuned to 441 MHz
and is now installed in the repeater. It has -1.7 dB insertion loss and 3 MHz BW. ( See the previous
article in this newsletter for more details about this filter ) The last remaining item was for Don,
N0YE, to squirt some magic RAID on the remaining buggy lines of firmware code for the Arduino
micro-computer. He was successful on Wed. Sept. 6th. All functions now seem to be operating
With the newly, reconfigured repeater again functional, we have updated all of the documentation. It
is now available on line at The new relevant app. notes are:
AN-51d "W0BTV Boulder, Colorado - Digital Amaeur Television Repeater"
( basically operational details for users, including new rf coverage maps )
AN-52a "Boulder, Colorado ATV Repeater - History" (updated now to 2023)
AN-53d "W0BTV Boulder, Colorado Digital ATV Repeater Technical Details"
TV Rptrs Rptr-141.doc ( 9/12/23, kh6htv) p. 9 of 12
Don, N0YE, has made an appointment with our contact at the repeater site for us to gain access next
Wednesday (9/13) to re-install the repeater. Everyone is anxiously awaiting it's return to the air !
Using the BCARES 70cm only, in-band, portable repeater has been less than satisfactory in the
interium due to the serious, broad-band, RFI on the input frequency.
A very simple DATV repeater can be put together
almost instantly. Especially if it is a cross-band
repeater. The KH6HTV application notes, AN-
23e & AN-48, discuss DATV repeaters. For a
simple one, simply patch the HDMI output from
your receiver into the HDMI input of your
transmitter. Add an on-site control operator to manually switch the transmitter on/off and your are on
the air as a repeater.
If you want a more sophisticated DATV repeater,
the complexity then starts to go up exponentially.
Our Boulder, Colorado, W0BTV repeater is an
example. It is documented in our app. notes, AN-
51d & AN-53d. ( all app. notes available at ) If you are going to add
additional receivers, or a local camera, and/or also
want to add a video IDer, then you will be needing
a means of automatically switching your video
sources. Perhaps the easist method is to use what
used to be called a "Quad Processor", or today's
prefered internet search term "Quad Viewer". For digital video with HDMI, they used to be extremely
expensive, costing well over $1K. But today, their prices now are dirt cheap. A quick google search
will come up with a whole lot of "hits". I even found one listed for as low as $30 bucks (but with no
However, for a repeater, you will need to have some means of automatically controlling the Quad
Viewer. All of them come standard with an IR remote control. But if that is the only way to control
the box, that means you then need to start hacking the remote to operate it automatically by your
repeater's controller. What is more elegant is to find a Quad Viewer which provides a true computer
control input port, such as USB or RS-232. Be careful however, when shopping, the photos of some
boxes show a USB connection, but they most times are not actually for computer control, but simply
for the factory to install the firmware, or they advertise as "fireware up-grade capability". Careful
shopping, (i.e. google surfing), and you will find some boxes which in fact have an RS-232 interface.
They typically will be a bit more expensive, but not a deal breaker and definitely easier than trying to
TV Rptrs Rptr-141.doc ( 9/12/23, kh6htv) p. 10 of 12
hack an IR remote control. A quick google search and I found right away three quad boxes with RS-
232 or USB ranging in price from $90 to $190.
Way back in 2018, when we built our W0BTV repeater, the quad viewer with RS-232 we used then
was made by the OREI company and was their model HD-401MR and cost us $90. OREI still sells
that model, but it no longer includes the RS-232 interface. Plus,then OREI did not supply as part of
the documentation how to use the RS-232 port. We had to beg the factory to provide us the code and
then Don, N0YE, had to figure out how to proceeed from there. OREI does now sell a similar unit
with RS-232 for $200. It is their model UHD-401MV.
OK, there comes the rub --- documentation. When selecting a quad viewer with RS-232 (or USB)
interface control capability, make sure first before ordering that they will also supply you with the
appropriate documention on how to use not just the front panel buttons, but also the RS-232 or USB
The first box I found at only cost $90, but no documentation included. The next
box I found at (also Amazon) cost $115. It had a micro USB port to be used for
either software control or firmware update. Their web site does provide a downloadable USB driver
for either Windows, Mac or Linux. The most expensive box I found was $189 from Amazon was
made by Yinker with RS-232. It did in fact have a downloadable manual which included the RS-232
commands. ( Disclaimer: ---- I have not purchased, nor evaluated any of these mentioned items. So
I can't vouch for their performance, or lack thereof. )
Another nice, but not mandatory feature for a quad viewer is what is the power source? Most A/V
gear seems to all like to be powered by USB, 5 Vdc wall warts. For our repeaters and other DATV
ham gear, we like to use 12Vdc. So finding a 12Vdc quad viewer is a plus.
73 de Jim Andrews, KH6HTV, Boulder, Colorado
TV Rptrs Rptr-141.doc ( 9/12/23, kh6htv) p. 11 of 12
Haswell BIG Antenna Open House
The Deep Space Exploration Society will hold its
annual open house on September 16, 2023, at the
Plishner Radio Telescope Site near Haswell,
Colorado. Visitors will be able to hear their voices
bounce off the moon using a 60-foot dish antenna
operating on the 1296 MHz band. There will be
tours of the new building, the communications
trailer, and the HF/6-meter remote station in the
underground bunker. There will also be a science,
technology, engineering, mathematics (STEM) and
amateur radio event with several optical telescopes
on site for viewing the skies during the day and
night. More information is available at
OE7forum: Darko, OE7DBH, writes --- "Forum operator has announced that OE7forum will be
removed on January 1st, 2024, so all of my entries will no longer be accessible. If you think that one or
the other information published there will be of interest to you in the future ( e.g. BU500 UPconverter ,
3LNC70, DVB-T topic and other my projects ), please download it immediately and save it on your
W0BTV Details: Inputs: 23 cm Primary (CCARC co-ordinated) + 70 cm secondary
all digital using European Broadcast TV standard, DVB-T 23cm, 1243 MHz/6 MHz BW
(primary), plus 70cm (secondary) on 441 MHz with 2 receivers of 6 & 2 MHz BW
Outputs: 70 cm Primary (CCARC co-ordinated), Channel 57 -- 423 MHz/6 MHz BW, DVB-T
Also, secondary analog, NTSC, FM-TV output on 5.905 GHz (24/7 microwave beacon).
Operational details in AN-51c Technical details in AN-53c. Available at:
W0BTV ATV Net: We hold a social ATV net on Thursday afternoon at 3 pm local
Mountain time (22:00 UTC). The net typically runs for 1 to 1 1/2 hours. A DVD ham travelogue is
usually played for about one hour before and 1/2 hour after the formal net. ATV nets are streamed live
using the British Amateur TV Club's server, via: Select ab0my or n0ye. We
use the Boulder ARES (BCARES) 2 meter FM voice repeater for intercom. 146.760 MHz ( -600 kHz,
100 Hz PL tone required to access).
Newsletter Details: This is a free newsletter distributed electronically via e-mail to
ATV hams. The distribution list has now grown to over 500+. News and articles from other ATV
groups are welcomed. Permission is granted to re-distribute it and also to re-print articles, as long as
you acknowledge the source. All past issues are archived at:
TV Rptrs Rptr-141.doc ( 9/12/23, kh6htv) p. 12 of 12
Free advertising space is offered here to ATV hams, ham clubs
or ARES groups. List here amateur radio & TV gear For Sale -
or - Want to Buy.
ITEMS FOR SALE (see our web site for details)
Tektronix 1710J
NTSC Waveform Monitor
Tektronix 1420
NTSC Vector Scope
Millen Antenna Bridge ... tr-141.pdf
Prispevkov: 1012
Pridružen: 28 Okt 2004, 21:07

Re: revija ATV

OdgovorNapisal/-a s58ru » 19 Sep 2023, 22:19

TV Rptrs Rptr-142.doc ( 9/18/23, kh6htv) p. 1 of 11
Boulder Amateur
Television Club
TV Repeater's
September, 2023
3ed edition, issue #142
BATVC web site:
ATN web site:
Jim Andrews, KH6HTV, editor -
W0BTV is Back on the Air ! ! !
Finally ! -- On Wed, Sept. 13th, trustees Don, N0YE, & Jim,
KH6HTV, were finally able to reinstall our Boulder, Colorado, DATV
Repeater. It is once again, back in it's home on the mesa south-west
of the city of Boulder. We welcome all ATV users back again and
hope it sees a lot of useage.
The basic repeater is all digital running DVB-T. The main transmitter
is on 70cm with DVB-T. It is on 423 MHz with a 6 MHz band-width
signal on channel 57. The transmitter puts out 5 Watts (+37dBm)
(avg) to a DB-Products, DB-411, four element co-linear antenna
(+11dBi gain with a cardiod pattern). We share the antenna with the
Boulder Amateur Radio Club's 70cm FM voice repeater.
The repeater is a cross-band repeater (23cm in / 70cm out). The input
frequency is 1243 MHz, again with 6 MHz BW, DVB-T. Our receive
antenna is a Diamond X-6000, tri-band (2m/70cm/23cm) with +10dBi,
omni-directional gain on 23cm.
We also have a secondary, analog, FM-TV transmitter on the 5 cm
band. It's frequency is 5.905 GHz. It puts out 2 Watts to a Laird
model OC515010H, omni-directional, horizontally polarized antenna
with 10dBi gain. This transmitter runs 24/7 as a microwave beacon.
TV Rptrs Rptr-142.doc ( 9/18/23, kh6htv) p. 2 of 11
Full details about the W0BTV - DATV Repeater can be found in application notes,
AN-51 & AN-53, on our web site at:
TV Rptrs Rptr-142.doc ( 9/18/23, kh6htv) p. 3 of 11
The above map shows the predicted RF coverage area for our W0BTV, 70cm, Transmitter. This map
was calculated using the on-line rf prediction program, Radio Mobile. The receiving stations are
assumed to be using a 6 element, yagi antenna with 11dBi gain and mounted at 10 meters elevation.
50 ft, of LMR-400 coax was assumed. Also assumed was the receiver is using a good low noise
figure pre-amp. Plus the antenna is in a good location with no RFI and minimal multi-path. Under
these ideal conditions, the ultimate receiver sensitivity is of the order of -99dBm. The yellow shaded
areas are predicted really weak signals of -99 to -90 dBm. The green shaded areas are for stronger
signals > -90 dBm. TV signals reach all the way to the Wyoming border, just south of Cheyenne.
The repeater covers a good portion of the prarie portion of the northern front range, but with zero
coverage into the mountains to the west.
TV Rptrs Rptr-142.doc ( 9/18/23, kh6htv) p. 4 of 11
BUGS Remaining: Unfortunately, all is still not perfect with the repeater. On our next ATV net
after reinstalling the repeater, we discovered still yet another Arduino code "bug". After the repeater
has been on the air continuously for 10 minutes, to meet FCC requirements, we switch over to the quad
display for a few seconds and then back to full screen. Using the quad screen allows us to ID the
repeater because the lower right quadrant always displays our continuously running ID slide show. So
the "bug" is after doing this switch, we then lose the audio from the incoming TV signal. Bummer !
So, Don, N0YE, will be making yet another trip back up the hill to the repeater site. This time he will
be lugging along his PC laptop and try to modify the Arduino code to kill what we hope is the last and
final "bug" ! Wish him LUCK !
HDMI QUAD VIEWER FEED-BACK: As a result of our article in the previous
newsletter, we received this e-mail and interesting article from Dave, G8GKQ.
"Hi Jim --- I was interested to read about your use of a 4-way HDMI switch for a basic repeater. We
have done the same thing, and it is now in use at GB3HV (currently off-air due to site change) and
GB3DO which sometimes streams here
We used a Raspberry Pi to provide full control, and to emulate the IR codes to switch the HDMI. It has
proved to be a very easy way to control the switch."
BATC ATV Repeater Controller
Dave Crump, G8GKQ & Noel Matthews, G8GTZ
Over the last 10 years, the ATV community has successfully migrated to digital transmission standards
which have enabled transmission of greater resolutions than the 720 x 576, PAL standard and the Ryde
receiver has enabled this high quality video to be available in HDMI format.
However, most ATV repeater systems are still using PAL based video switching and logic systems with
the resulting loss in video quality. In order to encourage repeater groups to upgrade their systems,
BATC has developed a simple repeater controller enabling the use of consumer HDMI switches as a
repeater video switch.
The controller provides a flexible way to display captions and images and can be used to replace
existing controllers. In order to provide backwards compatibility and enable to controller to be fitted to
an existing repeater, an analogue switcher can be controlled using the GPIO outputs and the controller’s
HDMI caption output can be converted to composite video.
Inputs from existing analogue receivers can be converted to HDMI for use in the system using the
HDMI converter described in another article in this issue.
TV Rptrs Rptr-142.doc ( 9/18/23, kh6htv) p. 5 of 11
OVERVIEW: The core of the system is a
consumer IR controlled HDMI switch –
these are readily available for Multimedia
home systems from the normal sources and
come in 2 / 4 / 6 / 8 input configurations.
The switch will be fed with HDMI outputs
from Ryde receivers, BATC streaming
receiver, Analogue to HDMI converters and
graphics generator.
The switched HDMI output is fed to a video
encoder / modulator and also to provide
streaming on the BATC live streaming
Every repeater is different and the controller is designed as a core logic that can be used as the basis for
an ATV repeater. The design is flexible with a large number of parameters in a text editable
configuration file so that users can configure it to meet their own needs.
TYPICAL OPERATION: The BATC repeater controller controls single or multiple video switchers
either by InfraRed, I2C, webhooks or GPIO pins. It also generates a carousel of scenes and has an onboard
DTMF decoder. The carousel can be configured to show up to 99 scenes. The content and
duration displayed of each scene is set in the configuration file and the scene can be one of the
The carousel can be configured to show up to 99 scenes. The content and duration displayed of each
scene is set in the configuration file and the scene can be one of the following:
1. Status screen generated by the controller
2. jpg or png images played out by the controller
3. Video files (in future release).
4. Any input on the video switcher, so can display inputs such mast cams,
weather stations or Quad video displays.
The still images are read each time before display so can be regularly updated by an external source.
VALID SIGNAL INPUT: On receipt of a valid signal from, for example, a Ryde receiver, the
controller will key the transmitter, play an image for .5 seconds indicating which input has been
activated and then switch to that input. When the receiver closes, the logic will play a "K" image and
optional "K" in Morse and go back to the carousel.
The receiver input switching line can be directly from a Ryde receiver or an external source such as a
sync detector on an analogue source. Note do NOT exceed 3.3 volts on the GPIO input.
TV Rptrs Rptr-142.doc ( 9/18/23, kh6htv) p. 6 of 11
IDENT SIGNAL: In order to comply with licensing regulations, a video and/or audio ident can be
generated at an interval set in the config file.
DTMF CONTROL: An on-board DTMF decoder will allow input selection by remote control and
also enable GPIO pins to be toggled to enable the control of external equipment.
POWER SAVING: To enable power saving by turning the repeater transmitter off during quiet
periods, a number of options are available such as, only key the transmitter when in repeat mode, do
not key the transmit during the night time and only key the transmitter to display the carousel for the
first 30 minutes of every hour.
REPEATER CONTROLLER: The BATC repeater controller runs on Raspberry Pi4 (2 GB
memory) which has several functions:
CONTROL of the VIDEO SWITCHER: The preferred method of control is via Infra-Red
commands sent by an IR diode, recovered from an old remote control, connected to pin 12 on the RPi
GPIO port. The IR commands sent are totally programmable in the config file.
To increase the number of inputs available, 2 separate IR transmitters can be connected to enable a
second HDMI switch to be controlled.
The controller can also control a video switcher using the RPi GPIO lines – these lines are 3.3v logic
and the outputs must be buffered.
At the request of Justin G8YTZ, Dave G8GKQ (author of the controller software) has added the ability
to controller an external video switch such as the ATEM mini using webhooks – see the separate article
on the Alternative Repeater controller in CQ-TV.
GRAPHICS GENERATION: The RPi generates captions and plays out carousel images using the
HDMI port which should be connected to an input on the video switcher. A future update of the
controller may enable the composite video port to be used for playout or alternatively an HDMI to
composite converter can be used to output to an analogue switcher.
DTMF DECODER: The on board DTMF decoder is fed via the mic input on a standard USB audio
dongle. All DTMF command sequences are programmable and can be set to select video inputs, toggle
GPIO output pins, send i2c commands and several keeper only commands such as turn the transmitter
on / off and reboot the controller.
GPIO CONNECTIONS: The repeater controller uses the RPi GPIO port for the following:
1. Accepts up to 8 signal detect inputs
2. IR / I2C drive output
3. GPIO outputs to control video switchers.
4. Auxiliary equipment control outputs
TV Rptrs Rptr-142.doc ( 9/18/23, kh6htv) p. 7 of 11
The exact pins used for each function are set in the configuration file.
CONFIGURATION FILE: The controller is designed as a core logic with a large number of
parameters in a text editable configuration file so that users can configure it to meet their own needs.
For full details on the controller configuration see this wiki page: ... figuration
AUDIO SWITCHING: Whilst HDMI switchers will switch any audio carried in the HDMI signal,
a repeater system may require additional control over the audio such as talkback audio insertion and
multiple audio mixing when in quad mode.
The Ryde receiver and the BATC composite to HDMI converter do provide selectable analogue audio
outputs via the RPi multi pin jack socket.
To enable this to be used, the BATC controller can control an optional i2c audio switcher – see the
separate article in this CQ-TV for more details.
HDMI BUFFERING: Experience has shown that although the switches are advertised as seamless,
the switch between sources is not truly seamless.
This glitch is enough to cause any encoder following the switch to hang up. This problem could
possibly be solved by using another HDMI seamless switch as a buffer between the main switch and
the encoder. This may seem extravagant but is cheaper than a designed HDMI buffer!
TV Rptrs Rptr-142.doc ( 9/18/23, kh6htv) p. 8 of 11
SOFTWARE AVAILABILITY: The controller software is available for download from the BATC
Github page ... b/atv-rptr
We believe that whilst this is a very important project for the ATV community the actual number built
will be relatively low and so do not intend to put the pre-programmed SD cards in the shop. However,
if you would prefer to buy a pre-programmed SD card, please send an email to
MORE INFORMATION: More information, including a comprehensive guide to configuring all
the options available, GPIO pin outs and DTMF control is available on the BATC wiki at
There is also a forum thread where you
can get support from the community of users and details of the latest updates will be published.
Apartment dwellers can also participate and have fun with ATV.
Our own Clyde, KB0AMJ, is a classic example. A couple of
years ago, Clyde read about the Boulder ATV repeater in the
Denver Radio Club's newsletter. It picqued his interest. Even
after we did an RF path profile from the Boulder ATV repeater to
Clyde's apartment QTH in Arvada and said it would be impossible
to get a signal to/from there, that didn't stop Clyde.
Clyde says --- "I've been in ham radio off & on since 1987. My interests include photography, art,
birding, ham radio (KB0AMJ), science, and motorcycling. I have over 30 years experience in
computing and information processing. I am now retired and enjoying life. I blog and post photos on
my web site at:"
Clyde also said to himself -- "Well if I
can't do ATV at home, maybe I can do
it mobile instead." Clyde has proved
that is possible. He is a regular checkin
to our weekly Boulder ATV net. His
favorite mobile ATV location is north
of Arvada on state highway, CO-128
near the giant windmills at the National
Renewal Energy Labs. From there, he
has a 9 km, direct line of sight path to
the Boulder ATV repeater.
TV Rptrs Rptr-142.doc ( 9/18/23, kh6htv) p. 9 of 11
Clyde outfitted himself with a "To Go" ATV kit which
installs rapidly in his Toyota pick-up truck. With it he is
able to transmit hi-def, 1080P video on 23 cm band while
simultanously watching the hi-def, digital ATV repeater's
output on the 70 cm band. Most all of the various
electronic components are all mounted on a wooden board
which sits nicely on the passenger seat in his truck. He
powers it all with a battery packaged in an ammo carrier
box. Every thing works off of +12Vdc. He only needs a
single antenna which is a magnetic mount, tri-band
(2m/70cm/23cm) mobile whip antenna. Here is the list of
the gear Clyde uses. He also has sent us some photos of
the setup.
DVB-T Transmitter / Receiver:
1. Hi-Des, model HV-320E, DVB-T Modulator
2. KH6HTV Video, model 23-11A, 4 watt, 23cm RF Linear Power Amplifier
3. Combo DVB-T & DVB-S, DVB-T receiver
4. Lilliput model A7S, 7" full HD video monitor
5. Zoom Q2n-4K Handy Video Recorder / Camera
Antenna System:
1. Diamond model NR2000NA, 2m/70cm/23cm, mobile whip antenna
2. Diamond model DPK-4NM-N, 4" dia. magnetic mount base, N connector + coax
3. Diamond model MX3000N, antenna triplexer, 2m/70cm/23cm
Battery System:
1. Hardened Power Systems model Pilot G2 --- LiFePo4 battery, 33 Amp-hour, in ammo can
2. Powerwerx, model PD-8 power distribution block
TV Rptrs Rptr-142.doc ( 9/18/23, kh6htv) p. 10 of 11
Clyde's battery box & video camera
ATV in Slovenia Rudi, S58RU, has sent us some photos of his 9cm (3.4 GHz), ATV gear
NEWS from San Diego: Our membership team is still very active and still with
the STEM Science Programs through JPL, NASA and the NSF. Membership holds steady with our
senior group and younger team' seventy one total. Systems are working well with no outages nor
equipment failures. 2024 will bring new upgrades to our site(s) with antenna replacements ,system
computers and management software. CubeSat Team reports progress in project funding and
development. 73 de Mario, KD6ILO
TV Rptrs Rptr-142.doc ( 9/18/23, kh6htv) p. 11 of 11
W0BTV Details: Inputs: 23 cm Primary (CCARC co-ordinated) + 70 cm secondary
all digital using European Broadcast TV standard, DVB-T 23cm, 1243 MHz/6 MHz BW
(primary), plus 70cm (secondary) on 441 MHz with 2 receivers of 6 & 2 MHz BW
Outputs: 70 cm Primary (CCARC co-ordinated), Channel 57 -- 423 MHz/6 MHz BW, DVB-T
Also, secondary analog, NTSC, FM-TV output on 5.905 GHz (24/7 microwave beacon).
Operational details in AN-51c Technical details in AN-53c. Available at:
W0BTV ATV Net: We hold a social ATV net on Thursday afternoon at 3 pm local
Mountain time (22:00 UTC). The net typically runs for 1 to 1 1/2 hours. A DVD ham travelogue is
usually played for about one hour before and 1/2 hour after the formal net. ATV nets are streamed live
using the British Amateur TV Club's server, via: Select ab0my or n0ye. We
use the Boulder ARES (BCARES) 2 meter FM voice repeater for intercom. 146.760 MHz ( -600 kHz,
100 Hz PL tone required to access).
Newsletter Details: This is a free newsletter distributed electronically via e-mail to
ATV hams. The distribution list has now grown to over 500+. News and articles from other ATV
groups are welcomed. Permission is granted to re-distribute it and also to re-print articles, as long as
you acknowledge the source. All past issues are archived at:
Free advertising space is offered here to ATV hams, ham clubs
or ARES groups. List here amateur radio & TV gear For Sale -
or - Want to Buy ... tr-142.pdf
Prispevkov: 1012
Pridružen: 28 Okt 2004, 21:07


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