Re: revija ATV

Amaterska TV

Moderator: s55o

Re: revija ATV

OdgovorNapisal/-a s58ru » 23 Nov 2023, 17:14

TV Rptrs Rptr-147.doc ( 11/22/23, kh6htv) p. 1 of 12
Boulder Amateur
Television Club
TV Repeater's
REPEATER
November, 2023
3ed edition, issue #147
BATVC web site: www.kh6htv.com
ATN web site: www.atn-tv.com
Jim Andrews, KH6HTV, editor - kh6htv@arrl.net www.kh6htv.com
NEW, Hi-Des 13cm DTV
LINEAR RF POWER AMPLIFIER
TV Rptrs Rptr-147.doc ( 11/22/23, kh6htv) p. 2 of 12
We have just received this communciation from Darko, OE7DBH
"We ( HiDes and OE7DBH ) are currently developing a new 2-stage power amplifier for the 13cm
(2.4 GHz) amateur radio band, also good for DVB-T operating mode. Expected DVB-T performance
is around 5 Watts output in hardware configuration with HV320. Gain around 45 dB. Here are a few
pictures from the first test version."
Editor's Note: Looking carefully at these photos we can gain some additional info about this new
amplifier being developed. The interior photo shows two gain blocks, U2 & U3 in cascade. U2 is
the driver MMIC. U3 is the final power amplifier block with heat sinking. J3 (lower right) is the
SMA input. J4 (upper left) is the SMA output. J3 (top upper left) is an rf output signal sample port
SMA. U4 (upper left) is a circulator with a 50 Ω termination on it's 3ed port. It is used for VSWR
isolation to protect the final amp. Reading the hand written labeling on the prototype amplifier we
see that the DC power supply is 27 Vdc. The test rf input power was 0.15mW (-8dBm). The rf
power output was 44 Watts (+46dBm). Thus implying a gain of 54dB. The J4 test port is labeled as
33mW (+15dBm)
=========================================================================
Free Space Laser Communications Q ?
Mario, KD6ILO
The San Diego ATV Society and myself are experimenting and using Free Space Optics [Laser]
Communications for our 2024 project. WE have one(1) working system at our Carlsbad lab sending a
beam 13 miles line-of-sight to our Ramona site {voice, video and data at Gigabit speeds.
TV Rptrs Rptr-147.doc ( 11/22/23, kh6htv) p. 3 of 12
Q? 1: I was asked why use lasers for Amateur TV and cost?
You can assemble a simple test system using form factor
computer(s) such as the Raspberry pi 5 for example and other
models of similar cost. Using low cost effective laser
transmitter/receiver assemblies on the market. Knowing how to
write basic code helps.
Q? 2: Yes AREDN MESH can benefit from this too, especially when data from sources which send
heavy message traffic, video streaming technology from multiple venues, there's endless possibilities.
--Advantages of using laser communications over radio waves, increased bandwidth, enabling the
transfer of more data in less time and quicker, sharper, video images. The improved technology of
today is much smarter, smaller, lighter, and takes up lass space to assemble as I've found out first hand.
That's why our team will bring it into our amateur radio lab in Carlsbad, CA with the help of grant
funding and will acquire products from the Mitsubishi products lab in Japan. Optical-Data modems
help as a gateway {light to binary data} and vice versa speeds 1- 7.2 Gbit/s flawless and to achieve
100% throughput at all times. No bandwidth or RF challenges, just free space communications.
Laser KD6ILO laser comms work bench
Q? 3; How are aiming the laser over a long distance to the receiver unit?
Answer: As for alignment, for me I don't bother with a gimbal to point the laser beam. Instead, I used a
custom error-signaling system that adjusts the entire LCT itself to point precisely towards the receiver
optical lens. Like I said earlier, knowing coding helps. This allows the optical components to be
miniaturized.
My home built system uses surplus parts and buying some new components such as for my receiver
makes for a less costly mistake on my part budget wise. It works, I'm just getting my laser modem
setup with a special router, a LinkStar H68K. then put everything in a nice package unit.
Q? 4: Can you give us a project that your STEM students use for Laser communication?
Answer: Sure! here is the link information;
https://electroniqueamateur.blogspot.com/Optical receiver prototype for laser communication terminal (LCT)
TV Rptrs Rptr-147.doc ( 11/22/23, kh6htv) p. 4 of 12
In conclusion we must also keep up with technology as it takes hold over us and time this is not new
but improvements over time. Amateur Radio must keep pace so we can educate our younger hams in
our community {STEM} as we have in our classes on a weekly basis. We have moved forward from
analog, digital DVB-T,S, ATSC and now newer laser upgraded technologies. 2024 will be a big step
forward. I will see NASA's new space Internet DSN grow with improvements. I know what's
coming...do you?
73 de Mario, KD6ILO
LCRT Optics - Ramona, CA
KD6ILO Test Station LCT Platform
Carlsbad, CA
Mobile, Portable LC Transceiver Station
=========================================================================
Editor Reminisances about Laser Comms: Mario's recent notes above about his new
interest in optical communications, caused me to reflect upon my early career. While working for
the National Bureau of Standards (NBS, now NIST) in Boulder, Colorado -- they sent me and my
family on a one year assignment in 1971-72 to work in the French national telecom labs (CNET) in
Lannion, Brittany, France. CNET was the French equivalent of our Bell Labs. There I was assigned to
work with some other engineers on the birth of fiber optics for telecom. In particular, I was measuring
TV Rptrs Rptr-147.doc ( 11/22/23, kh6htv) p. 5 of 12
laser pulse dispersion in the picosecond region in glass fibers. During that year, we and others made a
couple of major break-throughs which were land marks in proving fiber optics could eventually replace
conventional wired telecom. First was a dramatic improvement in optical fiber attenuation. In 1971,
we were working with fibers which had 1,000dB/km loss ! Right -- I said 1000 dB ! That year,
glass chemists were able to get the loss down dramatically to 20dB/km. That showed it was suddenly
feasible to send comms over long distances. Today, optical fiber losses are even much lower. The
second major break through was the development of a laser diode which would work continuously
(CW) at room temperature. Previously the only laser diodes which would work CW had to be cooled
to cryogenic temperatures.
After returning back to Boulder and NBS a couple of years later, I designed and built a couple of
complete, working fiber optic telecom demonstration set-ups to send full band-width (4.2 MHz),
baseband, NTSC, color TV signals over a fiber optic cable. The first one was analog. I AM
modulated an IR LED with the TV signal. At the receive end I had an avalanche photo diode detector
followed by a wide-band video amplifier with AGC.
The second, much more complicated one was a 100 Mbps digital system. I designed and built all of
the various component pieces with one exception. The only commercial piece of gear I used was a
then state-of-the-art 8 bit, A/D converter running at 10 MHz clock rate. The A/D was in a full 3" high,
19" rack mount cabinet ! A real dinosaur by today's standards ! My fiber optic telecom system ran
at an overall data rate of 100 Mbps. We didn't do any data compression in those days. Simply sent
the raw, un-compressed video signal as an RZ serial data train. My 100 Mbps data package consisted
of the first bit always being a "1" as sync, followed by the 8 bits of video from the A/D, plus 1
additonal data bit for another lower speed data channel. 100 MHz ==> 10 ns long data with each data
bit occupying 1 ns. The digital transmitter included a 100 MHz xtal clock, the 8 bit, BCD, A/D
converter, parallel BCD data to serial converter, etc. All done in ECL.
I then pulse modulated on & off a semiconductor laser diode with the 100 Mbps data steam. The
laser's light beam was launched into a muli-mode fiber optic cable. At the other end of the fiber cable
was an avalanche photo diode detector followed by a broad-band amplifier. This then went to my
digital receiver which included a clock recovery circuit, data detector, serial to parallel converter, then
an 8 bit D/A converter, and video amplifier. The digital receiver was again done in ECL plus discrete
components for my D/A design. Surprise ! It all worked !
When I gave a live demo of the system to the NBS staff, it blew them away at the time. They hadn't
seen such digital tech before. What was especially an eye-opener to them was digital quantization.
My live demo included disabling one or more of the 8 data bits and seeing what it did to the resultant
TV image on the video monitor.
What Mario is proposing is really nothing new. It is just that technology has improved a whole lot
since my early attempts in the 70s (50 years ago !). Here in Boulder by the late 70s, some E.E.
professors at the University of Colorado were experimenting with exactly what Mario wants to do. i.e.
send video data though the atmosphere using lasers and optics. Yes, they worked, but not without
issues. And Yes, it will work for Mario, but some of the same issues now as then. A couple of
Biggies that everyone will encounter are:
TV Rptrs Rptr-147.doc ( 11/22/23, kh6htv) p. 6 of 12
1. Antenna Pointing -- If you think it is difficult to align your 30dBi dish antenna for 10 GHz at a
target 10 miles away, try doing that with an infinitely narrower beam-width from a laser ! Not
impossible, but damm hard to do. Now try to stabilize it and keep it on target.
2. Atmospheric Effects --- We all know what happens to visibility on a foggy day. Light
propagation drops to very short distances. Plus even on a clear day, have you noticed wavy lines on
the horizon due to thermal effects ? i.e. all sorts of propagation issues to attenuate, scatter, distort
and bend our laser beams. For NASA and space laser comms -- not an issue, but here on Mother
Earth a big issue.
73 your editor, Jim, KH6HTV, Boulder, Colorado
=========================================================================
DVB-T Digital Parameters --
How do they impact system performance ?
Jim, KH6HTV
This is a report on some experiments performed to determine the impact of chosing various DVB-T
digital parameters upon the sensitivity of a DVB-T receiver. The tests were performed in a perfect
lab environment with a coaxial cable connection between the transmitter and receiver. They
obviously did not cover all of the nasty issues encountered out in the real world with radiated signals.
Issues such as multi-path, mobile flutter, RFI, etc. rear their ugly heads out there. Some of the digital
parameters are intended to deal with those but don't necessarily impact receiver sensitivity. To test
them, would require additional field testing.
The digital parameters considered are those which can be selected on the Hi-Des HV-320 modulator
using the windows PC program called AV-Sender. They include:
Media Configuration:
Video Encoding Type: MPEG2 or H.264
Video Encoding Resolution: 15 choices from Auto, 360x480 up to 1920x1080
Max Bit Rate: any arbitrary value may be entered up to the calculated theoretical upper limit
Video Encoding GOP (Group of Pictures) Length: any integer value. typical is 30 or 60
Video Encoding Frame Rate: we use 30 fps for the USA
Audio Encoding Type: MPEG2, AAC, or AC3, most common is MPEG2
Audio Encoding Rate: 96, 128, 192, or 384 Kbps
Transmission Configuration:
Center Frequency: 100 MHz to 2.6 GHz, in 1 kHz increments
Band-Width: 1.5, 2, 2.5, 3, 4, 5, 6, 7 or 8 MHz
Modultation Method (Constellation): QPSK, 16QAM, or 64QAM
Number of Sub-Carriers (FFT): 2K, 4K, or 8K
FEC - Forward Error Correction (Code Rate): 7/8, 5/6, 3/4, 2/3, or 1/2
TV Rptrs Rptr-147.doc ( 11/22/23, kh6htv) p. 7 of 12
Sync (Guard Interval): 1/32, 1/16, 1/8, or 1/4
Modulation Data Rate: Based upon the choices made in the above Trans. Config. parameters,
the computer then calculates a theoretical max. possible data rate. This is then taken into
consideration when selecting the video encoding data rate in the Media Config. Hi-Des
reccommends that it be set no higher than 80% of the theoretical max. This is to allow for the
audio data plus other overhead data to also be transmitted. For very low band-widths, an
even lower % should be used.
"Standard" Parameters: These are the values typically used by the Boulder ATV hams, plus they
are used in the Boulder, W0BTV repeater transmitter.
Media Configuration: HDMI, H.264, 1920x1080, 5.5 Mbps, 60 GOP, Audio = MPEG2, 96 Kbps
Trans Configutation: 6 MHz BW, QPSK, 8K sub-carriers, 5/6 FEC, 1/16 sync
Receiver Parameter Requirements: Fortunately, the DVB-T receivers are "smart". They work
automatically with any combination of the above parameters, except for band-width. They will even
switch seamlessly if the transmission parameters are changed abruptly mid-steam. The transmitter
sends out a meta-data header informing the receivers what it will be using.
Receiver Sensitivity Test Proceedure: The transmitter was a Hi-Des model HV-320E modulator. A
live HDMI video source was a DVD player playing a live action video with constant motion and audio.
The receiver was a Hi-Des model HV-110. Some tests also placed a low noise, pre-amplifer in front of
the receiver. The pre-amp was a KH6HTV model 70-LNA. The transmitter and receiver were
connected via a long coaxial cable permitting adequate seperation between the two units to minimize
any residual rf leakage coupling. The internal attenuator in the HV-320 was adjusted to provide
exactly 0 dBm rf average power at the far end of the coax cable. Additional attenuation was inserted
in front of the receiver with fixed 20dB & 30dB SMA attenuators plus a rotary step attenuator (0 -
69dB in 1 & 10 dB steps). The step attenuator was adjusted to determine the weakest possible signal
which still gave perfect P5 / Q5 video and audio. The signal level and resultant signal / noise ratio
were then recorded. An additional 1 dB of attenuation caused either freeze framing or complete loss of
signal. This state was also indicated by the Signal LED on the front panel of the HV-110. It flickered
red/green. The LED was solid green when receiving a P5 picture. The LED was solid red when no
signal was present at all.
TEST RESULTS -- RECEIVER SENSITIVITY for
VARIOUS DIGITAL PARAMETERS
QPSK vs. 16QAM vs. 64QAM: All were measured with "standard" parameters. Only items
changed were modulation method and video data rate. The "max" values are the calculated theoretical
max. possible encoding data rates. Hi-Des recommends we never exceed 80% of the max. The
measured receive sensitivities and resultant signal to noise ratios were:
QPSK (5.5 Mbps 7.32 max) = -94dBm / 8dB s/n (max s/n = 23dB)
16QAM (11.5 Mbps, 14.64 max) = -88dBm / 14dB s/n (max s/n = 26dB)
64QAM (16 Mbps, 21.96 max) = -80dBm / 22dB s/n (max s/n = 32dB)
TV Rptrs Rptr-147.doc ( 11/22/23, kh6htv) p. 8 of 12
conclusion: 16QAM is 6 dB worse and 64QAM is 14 dB worse compared to QPSK
QPSK - vary the Code Rate (i.e. FEC): measured with standard parameters. Only items changed
were FEC and video data rate. The measured receiver sensitivities were:
7/8 (6.0 Mbps, 7.68 max) = -93dBm / 9dB s/n 5/6 (5.5 Mbps, 7.32 max) = -94dBm / 8dB s/n
3/4 (5.0 Mbps, 6.59 max) = -95dBm / 7dB s/n 2/3 (4.5 Mbps, 5.85 max) = -96dBm / 6dB s/n
1/2 (3.5 Mbps, 4.39 max) = -98dBm / 5dB s/n
conclusion: Each step increase in FEC adds about 1dB improvement in sensitivity and required s/n.
But at the expense of considerable reduction in encoding data rate.
QPSK - 6 MHz BW vs. 2 MHz BW: measured with standard parameters. Only items changed were
band-width and video data rate. The measured receiver sensitivities were:
6 MHz BW (5.5 Mbps, 7.32 max) = -94dB / 8dB s/n
2 MHz BW (1.5 Mbps, 2.39 max) = --98dB / 8dB s/n
conclusion: Going from 6 to 2 MHz band-width buys 4 dB improvement in sensitivity, but at a
considerably lower data rate.
MPEG-2 vs. H.264 Video Encoding: No change was noted.
# Sub-Carriers - 8K vs. 2K: No change was noted
Guard Interval (i.e. Sync): Only items changed were guard interval and video data rate. No
change was noted.
Video Encoding Resolution: No change was noted.
Parameters for Best Sensitivity:
6 MHz BW = -98dBm Trans. Config = QPSK, 8K FFT, 1/2 Code (FEC), 1/16 Guard
Media Config = H.264, 1080P, 2.5 Mbps
2 MHz BW = -102dBm Trans. Config = QPSK, 8K FFT, 2/3 Code (FEC), 1/16 Guard
Media Config = H.264, 640x480, 1.2 Mbps
Add a Low-Noise PreAmp: measured with standard parameters.
6 MHz BW: HV-110 = -94dBm 70-LNA + HV-110 = -98dBm
2 MHz BW: HV-110 = -99dBm 70-LNA + HV-110 = -102dBm
Ultimate Performace: Best Sensitivitity Parameters + plus low noise preamp
6 MHz BW = -102 dBm / 5 dB s/n
2 MHz BW = -105 dBm / 6 dB s/n
LNA Conclusion: adding a low noise (NF < 1 dB) pre-amplifier improves HV-110 receiver
sensitivity by about 3-4 dB.
ATN-California, Recommended 2 MHz Parameters with 16QAM:
see the July, 2023, ATV newsletter, issue #135, page 5
TV Rptrs Rptr-147.doc ( 11/22/23, kh6htv) p. 9 of 12
Trans. Config = 2 MHz BW, 16QAM, 8K FFT, 3/4 Code (FEC) & 1/16 Guard
Media Config = MPEG2, 1280x720, 2.6 Mbps, & 30 GOP
HV-110 = -93dBm / 14 dB s/n 70-LNA --> HV-110 = -97dBm / 13 dB s/n
ADDITIONAL READING: If you want to find out a lot more about the various digital parameters,
or anything else about DVB-T (or DVB-S, DVB-C, etc.), I suggest the book I consider the "Bible"
for DTV. ------ "Digital Video and Audio Broadcasting Technology --- A Practical
Engineering Guide" by Walter Fischer (TV engineer at Rhode & Schwartz, Munich, Germany).
Springer, 3ed edition, 2010
=========================================================================
Another Mid-West ATV
Band Opening !
Photos are WB8LGA's analog ATV signal
from 90 miles to AH2AR's hamshack, along
with W8URI's distant 85+ mile DVB-T signal
also being received at AH2AR's shack in
Vandalia on Sunday, Nov.18th. ATV DX
continues to be alive and well within the
Midwest region. W8URI has built a 1 KW
70cm pallet amplifier, and was transmitting
about 130 watts on DVB-T. Two way DVB-T
and analog, A5 contacts were accomplished
with both stations. 73 de Dave, AH2AR
analog ATV digital ATV
FEEDBACK:
ATV Trivia: Alan, AD6E writes --- "Yes, it's
an amazing job of deep research by someone at
ARRL to find that photo. It makes me wonder what
else they could dredge up. ;-) I'm sure it's the only
one in existence of me standing next to an ARRL
banner. Here's another, but of Jim this time.
Kent, KH6CJJ writes --- "Nice picture of you and
Alan, Jim. Gee that seems so long ago! I am
reading this in Japan nearing the end of a 24 day
visit. Unfortunately, no ham radio contacts here
although a near miss. I need to wear a hat with my
call on it on future trips. Aloha, Kent"
TV Rptrs Rptr-147.doc ( 11/22/23, kh6htv) p. 10 of 12
Feedback on Remote Receivers: Mike, WA6SVT, writes --- "Great newsletter Jim! BTW,
you can set up the remote receiver for a 5 MHz bandwidth or the main receiver that way with the
remote at 6 MHz. Having a different bandwidth will allow the selection to take place and the users
would set up each bandwidth on a different channel but same center frequency. Simular way as using a
different PL tone for NBFM voice receivers." 73, Mike
W0BTV Repeater Status Update:
Recently Don, N0YE, made yet another trip up the hill to service
our repeater. This time he made a trip to the roof top to tighten up
the bolts on our receive antenna. He also replaced the Video ID
media player with a new unit and new USB memory. Once back
home, he tested the media player and decided that the problem
with the tearing of the video images was due to a defective USB
memory stick, thumb drive and not the media player itself.
We also still are having "flaky" issues with the repeater controller. Toning up the Quad Display mode
leads to unpredictable behaviour. Sometimes it works properly, other times not. Most recently it has
been dropping out of quad mode after a few minutes and then hanging up the repeater transmitter. The
only way out is to then tone in the control code for a System Master Reset-Boot. Never a dull
moment when you have a repeater ! ! !
=========================================================================
Disturbing RFI Products found on AliExpress !
On a recent Boulder ATV net, Colin, WA2YUN, showed us a new, Chinese, low cost, 23cm amplifier
he had found on Ali-Express. Looking at the link to it Colin sent me I also noticed some other items
advertised. I was really troubled by their presence. But considering the current world situation with
wars being fought in the Ukraine and Israel/Gaza with a proliferation of war drone aircraft, I guess I
shouldn't be surprised. So just what did I find ? Under the banner "Frequency Shield" were some
low cost frequency jamming equipment marketed as "Frequency Control". Here is directly from the
AliExpress ad ---- "Module overview -- Used to generate a sweep frequency suppression signal in a
certain frequency band to shield and interfere with the equipment in the corresponding frequency band.
It is widely used in WiFi signal shielding, 433M signal, GPS positioning, UAV countermeasures and
other application scenarios. --- available for 315MHz, 300-400MHz, 433MHz, 840-960MHz, 1200-
1400MHz, GPS 1575MHz, 2400-2500MHz, 5160-5320MHz & 5725-5850MHz"
If we here in Boulder thought our 70cm RFI issue was bad for our W0BTV repeater, just imagine what
it will be like if enough bad guys start using this *^%%#*$ stuff from China which is so cheap and
readily purchased over the internet !
Disgusted ! -- de Jim, KH6HTV
========================================================================
TV Rptrs Rptr-147.doc ( 11/22/23, kh6htv) p. 11 of 12
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:
https://kh6htv.com/application-notes/
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: https://batc.org.uk/live/ 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: https://kh6htv.com/newsletter/
ATV HAM ADS -- 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.
DVB-T Receiver for Sale: I have a brand new Hi-Des model HV-110 that I don't plan
to use. It comes with everything shown - HV-110 receiver, software CD, power supply, video cable,
and remote control. I purchased it a few weeks ago after seeing a talk at Pacificon but decided I'm not
ready to get into this part of the hobby yet. I plugged it in to confirm it works (it does). Price is US$90
shipped. Contact me at chancekp@yahoo.com if you are interested. Kevin, KN6WKM
(editor's comment -- the new price from Hi-Des is $119, so you can save $29 buying it from Kevin)
===================================================
TV Rptrs Rptr-147.doc ( 11/22/23, kh6htv) p. 12 of 12
HV-320 DVB-T Modulator 70-7B Amplifier 70-9B or 23-11A Amplifier
Your NEW DVB-T 70cm or 23cm Transmitter
What is required to put a digital ATV signal on the air ? 1. Video source, such as a cam-corder camera 2. A
DVB-T modulator 3. A Linear RF Power Amplifier & 4. An Antenna. KH6HTV Video can supply you
with a "Turn-Key" DVB-T Transmitter. No building DIY, nor programming required, just "plug-n-play". The
transmitter would consist of a Hi-Des model HV-320B Modulator and one of the above Amplifiers. The
modulator would come pre-programmed to work on the amateur ATV channels. I am offering to purchase the
modulator for you, program it, and resell it to you at cost. The catch is you also need to purchase an amplifier
from me.
For base station, or repeater use, I offer the larger amplifier package shown on the right in the above photo. For
the 70cm band, it is my model 70-9B. It is a 70 Watt amplifier (FM/CW service) which puts out 10 Watts
average power in digital TV service. It operates from a +12Vdc supply and pulls 8 Amps. For the 23cm band,
it is my model 23-11A. It is a 30 Watt amplifier (FM/CW service) which puts out 4.5 Watts average power in
digital TV service. It operates from a +12Vdc supply and pulls 6.5 Amps.
For out in the field, portable ATV operations, we run on batteries. There conserving battery capacity is very
important. So we need to use equipment with much lower current requirements. The 70cm, model 70-7B
amplifier was designed specifically for these applications. It is the ideal choice if your local ARES group is
considering adding ATV capability to the services they offer to the public safety agencies. For example, the
Boulder, Colorado ARES group (BCARES) has 4 complete DVB-T portable pack sets, all using the 70-7B
amplifier. The 70-7B is a 25 Watt amplifier (FM/CW service) which puts out 3 Watts average power in digital
TV service. Operating from a 12Vdc battery it pulls 2.6 Amps at full power. The RF power can also be
lowered with a front panel rotary switch by -5dB & -10dB. The respective current draws are thus: high power
= 3 W @ 2.6 A, medium power = 1W @ 1.2A and low power = 300 mW @ 700 mA. www.kh6htv.com
If you are interested, contact KH6HTV for a detailed quote at 303-594-2547 or kh6htv@yahoo.com

https://kh6htv.files.wordpress.com/2023 ... tr-147.pdf
s58ru
 
Prispevkov: 1051
Pridružen: 28 Okt 2004, 21:07

Re: revija ATV

OdgovorNapisal/-a s58ru » 01 Dec 2023, 18:22

TV Rptrs Rptr-148.doc ( 11/28/23, kh6htv) p. 1 of 16
Boulder Amateur
Television Club
TV Repeater's
REPEATER
December, 2023
issue #148
BATVC web site: www.kh6htv.com
ATN web site: www.atn-tv.com
Jim Andrews, KH6HTV, editor - kh6htv@arrl.net www.kh6htv.com
(from K0DVB)
SPECIAL ISSUE on
DVB-T Digital Parameters
Jim, KH6HTV
Note: several figures used in this article came from K0DVB, Matt Holiday's slide show talk given as ATV training classes to members of the Boulder,
CO ARES (BCARES). https://k0dvb.org/ https://bouldercountyares.org/our-tool- ... mateur-tv/
TV Rptrs Rptr-148.doc ( 11/28/23, kh6htv) p. 2 of 16
In our previous issue, #148, we discussed some experiments to demonstrate the effects of adjusting the
various digital parameters for a DVB-T signal upon the ultimate weak signal capability of a receiver.
So just what are these parameters ?
I consider the "Bible" for DTV. ------ "Digital Video and
Audio Broadcasting Technology --- A Practical
Engineering Guide" by Walter Fischer (TV engineer at Rhode
& Schwartz, Munich, Germany). Springer, 3ed edition, 2010
Much of the material for this article comes from this book. I denote
this material using quotes.
SOURCE CODING--MEDIA CONFIGURATION:
Video Encoding: For DVB-T, we have a choice of two
methods, either MPEG2 or H.264.
"In 1992, MPEG-1 was created as the first standard for encoding
moving pictures accompanied by sound. The aim was to achieve a
picture quality close to that of VHS (352x288) at CD data rates (<
1.5 Mbit/s)." MPEG-2 then followed in 1996 with higher resolution,
better quality, and supported transmission, not just
data storage. Then in 2003 a still more improved
system was released. It goes by several names,
H.264, AVC (Advanced Video Coding) or MPEG-
4, part 10. "Compared with MPEG-2, H.264 is
more effective by a factor of 2 to 3 and thus allows
data rates which are lower by a factor of 2 to 3,
often even with improved picture quality."
Video Encoding Resolution: With Hi-Des
modulators, we have the ability to then select our
desired resolution. They range from a low of
360x480 to a hi-def high of 1920x1080 pixels. For
some other brands, this is not an option.
(from K0DVB)
Max. Bit Rate: For Hi-Des, this is a user selectable value, while for some other brands it is fixed.
It can never be set higher than a calculated theoretical maximum called the Modulation Data Rate.
Hi-Des recommends it never be set any higher than about 80% of the Modulation Data Rate. This is to
allow space for audio encoding and other over-heads. For very low RF band-widths, the percentage
should be set considerably lower than 80%.
TV Rptrs Rptr-148.doc ( 11/28/23, kh6htv) p. 3 of 16
Video Aspect Ratio: This is the ratio of the screen width to height. Older TVs used 4:3.
Newer wide screen TVs use 16:9.
Video Encoding Frame Rate: This is the number of video frames transmitted per second.
We ususally try to adhere to the old NTSC (30 fps) or PAL (25 fps) standards.
Video Encoding GOP Length: GOP stands
for Group of Pictures. Successive frames of
video are sent as various types of data. First there
is the "I" or "Key" frame. It sends all the data
required to create a complete picture in a frame.
Each GOP begins with this "I" frame. The "I" is
then followed by "B" and "P" frames which only
send partial data, mainly dealing with motion
compensated differences from the "I" frame. The
GOP length parameter determines how many video
frames are sent before starting over again with a
new "I" - Key frame. Typical GOP length values
are 30 or 60, i.e. every 1/2 second or full second.
(from K0DVB)
CHANNEL CODING -- TRANSMISSION CONFIGURATION:
Modulation: The choices for DVB-T are:
QPSK, 16QAM or 64QAM. QPSK stands for
Quadrature Phase Shift Keying. It is similar to FM
in that there is no change in the amplitude of the rf
signal, only shifting of 90, 180, 270 or 360 (0)
degrees of the phase. It is usually graphically
displayed as a Constellation diagram with I & Q
axis ( I = in phase, Q = quadrature, or 90 deg ).
QPSK is the simplest with 4 possible logic states
and 2 Bits/symbol. QAM stands for Quadrature
Amplitude Modulation. It starts out with QPSK,
but then adds discreate amplitude levels for higher
amounts of logic. 16QAM adds 2 more
amplitude levels of 25% and 75%. It is best
shown in the I/Q constellation drawing to the right.
It now has 16 logic states an 4 Bits/symbol.
64QAM adds even more amplitude levels with 64 ( from K0DVB)
logic states and 6 Bits/symbol. Using higher levels of QAM allows more data to be transferred within
a fixed band-width rf channel. There will be some compromises required however to be discussed
further. With the newer DVB-T2, they have added an even higher choice of 256QAM.
TV Rptrs Rptr-148.doc ( 11/28/23, kh6htv) p. 4 of 16
Is QAM better than QPSK in a noisy rf channel ?
What does this I/Q QAM picture tell you ? For
the same amount of added rf noise to each logic
state, we see that with 16QAM, the various logic
states now are interfering with each other.
We reported some experimental results in our last
ATV newsletter, issue #147 comparing these.
16QAM required a 6 dB stronger signal than QAM,
while 64QAM required a 14 dB stronger signal.
Clearly going to 256QAM with DVB-T2 would
require an even stronger rf signal with attendent
improvement in required S/N.
(from K0DVB)
# of Sub-Carriers: DVB-T uses a system called Coded Orthogonal Frequency Division Multiplex
or COFDM for short. Basically it means the data is split up and transmitted over many sub-carriers.
For DVB-T the choice is either 2K or 8K. Newer DVB-T2 adds more choices. For our USA
standard 6 MHz TV channels, the sub-carrier spacings are: 840 Hz (8K) or 3.35 kHz (2K).
"Due to multi-path reception, fading occurs which is frequency- and location-selective. In terrestrial
radio transmission, narrowband or wideband sinusoidal or impulse-type interferers must also be
expected which can adversely affect reception. Plus Doppler shift in mobile operations." --- "Single
carrier methods have a relatively high symbol rate, often within a range of more than 1 MS/s up to 30
MS/s. This leads to very short symbol periods of 1 μs and shorter (inverse of the symbol rate).
However, multi-path echo delays can easily be within a range of up to 50 μs or more in terrestrial
transmission rf channels. Such echoes would lead to inter-symbol interference between adjacent
symbols or even far distant symbols and render transmission more or less impossible. An obvious
trick would now be to make the symbol period as long as possible in order to minimize inter-symbol
interference and, in addition, pauses could be inserted between the symbols, so-called Guard intervals.
However, there is still the problem of the location- and frequency selective fading phenomena. If then
the information is not transmitted via a single carrier but is distributed over many, up to thousands of
subcarriers and a corresponding overall error protection is built in, the available channel bandwidth
remaining constant, individual carriers or carrier bands will be affected by the fading, but not all of
them. If, however, many thousands of subcarriers are used instead of one carrier, the symbol rate is
reduced by the factor of the number of subcarriers and the symbols are correspondingly lengthened
several thousand times from < 1 μs up to a millisecond. The fading problem is solved and, at the same
time, the problem of inter-symbol interference is also solved due to the longer symbols and the
appropriate pauses between them. It is now only necessary to see that the many adjacent carriers do
not interfere with one another, i.e. are orthogonal to one another. Hence COFDM."
For DVB-T, there is a choice of using either 2K or 8K sub-carriers. Thus "the symbol lengths are
either 250 μs (2K) or 1 ms (8K). The 2K mode has greater subcarrier spacing of about 4 kHz but the
symbol period is much shorter. Compared with the 8K mode with a subcarrier spacing of about 1 kHz,
TV Rptrs Rptr-148.doc ( 11/28/23, kh6htv) p. 5 of 16
it is much less susceptible to spreading in the frequency domain caused by doppler effects due to
mobile reception and multiple echoes but much more susceptible to greater echo delays caused by
doppler effects due to mobile reception and multiple echoes." DVB-T2 adds more choices of the
number of sub-carriers.
Actually not all of the many thousand sub-carriers are dedicated to carrying our A/V data. DVB-T
also contains: Inactive carriers with fixed positions, Contiuous Pilots with fixed position, Scattered
Pilots with changing positions and Transmission Parameter Signalling (TPS) carriers with fixed
positions. The TPS carriers represent virtually a fast information channel via which the transmitter
informs the receiver about the current transmission parameters. The Pilot Carriers are used in the
receiver for rf channel degradation effects estimation and subsequent correction to remove multi-path.
Guard Interval: The purpose of the guard interval is to introduce immunity to propagation
delays, echoes and reflections, to which digital data is normally very sensitive. In OFDM, the
beginning of each symbol is preceded by a Guard interval. As long as echoes fall within this interval,
they will not affect the receiver's ability to safely decode the actual data, as data is only interpreted
outside the guard interval. The guard interval is not left empty, but contains a fixed data pattern
which helps the receiver acquire sync lock. In DVB-T, the choices for Guard are: 1/32, 1/16, 1/8
and 1/4 of the data symbol length.
Forward Error Correction - Code Rate: The previous parameters discussed concerned how
the data was arranged in the COFDM signal to compensate for rf channel degradation. The Code Rate
deals with adding Forward Error Correction (FEC) to help the receiver decode corrupted data. In
DVB-T, the choices for Code Rate are: 7/8, 5/6, 3/4, 2/3 and 1/2. What this ratio means is how much
of a symbol is devoted to real video data and how much is error correction info. For example 5/6
means a video data symbol is split into 6 pieces with 5 being real video data and the last piece being
error correction data.
Channel Band-Width: The sizes of many other parameters are determined based upon how
much frequency is allocated to the actual rf channel. In the USA, the standard TV channel band-width
is 6 MHz. Standard TV channels vary from 5 to 8 MHz world-wide. 7 MHz in Europe being the
most common. With the transition from analog TV to digital TV, these channel band-widths were
usually retained. Radio amateurs have been recently experimenting with narrower band-widths. Hi-
Des DVB-T equipment supports band-widths down to 2 MHz. An actual DVB-T signal does not
occupy the entire channel allocated band-width. It is actually a bit narrower to allow some guard band
for the steep skirts of the digital signal to roll-off to an acceptable lower dB level. For 6 MHz BW,
DVB-T, the actual signal band-width is 5.71 MHz.
Modulation Data Rate: This is NOT a parameter which can be programmed by the user.
Instead it is a theoretical, calculated value based upon the selection of all of the above transmission
parameters. This is the number which should be consulted when setting the video encoding data rate.
As an example for: 6 MHz BW, QPSK, 8K sub-carriers, 5/6 Code Rate, and 1/16 Guard Interval, the
calculated Modulation Data Rate is 7.16 Mbps. Going from QPSK to 64QAM ups this to 21.96
Mbps.
TV Rptrs Rptr-148.doc ( 11/28/23, kh6htv) p. 6 of 16
AN-39 DVB-T Recommended Parameters -- This app. note was written in 2017,
but is still very relevant today. Therefore, I am re-printing it here in our ATV newsletter. It
discussed some lab bench tests comparing various digital parameters, much like we recently repeated
and reported in the last newsletter, issue #147. Of particular interest is the inclusion of some actual, in
the field, mobile tests which compared results using both analog FM-TV, analog NTSC VUSB-TV,
with DVB-T, and on both 70 cm and 23 cm bands.
Application Note
AN-39c
June, 2017
rev. Jan. 2021
rev. Nov. 2021
rev. Jan. 2023
DVB-T Recommended Parameters
Jim Andrews, KH6HTV
I am often asked what parameters are recommended for DVB-T, amateur, digital Television (DTV).
The commonly used modulators, such as the Hi-Des model HV-100EH, HV-310 or HV-320E, allow a
wide adjustment range in many of the parameters. The selection of the proper values can have a
dramatic impact on the system performance. The table below lists my recommendations.
Common Parameters: Media Configuration = HDMI input, H.264 Video Encoding, CBR Data
Rate Control, 29.97fps Frame Rate, 16:9 Aspect Ratio, 30 GOP Length, 0 B Frame Number,
MPEG2 Audio Encoding, 96Kbps Audio Encoding Rate, and HDMI HDCP = on
Transmission Configuration = 8K FFT, 1/16 Guard (sync) Interval
TS Info Configuration = PMT PID 0x640, Video PID 0x641, Audio PID 0x642, Service Name = your
station's call sign
PARAMETER Perfect
Channel
Normal
Channel
Poor
Channel
Weakest
Signal
Bandwidth 6 MHz 6 MHz 6 MHz 2 MHz
Modulation 16-QAM QPSK QPSK QPSK
Resolution 1080P 1080P 720P 480i
lines 1920x1080 1920x1080 1280x720 720x480
Forward Error
Correction
(Code Rate)
5/6 5/6 1/2 3/4
Bit Rate 11.5 Mbps 5.5 Mbps 3.5 Mbps 1.2 Mbps
Receiver
Sensitivity
-91dBm -96dBm -100dBm -103dBm
with Pre-Amp -94dBm -100dBm -104dBm -108dBm
TV Rptrs Rptr-148.doc ( 11/28/23, kh6htv) p. 7 of 16
RECEIVER SENSITIVITY: The values reported in the table for receiver performance were
measured at 423 MHz on a Hi-Des model HV-110, DVB-T receiver. The measurements were made in
a controlled lab environment on a well shielded, closed coaxial circuit, using an HV-100EH modulator
and calibrated coaxial fixed and step attenuators The modulator was located 75ft. away from the
receiver to minimize any leakage signals. Thus the only effect altering the transmission channel was a
progressively weaker, attenuated signal. There was no multi-path, RFI, etc. present to distort the
signal. The pre-amp values were measured using an ARR model P432VDG amplifier (0.5dB NF,
18dB gain). Adding the low noise, pre-amp in front of the Hi-Des receiver improved the sensitivity by
3 to 5dB.
Fig. 1 Transmission Configuration page of AVSender --- shown with recommended settings for
normal 1080P, 6 MHz BW, QPSK operation -- note: a custom channel table was used.
TRANSMISSION PARAMETERS: The parameters of Bandwidth, FFT, FEC and Guard
Interval are extremely important in determining how well your TV signal will propagate and be
decoded at the receiver under real world, multi-path conditions. These are set on the Transmission
Configuration page of AVSender, Fig. 1. AVSender is the Windows computer program supplied by Hi-
Des for setting the modulator's digital parameters. The normal bandwidth used is 6 MHz in the USA,
which is the same as used by commercial broadcast TV stations. For extremely weak signal
performance, going to the lowest possible bandwidth of 2 MHz with lower, 480i, standard definition
resolution buys several dB in receiver sensitivity. The Constellation parameter selects the modulation
method of either QPSK, 16QAM or 64QAM. The best video performance (in very strong signal
conditions) is obtained using 64QAM and the highest possible bit rate. For weak signal, amateur
useage, QPSK is recommended. Very acceptable, high-definition, video performance with normal
scenes is obtained using QPSK. The Guard Interval is used to synchronize the receiver. It is the same
as sync pulses used in the old analog NTSC system. The Guard ratio determines how much of the
total data frame is devoted to "sync". The Code Ratio, also called FEC or Forward Error Correction
ratio determines how much data is devoted to error correction, versus the true live video data. 5/6 FEC
TV Rptrs Rptr-148.doc ( 11/28/23, kh6htv) p. 8 of 16
means for every 5 bits of real data, one extra bit is added for error correction. The FFT determines
how many subcarriers are used within the channel bandwidth. The choice is either 2000 or 8000. (2K
or 8K). I selected using an FFT of 8K based upon the recommendation in reference [1] which stated
"An 8K system allows reception with longer multi-path echos." 2K is supposed to be a better choice
for Doppler shift corrections for mobile operations. I have found that 8K works fine with mobile
doppler shift at speeds of at least 75 mph.
Fig. 2 Media Configuration page of AVSender --- shown with recommended settings for normal
1080P, 6 MHz BW, QPSK operation
MEDIA PARAMETERS: Another key parameter is the encoding data rate, called "Max Bit Rate."
This is found on the Media Configuration page of AVSender, Fig. 2. To follow rapidly changing
scenes, the highest possible data rate should be used. The max. theoretical possible data rate is a
function of Bandwidth, modulation type, FEC and Guard Interval. Ref [2] tabulates all of the various
possible options. AVSender also displays the theoretical maximum for any setting. It is on the
Transmission page, Fig. 1, and called "Modulation Data Rate". It is grayed out indicating that you can
not alter it. For a 6 MHz bandwidth, the theoretical maximum is 23.75Mbps for 64QAM with 7/8 FEC
and 1/32 Guard Interval. For QPSK the maximum is a much lower 7.92Mbps with 7/8 FEC & 1/32
Guard.
The older Hi-Des HV-100EH will not operate above 16 Mbps. Trying to set any data rate too high, the
Hi-Des HV-100EH defaults back to 8 Mbps. Thus there is not much to be gained by using 64QAM
over 16QAM with the HV-100. The newer HV-320E does work with 64QAM at the highest data rate
(suggest limit to 18 Mbps).
Caution: Operation at or near the theoretical maximum sometimes gave unacceptable breakups the
picture. In their instruction manual, Hi-Des recommends that the "Max Bit Rate" be set no higher than
TV Rptrs Rptr-148.doc ( 11/28/23, kh6htv) p. 9 of 16
80% of the theoretical max. "Modulation Data Rate." The values listed in the above table are set
approximately at 80%.
Another important parameter to be set is that of HDMI-HDCP. The HDMI protocol allows for
motion picture copyright security to be implemented. Normally this prevents the use of certain HDMI
equipment with others if copyrighted media would be compromised. This means that under some
circumstances a video source such as a DVD player can only be connected to a video monitor and not a
transmitter. If this parameter is set to OFF, you will not be able to connect a DVD player to your Hi-
Des modulator. It will not accept the source and give you instead a screen with the test "No Input
Video". It will only accept a TV camera input. To avoid this situation, you should thus set this HDCP
parameter to ON. This does not mean it is thus OK or legal as an amateur to transmit copyrighted
movies. But we may want to transmit our own DVD home movies, such as family events or travels. It
is legal for us to do this.
Fig. 3 TS Info configuration page of AVSender
TS INFO PARAMETERS: Don't change most of the parameters on this page, Fig. 3. The
PIDs (Packet Identifiers) shown are the normal factory presets and normally shouldn't be changed. All
DTV amateurs in your local area should use the same PIDs. If the PIDs of different stations do not
match, the Hi-Des receivers will lock up when receiving a signal with different PIDs than those it was
originally trained with.
Do however change the Service Name. Enter here your own stations's call sign. It will then be
transmitted automaticaly with the data header and make your station IDing automatic to comply with
FCC ID regulations.
NORMAL CHANNEL: Under normal conditions, to obtain the highest video definition possible
of 1080P, a 6 MHz bandwidth is used. Most amateur operations are done with far lower rf power
TV Rptrs Rptr-148.doc ( 11/28/23, kh6htv) p. 10 of 16
levels than commercial broadcast ( watts vs. kilowatts ! ). Thus, the preferred modulation method is
QPSK. QPSK gives considerable improvement in receiver sensitivity (-96dBm vs. -91dBm for
16QAM and -82dBm for 64QAM). 8K FFT was chosen to handle longer multi-path echos. I chose to
use the factory presets of 5/6 FEC and 1/16 Guard Interval. Jim White, NC0JW, has confirmed that
they are the same settings which CBS found in early DTV propagation experiments to work best in
most situations [3]. These settings have been found to give very acceptable video performance for
most all, but the very, fastest moving sports scenes.
POOR CHANNEL: For marginal channel conditions, with either weak signals and/or severe
multipath(s), operation with the "Normal" parameters will be impossible. Oftentimes, perfect P5
video/audio can again be achieved by lowering the video resolution and using much more aggressive
forward error correction. High definition, 720P, performance can still be achieved with very good
picture quality. Using the much more aggressive FEC than for the Normal channel resulted in a 4dB
improvement in receiver sensitivity for a multi-path free, closed circuit channel. Even better
sensitivity improvements have been observed in real world, over the air conditions. A test run by
Colin, WA2YUN, and Jim, KH6HTV on 23cm, DVB-T using loop yaggi antennas on a clear, line of
sight, 5.6 mile path showed an impressive, 10dB improvement in weak signal reception using the 720P,
1/2 FEC over the 1080P, 5/6 FEC parameters.
2 MHz BANDWIDTH: In many parts of the USA, in particular large metro areas, there is too
much other RF activity on the amateur 70 cm band to allow use of the full, broadcast standard, 6 MHz
bandwidth. The Hi-Des modulators and receivers are capable of operating at much lower bandwidths,
down to 2 MHz. Hi-definition, 1080P resolution does not work well at 2 MHz BW, QPSK. However,
excellent video performance with standard definition, 480i is possible at 2 MHz BW, even using very
aggressive FEC. Going to a lower bandwidth also buys us a considerable increase in receiver
sensitivity (-108dBm, 0.9μV with a pre-amp). High definition, 720P, is possible at 2 MHz BW
however using 16QAM or 64QAM.
DVB-T RECEIVERS: Fortunately, the available receivers are smart and do not need to be
retrained when most of the transmitter's digital parameters are changed, even on the fly. As long as the
center frequency, bandwidth and PIDs remain unchanged, the receiver will automatically track changes
in parameters such as Constellation, FEC, Guard ratio, FFT, etc.
TV Rptrs Rptr-148.doc ( 11/28/23, kh6htv) p. 11 of 16
Fig. 4 TV Repeater Field Survey Route through city of Boulder & Boulder Valley
FIELD TESTS: In May and June, 2017, several Boulder, Colorado ATV amateurs did a series of
field tests to compare various TV modulation methods, including DVB-T. Hams participating were:
Don, N0YE, Colin, WA2YUN, Jack, K0HEH and Jim, KH6HTV. The Boulder TV repeater, W0BCR,
was used. It is capable of receiving on both 23cm and 70cm bands. On 23cm, it receives either 6
MHz bandwidth, DVB-T, or 4 MHz deviation FM-TV. On 70cm, it receives either 6 MHz bandwidth,
DVB-T, or 6 MHz bandwidth, NTSC, VUSB-TV. The repeater's ability to receive TV signals on all of
these modes/bands was tested in controlled experiments. For DVB-T, the 1080P, 5/6 FEC and 720P,
1/2 FEC modulation parameters were tested and compared.
The first tests were performed by driving a mobile TV transmitter on a fixed, 30 mile route, Fig. 4. A
camera was set up on a tripod in the passenger seat looking out the front windshield giving a live view
of the current location of the transmitter. A TV receiver at the qth of KH6HTV was monitoring the
relayed video from the TV repeater and it was recorded permanently on a DVD for later review and
analysis. Also during some of the tests, N0YE and WA2YUN monitored the TV repeater's relayed
images.
For the tests, the mobile transmitters and antennas used were very comparable for both bands. The
digital, DVB-T, transmitters and the 23cm FM-TV transmitter all put out about 3 Watts (+35dBm). The
70cm, VUSB-TV transmitter put out 10 Watts (PEP). The mobile transmit antenna was a Diamond,
TV Rptrs Rptr-148.doc ( 11/28/23, kh6htv) p. 12 of 16
tri-band, model NR-2000NA with 9 dBi gain on 70 cm and 7 dBi on 23 cm. The TV repeater's receive
antenna, a Diamond X6000A, had essentially the same gain of +7 dBi on both 70 cm and 23 cm.
There was a 14 dB difference between 23cm vs. 70cm tests, which consisted of the 10 dB extra path
loss, 2 dB difference in transmitter antenna gains and about 2 dB additional coax feedline loss.
Fig. 4 shows the route driven for each of the six tests in the city of Boulder and the surrounding
Boulder valley. This was almost a 30 mile route and typically took about 1 3/4 hours to traverse. The
route chosen included rural, residential, urban canyons (among tall buildings), light industrial, open
rolling hill prairie, high ridges, wooded areas, flat highways for high speeds (55mph), etc. It included
several areas where BCARES has operated in the past for major police operations including the
University of Colorado campus, Uni-Hill district, downtown Boulder, etc. Also included were the
QTHs of several active ATV amateurs. The farthest distance tested from the repeater was about 6
miles.
CONCLUSION: In summary, the following list prioritizes the overall performance of the six,
various modes/bands tested from best to worse.
1. 70cm, digital, DVB-T, 720P resolution, 1/2 FEC aggressive digital parameters.
2. 70cm, digital, DVB-T, 1080P resolution, 5/6 FEC, normal digital parameters
3. 70cm, analog, VUSB-T, 480i resolution
4. 23cm, digital, DVB-T, 720P resolution, 1/2 FEC, aggressive digital parameters
5. 23cm, analog, FM-TV, 480i resolution
6. 23cm, digital, DVB-T, 1080P resolution, 5/6 FEC, normal digital parameters.
Fig. 5 below shows an example of the video images received and recorded on DVDs for later review.
This example was retrieved from three separate field test runs at the same identical location, but with
different different modulation methods of FM, VUSB and DVB-T. At this particular location, the
transmitter vehicle was shielded from the repeater by the highway overpass and berms.
Clearly, the best performance was found using DVB-T on the 70cm band with a lower 720P
resolution and the best possible, most aggressive, Forward Error Correction (FEC) of 1/2. Perfect
P5 reception by the repeater was achieved from well over 90% of the total 30 mile route tested.
None of the other modes/bands came anywhere close to this performance. The 23cm coverage was
particularly poor with coverage from much less than 30% of the areas tested.
TV Rptrs Rptr-148.doc ( 11/28/23, kh6htv) p. 13 of 16
Fig. 5a 23cm DVB-T with aggresive coding of 720P and 1/2 FEC
Fig. 5b 23cm FM-TV, 4 MHz deviation, 480i standard definition
TV Rptrs Rptr-148.doc ( 11/28/23, kh6htv) p. 14 of 16
Fig. 5c 70cm VUSB-TV, normal analog NTSC standard definition
Fig. 6 Radio Mobile RF path prediction from DIA site to TV repeater
TV Rptrs Rptr-148.doc ( 11/28/23, kh6htv) p. 15 of 16
DIA TESTS: In June, N0YE and K0HEH drove out to the Denver International Airport (DIA) to
perform repeater coverage tests from a remote, fringe area where BCARES might be called upon in the
future for an airplane crash disaster. Fig. 6 shows the computer predicted, 70cm, rf path profile for the
tests from DIA to the Boulder TV repeater, using the on-line program Radio Mobile [4]. The path was
clear, unobstructed, line-of-sight over rolling prairie, but over a long distance of 32 1/2 miles. The
70cm predicted path margin was 13dB. They tested both 23cm and 70cm bands and all modes. For
DVB-T, they only used 720P, 1/2 FEC. They used yaggi antennas (11dBi on 70cm & 18dBi on 23cm)
on a telescoping mast. They were able to put perfect P5 pictures (except P3+ for 70cm, VUSB-TV)
into the repeater from antenna heights of at least 10ft. They were unsuccessful with a mag. mount
mobile, tri-band,NR-2000NA antenna.
REFERENCES:
1. "Digital TV - DVB-T", h ttp://digitaltvbooks.com/cofdm.pdf
2. "Digital Video and Audio Broadcasting Technology - A Practical Engineering Guide", W.
Fischer, Springer-Verlag, Berlin & Heidelburg, DE, 3ed Edition, 2010, ISBN 978-3-642-11611-7
3. Jim White, NC0JW, retired KCBS rf broadcast engineer, private conversation 10 July 2014.
4. "TV Propagation", Jim Andrews, KH6HTV Video Application Note, AN-33a, Oct. 2016.
Note: Revision "A", Jan. 2021 -- only change made was lowering the bit rates in table 1, page 1 to
agree with Hi-Des recommendation they be no higher than 80% of max.
Revision "B", Nov. 2021 -- added comments about HDMI-HDCP.
Revision C, Jan. 2023 -- added info about HV-320E, corrected table I for weak signal FEC from 1/2 to
3/4
============================================================
FEEB-BACK:
Digital Parameters: Thanks for sharing your test results with the Hi-Des gear. I may do some more
“tweaking” of our parameters based on your results. As some one said, “What a difference a dB can
make.” 73/Happy Thanksgiving, Mel, K0PFX, St. Louis, MO
Nostalgia: Another excellent newsletter Jim! I especially enjoyed your reminisces about the early
days of fiber optic communications. I think that was about the time I was pushing modulation format
up to 90 state QPR and stuffing 45 Mb/s (T3) data into a 10 MHz FCC allocation at 6 GHz. It was sure
frustrating back then but thinking back now it was also a lot of fun.
Aloha, Alan AD6E / KH6TU, Maui, Hawaii
Laser Comms: Jim, I really love this newsletter. Did I ever mention that I've also been working with
LASER Diode transmitter/receivers there in Panama City, Florida ? I like that BATC and So Cal are
also doing it. One of the things I'd like to do now that I'm up and running on AREDN is to be able to
use LASER for short range field deployments for disaster sites and events. This would be the ticket for
our Mesh Chat, PBX systems, our mailbox servers "WINLINK" and for live streaming or video
TV Rptrs Rptr-148.doc ( 11/28/23, kh6htv) p. 16 of 16
cameras. I've been at it for right at 5 years and I get a good amount of pointers and assistance from
Mike Collis in LA. Didn't know if you mentioned my name, call sign and location would help to bring
more interest in this High Speed communications. Feel free to mention me in any article or news letter.
Hope your Thanksgiving was a great one.
73 de Wolfgang, KV4ATV, Panama City, Forida
==================
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:
https://kh6htv.com/application-notes/
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: https://batc.org.uk/live/ 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: https://kh6htv.com/newsletter/
ATV HAM ADS -- 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

https://kh6htv.files.wordpress.com/2023 ... tr-148.pdf
s58ru
 
Prispevkov: 1051
Pridružen: 28 Okt 2004, 21:07

Re: revija ATV

OdgovorNapisal/-a s58ru » 09 Dec 2023, 23:31

TV Rptrs Rptr-149.doc ( 12/9/23, kh6htv) p. 1 of 11
Boulder Amateur
Television Club
TV Repeater's
REPEATER
December, 2023
2ed edition, issue #149
BATVC web site: www.kh6htv.com
ATN web site: www.atn-tv.com
Jim Andrews, KH6HTV, editor - kh6htv@arrl.net www.kh6htv.com
A NEW ATV NEWSLETTER !
The following article on A/V sync is reprinted with permission from SLATS
We have all experienced the video lagging the audio and find it can
be quite frustrating when a speaker’s lips are not in sync with their
voice. What causes this? Can it be avoided in DATV
transmissions? Let’s take a look at this problem.
First of all, we are not alone with this “sync” problem. As you may
have noticed while watching commercial broadcasting TV. It happens often. Poor synchronization is
experienced by just about everyone in the industry. In the recording industry a sync difference of more
TV Rptrs Rptr-149.doc ( 12/9/23, kh6htv) p. 2 of 11
than 20ms is a problem for them. Very poor “lip sync” can be really annoying. It doesn’t take much
delay to notice it. A couple hundred ms (milliseconds) lag in the video is noticeable. Longer delays may
make you want to look the other way while someone is talking. Broadcasters have soft-ware and
hardware tools that delay the audio in an effort to keep the audio in sync with the vid-eo. In hardware
you will find what are called “Audio Delay” boxes and “Lip Sync correctors.” Any delay must avoid
affecting the pitch of the audio too.
So, what does this all mean for us as ATV amateurs? Is there something we can do to improve the A/V
sync in our ATV signal? Maybe. HIDes has “Low Latency” firmware for some of their receiver/
transmitters. This might help with the lip sync but it is really for reducing overall A/V latency. To use
this firmware everyone must have the same model of transmitter and receiver. Currently, we all don’t. I
have not tried the firmware with the repeater’s HV-110 receiver. The repeater transmitter is a HV-200
which does not have any receiver low latency compatibility. Changing to a HV-320 would be possible
but the repeater really needs the HV-200’s loop through HDMI port. I don’t believe it would be worth
the effort and cost to consider this right now.
What else could be explored? --- The video requires a lot of processing for MPEG/H.264 compression
and FEC. This causes overall latency and video delay longer than the audio. First, at your transmitter
the video must be pro-cessed, then sent out OTA to the repeater’s receiver where it is processed and on
to the repeat-er’s transmitter where it must be processed again. Finally, at your receiver the video must
be processed yet again! And wow, what happens when we convert the transmitter’s HDMI output to IP
(internet protocol) streaming? Oh, now we can have at best 6-7 seconds of delay and up to 10 seconds
or more depending on the network not to even mention the lip sync problem. The internet delay is not
as bad as it may appear unless you are on 2 meters Talk-Back with zero delay audio talking about a
video that is being transmitted over the repeater. However, there is a way to get around some of this
problem. You could watch the IP streaming with VLC and then you’ll see when to sync your 2m audio
with the video.
The delay will seem long but it helps to avoid frustrating the viewer! Your internet latency may be
different than others, but anything to minimize the viewer’s frustration is worth the effort. This really
isn’t a fix for the A/V sync problem but rather something you should be aware anytime you are running
a video and talking about it on 2 meters. I failed to do this recently with a PowerPoint presentation and
was kindly reminded by a viewer of the latency!
Some TV sets (LG, SONY, Samsung) have a lip sync delay setting. It may be configured as Auto or
have a manual adjustment. If you are using a TV (vs a PC monitor), check to see if it has lip sync delay
correction. Maybe it could make a difference for DATV. Is there PC software that works with a sound
card to delay the audio for our application? Probably. This might be worth a few Google searches to
find out. Let me know if you find this as a possible solution. There is a lot of info about lip sync and
latency on the internet.
From our friends at B&H Photo and Video in NYC you will find an “A/V Lip-Sync Corrector” made
by SESCOM that adjusts the delay of the audio up to 300ms. Adding a delay in-line with the repeater’s
HDMI audio might help the lip sync problem. Would this be would be enough delay? I don’t know.
The SESCOM lip sync corrector is not an HDMI device. Rather, it is an analog one with RCA I/O
jacks. A quick Google search did not find a lip sync corrector for embedded HDMI audio. There
TV Rptrs Rptr-149.doc ( 12/9/23, kh6htv) p. 3 of 11
probably is one, but the cost could be prohibitive. What could be tried is a HDMI audio “Extractor” and
pass the output of it’s audio into the SESCOM and then into HDMI “Inserter.” Any audio passing from
the receiver (your input into the repeater) to the repeater transmitter would then be delayed. Caution
must be given here too. An HDMI signal can be degraded causing loss of sync due to the overall cable
length, cable bandwidth /adapters and any device added in-line. Keep this in mind too when adding
HDMI cables/switches/a DVR in your ATV station. General rule-of-the-thumb for HDMI cables is “the
larger the diameter the less loss.”
As you can see, I am looking for some way to add a delay into the audio line in an effort to reduce the
lip sync problem. Maybe there is an easy fix for this that I have missed. Perhaps, you may have an idea
I can try. If so, please let me know.
73 de Mel, K0PFX, St. Louis, MO
Mel at Pacificon-2023 Mel's Ham Shack
========================================================================
Velcro... The Solution to Everything! Simple Off-the-Shelf
Build of a Portable A5 Receive configuration using a 5
Inch Monitor/Demodulator, Preamp and Power Supply
Dave, AH2AR
Provided below are four photos that shows the "Velcro method" for configuring a handy self-contained
A5 (analog NTSC, ATV) demodulator/battery pack/ Marshall monitor/pre-amp/power supply/ and a
Lucite radio stand. Believe it or not, the configuration went together using Velco cut-outs that allows
for a clean and extremely secure approach that actually works great and this solution ensures a nice
form, fit and function. I have used this approach for other portable equipment builds for DVB-T with
surprisingly good results. The trick to this approach is to cut the Velcro out to conform to the mating
surfaces, because the more surface area employed, the more secure the hold will be.
TV Rptrs Rptr-149.doc ( 12/9/23, kh6htv) p. 4 of 11
AH2AR's new "To Go" analog, NTSC, ATV receiver and monitor
=========================================================================
STEM students working on CubeSat Bench Testing
Update: SDATV Project 2023 CubeSat
Greetings to all,
1-Our 2023 CubeSat project that had been planned in early spring of 2022 is coming along very well as
announced by its project manager Brian Copeland and his team including our STEM helpers. Funded
by the National Science Foundation and the support of the component supplier https://www.aacclyde.
space/.
2-My part is systems integration and testing, it's a 3U structure with a PC/104 form factor and a system
bus allowing modules to easily be stacked and routed.
3- It will be using the S-Band for tracking, telemetry and control {Module 2} out of six. I will be
working on Module 6 {camera/tranmitter}.
-- More updates to follow --
73 de Mario, KD6ILO, San Diego DATV Society
========================================================================
TV Rptrs Rptr-149.doc ( 12/9/23, kh6htv) p. 5 of 11
ATV from High Altitude Balloons - contd.
We recently got this inquiry via the DATV users group from a ham in British Columbia, Canada. -----
I just joined the group in hope some members might have some ideas for our project. We are launching
our second hydrogen balloon with cross-band repeater, and APRS on it in the new year. It goes to
100,000 feet before descending by parachute... total time of flight around 3 hours. We are thinking to
add a camera and possibly would like to send a photo to the ground every x seconds (much determined
by battery power available). Is there anything in the amateur tv world that might help without breaking
the bank? If not, any other ideas from the consumer market? Here is the URL link to our balloon
group: https://www.ve7nfr.com/pico-balloons.html
Thx, 73, Adrian VE7NZ
There were several replies for others in the users group. We felt they were worth while passing on.
Roger - VK5YYY replied -- "Have a look at this Adrian https://www.areg.org.au/archives/category/horus-datv "
Jim - G7NTG replied -- "Why not use a drone camera at 5665 MHz ?"
Dave - G8GKQ replied -- "Hi Adrian -- We have been unable to do fast-scan ATV from a balloon in
the UK due to licence restrictions, but it sounds like you are thinking of what we know of as SSDV
(Slow Scan Digital Video). There is lots of info here: https://ukhas.org.uk/doku.php?id=guides:ssdv .
I’m sure that you will find the rest of the Wiki useful as well. There is a group in the Netherlands that
does an annual launch of a balloon with fast scan digital ATV, but you probably would want to get
some experience with SSDV first."
Noel- G8GTZ also replied -- "The UK High Altitude Ballooning (HAB) community has been doing
this for some time using a system called SSDV. https://ukhas.org.uk/doku.php?id=guides:ssdv
Your editor, KH6HTV, also sent Adrian a lengthy email reply including references to all of the articles
we published here in this newsletter last spring on the subject. They included issues #s 124, 125, 126,
127, 128 & 135.
=========================================================================
The above URL link to www.areg.org.au is very interesting. It is very good documentation of a
balloon flight in 2021 which included live video using DVB-S on the 70 cm band.
TV Rptrs Rptr-149.doc ( 12/9/23, kh6htv) p. 6 of 11
Here are a few key details. We recommend you look at the complete web site for full details.
Balloon Payload
Payload Interior Guts 70cm Tracking Antennas
The DVB-S payload was the primary experiment on this flight, and developed by Mark, VK5QI, and
Peter, VK5KX. The payload utilised a Raspberry Pi Zero W to capture and compress video (using
F5OEO‘s DVB-S encoder and natsfr’s LimeSDR Gateware – this project would not have been possible
without their work – thanks!). This was then modulated as a 70cm (445MHz) DVB-S transmission
using a LimeSDR Mini. The signal was further amplified to ~800mW using a LDMOS-based power
amplifier. The overall power dissipation in the payload was ~6 watts, so a heat-spreading and heatsinking
system was built by Peter, including custom-milled interface plates for the LimeSDR. The
final DVB-S parameters used for the flight were: Frequency = 445.0 MHz, Mode = DVB-S,
Modulation = QPSK at 1 Msps, Forward Error Correction = 1/2 and Video Resolution = 720 x 404.
Last video image from space before balloon burst
=========================================================================
Mid-West ATV Nets: DARA/ATCO/ATN ATV NET Meeting time is 8 pm on
Wednesday evenings. the MidWest ATV DX group meets daily both weekdays and weekends at
7:30 am in the morning. Times are Eastern Standard Time. Both nets meet on the Zoom website
with a common conference log-in number of https://www.zoom.us/j/9670918666 For further info
on these nets, contact Dave, AH2AR.
TV Rptrs Rptr-149.doc ( 12/9/23, kh6htv) p. 7 of 11
BCARES ATV Equipment Update
Allen, K0ARK, reports that he has just finished re-packaging all four of the BCARES portable ATV
pac-sets in new hard cases. Each pac-set is a complete 70cm, DVB-T, 3 Watt transmitter. It contains
a Hi-Des HV-100 Modulator, a KH6HTV model 70-9B rf power amplifier, a Sony hi-def Camcorder, a
12 Amp-hr LiFePO4 battery, battery monitor and 70cm whip antenna. It is all internally pre-wired and
ready to go as a "Plug-n-Play" Allen then reused the old, orange hard cases previously used for the
camcorders to carry some other accessories. They include: camera tripod mounting plate for both
camcorder & antenna, HDMI cable, camera power cable, antenna coax cable, extra camera battery &
charger.
With four complete pac-sets, BCARES is capable of putting on the air simultaneously, four seperate
camera images. For this we use all four available, 70 cm, 6 MHz, ATV channels 57, 58, 59 & 60
(423, 429, 435 & 441 MHz). There have been some BCARES emergency operations in the past
when all four were required. With DVB-T, we have found it possible to work well without co-channel
RFI interference using all four adjacent channels. In the old days of NTSC, analog ATV co-channel
operation was always a challenge, even using very good inter-digital band-pass filters. Many times
then our received video images included bleed-over of TV signals from adjacent channels. These
new DATV pac-sets are stored in the BCARES equipment cache for 24/7 access in the Boulder County
911 Communications Center & EOC. Also see previous Oct. 2023 issue #143, p. 7
Allen has already had some inquires from other local hams asking if he would consider building an
ATV pac-set for them. Allen says "Yes". So, if you are interested, contact Allen directly. His
contact info is on www.qrz.com
========================================================================
Ham Radio Trivia: Did you know that one of the world's largest electronic component
distruibutors started out simply as a ham radio hobby business ? The company DigiKey started 50
years ago simply selling a kit of parts to build a digital electronic Morse code keyer for radio amateurs.
TV Rptrs Rptr-149.doc ( 12/9/23, kh6htv) p. 8 of 11
Hence the name DigiKey. It was founded in 1972 by Ron Stordahl, AE5E in Thief River Falls,
Minnesota. The company is still headquartered there. The company now has over 3 million sq.ft. of
facilities, 5000 employees, 15 million products and $5 billion in annual sales.
=========================================================================
NEW Antenna & Pre-
Amp Supplier Found !
Our super inter-net sleuth, Colin, WA2YUN, has made yet another find of relevance to us ATV hams.
He has discovered the company "Antennas-Amplifiers" in Serbia. ( www.antennas-amplifiers.com )
We suggest you check out their very interesting product offerings on their web site.
Colin was particularly interested in a dual-band, 70
cm/23 cm, Yagi antenna he found on their web site.
He was so interested that he ordered one for
evaluation. It is their model 70cm23WB11 and
sells for 159 € + shipping. Colin said it cost him
overall about $250. Colin brought the antenna to
the weekly Boulder, CO ham breakfast as a "shown-
tell" recently. We all found it to be an extremely
well built, very rugged antenna. Key specs. are:
Gain = 8.1dBi (70cm) & 11.4dBi (23cm), 4
elements on 70cm and 11 elements on 23cm, boom
length = 49 cm. The web site shows very complete
documentation with measurements perfomed on lab grade, quality test instrumentation. We will be
anxiously awaiting to hear the results of Colin's technical evaluation of the antenna.
=========================================================================
Dayton, Ohio - ATV News
The DARA ATV Repeater will be down while NEW equipmen
racks are installed
Bruce K8FIX, Doc, KE8DOC, and Dave, AH2AR, worked last
Sunday to remove all of the equipment from the DARA ATV
Repeater cabinets. The job took about four hours, and I am
guessing that the system will likely be down for six to eight weeks
or so. Taking this equipment removal job on during the holidays
makes for a busy month! The new racks will be installed and the
real job starts once the hardline and other electricals are configured
for the new installation.
TV Rptrs Rptr-149.doc ( 12/9/23, kh6htv) p. 9 of 11
Digital Parameters FEED-BACK:
Mike, WA6SVT -- "Thank you Jim for a wonderful newsletter! I learned a few new things from your
DVB-T school of how it all works. Of importance for me was the DHCP in the Hi-Des media
programming."
Chris, K0CJG -- "Thanks Jim. I now understand better how the various parameters affect
performance against different types of interference. Nothing in the standard encoding seems to
specifically tackle the QRM we see frequently on 70cm due to narrow band coherent signals."
Larry, N8GGG -- "I agree with Chris- though I've known some of this for quite some time, there's a
LOT I didn't know, and I'd never before seen it put together and explained so well. Lots of things are
much more clear now. Beautiful job! Thanks Jim"
Don, N0YE -- "Jim - Thank for these details. It will take time to digest all of the data."
Pete, WB2DVS -- "Jim - Thanks for putting all of this information in one place. Great issue!"
=========================================================================
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:
https://kh6htv.com/application-notes/
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: https://batc.org.uk/live/ 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: https://kh6htv.com/newsletter/
ATV HAM ADS -- 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-149.doc ( 12/9/23, kh6htv) p. 10 of 11
Hi --- It took a lot of work but in the end I'm happy to have saved at least part of the OE7forum pages
for you. Let’s keep blogging https://oe7dbh.blogspot.com I will continue to try to describe and test
all of HiDes' innovations that are important for amateur radio here, as well as my own projects.
I would also like to take this opportunity to wish you a happy Holiday, a Merry Christmas and a healthy
successful New 2024.
Vy 73 de OE7DBH, Darko
=========================================================================
Plus lots of other goodies - for
sale & to give away !
ICOM ID-1 data, D-Star & FM,
1.2GHz Transceiver
Marconi 6970 RF Power Meter
=========================================================================
KH6HTV Video annouces the introduction of a NEW product, the model
23-12, 23cm RF Linear Power Amplifier. Up until now, there has really only
been one choice for most ATV hams of an RF power amplifier for the 23cm band.
It has been the model 23-11A, or other similar amps. It's key DATV specs. were:
RF Power Out = 4.5 Watts (DTV service)
DC power required = 6.9 Amps at 13.8Vdc = 95 Watts, i.e. 5% efficiency
The new model 23-12 offers lower RF power, but is considerably more efficient. It's
key specs. are:
RF Power Out = 2.0 Watts (DTV service)
DC power required = 1.1 Amps at 13.8Vdc = 15 Watts, i.e. 13% efficiency
Thus, the new 23-12 now makes it possible to go portable out in the field with a
reasonable size battery. As such, it should be an ideal solution for ARES groups
wanting to do DATV on the 23 cm band. It is similar in performance to the
KH6HTV model 70-7B, 70 cm amplifier which is packaged in the same enclosure.
TV Rptrs Rptr-149.doc ( 12/9/23, kh6htv) p. 11 of 11
Model 23-12
23 cm, 43 dB, 13/7/2 Watt
RF LINEAR
POWER AMPLIFIER
The KH6HTV-VIDEO Model 23-12, RF Power Amplifier is for use in the amateur radio 23 cm
band. It is a Class A-B amplifier designed for linear service. It can be used to produce an 8
Watt (pep), analog TV or SSB signal. It can also produce a 2 Watt, high-definition (1080P),
digital TV (DTV) signal. With it's low DC current draw of only 1.1 Amps at 13.8 Vdc, it is ideal
for in the field battery operations, such as for ARES emergency operations.
PARAMETER Typical Performance Notes
Output Power (Digital TV) 2 Watts, +33dBm average power
Output Power (analog TVor SSB) 7 Watts PEP, +38 dBm peak power on sync tips
Output Power (FM, CW) 13 Watts, +41dBm saturated ouput
Output Power ( -1dB comp) 9 Watts, +39.5dBm
RF Power Amplifier Gain 43 dB, nominal
Amplifier Gain Flatness ± 1 dB 1240 - 1300 MHz
Amplifier Max Input Power 20 mW, +13 dBm
Spectrum Regrowth (Digital TV) -30 dB at +33dBm (2 Watts) -35dB at 1W, -40dB at 1/2W
LSB Rejection (analog VUSB) better than -20dB at 7 W peak sync
Duty Cycle 100 % heat sink & cooling fan included
DC Supply Voltage 13.8 Vdc 10 to 15 Vdc
DC Current 1.1 Amps (2W DTV), 0.5A idle @ 13.8Vdc
RF Connectors SMA input & N output
Dimensions & Weight 4.2" x 3.5" x 7.4" 1.5 lbs
Accessories Included instruction manual, test report, DC power cable & 12" SMA cable
KH6HTV-VIDEO Boulder, CO USA www.kh6htv.com kh6htv@arrl.net 303-594-2547
NOTICE: This linear amplifier is not FCC type accepted. Therefore, the use of this amplifier is
only legal in the USA, amateur radio, 23 cm band ( 1.24-1.3 GHz). Owners and operators of this
amplifier must be licensed amateur radio operators

https://kh6htv.files.wordpress.com/2023 ... tr-149.pdf
s58ru
 
Prispevkov: 1051
Pridružen: 28 Okt 2004, 21:07

Re: revija ATV

OdgovorNapisal/-a s58ru » 19 Dec 2023, 08:21

TV Rptrs Rptr-150.doc ( 12/18/23, kh6htv) p. 1 of 10
Boulder Amateur
Television Club
TV Repeater's
REPEATER
December, 2023
3ed edition, issue #150
BATVC web site: www.kh6htv.com
ATN web site: www.atn-tv.com
Jim Andrews, KH6HTV, editor - kh6htv@arrl.net www.kh6htv.com
News Flash ! - 8 December
WRC-23 Reaches Acceptable Conclusion on 23 cm Issue
IARU President Tim Ellam, VE6SH, said “This is a
very good result for the amateur services. The
decision reached at WRC-23 on this agenda item
makes NO CHANGE to the table of allocations
nor incorporates by reference M.2164 into the
Radio Regulations. The addition of a footnote that
provides guidance to administrations in the event of
interference to the RNSS is a good regulatory
outcome for amateurs and the primary users of this
band.” IARC-WARC team - 2023
To read more about this issue: https://www.iaru.org/recommendation-on- ... at-wrc-23/
also -- https://www.arrl.org/news/wrc-23-reache ... eter-issue
Special Issue on
ATV Antennas
TV Rptrs Rptr-150.doc ( 12/18/23, kh6htv) p. 2 of 10
The bulk of this issue of our ATV newsletter is devoted to antennas for ATV. The key word for such
antennas is -- "BROAD-BAND". Our TV signals are broad, 6 MHz typically, plus when we
transmit on several TV channels, we need to be able to cover the entire band. Our two most popular
bands for ATV are #1 - 70cm & #2 - 23cm. The required antenna band-widths are thus at least 30
MHz (420-450) and 60 MHz (1240-1300).
Any article on antennas will always be insufficent. There are so many choices out there, it is darn
near impossible to try to test all of them. Here in Boulder, we have some favorites used by most. For
a 70 cm Base Station, most prefer the 7.2 dBi, Diamond X-50NA. For a 70cm Yagi, the favorite is the
11 dBi, 6 element, M-Squared 440-6SS. For a 23 cm Yagi, the favorite is the 15 dBi, 14 element,
Directive Engineering DSE2414LYRMK. For our W0BTV repeater's receive antenna, we use the triband
(2m/70cm/23cm) Diamond X-6000A For our current Boulder ATV antenna testing, we are
using what antennas we can borrow from other hams. Definitely a very small sample of what is
available. All the more reason why we want to hear from other ATV ham groups.
Each ATV repeater group has their own favorite antennas. Please write to us with your list and tell us
why. We will then pass the info on to our readers. In this issue, Mario, N2JWP, an ATV pioneer on
Long Island, New York shares with us his favorite. What are yours ?
Antenna Tests: In years past we have run a couple of major testing sessions to evaluate antennas for
ATV service. The first was in 2011 and was documented in KH6HTV app. note AN-4, "Antennas for
Ham TV". The second was in 2017 and documented in KH6HTV app. note AN-40, "70cm Antennas
for ATV". Once again, here in 2023-24, we are now doing some more antenna testing. We will
report our results in a future newsletter. In none of the tests are the results totally accurate. They are
never performed on high quality antenna ranges nor using the methods employed by organizations such
as Georgia Tech Univ., FCC or NIST. So, gain figures from our tests are really not absolute, but in
reality comparisons between various antennas of their performance on our particular test range.
Polarization: Boulder uses Vertical for both 70 cm & 23 cm bands. Why? It was a historical
decision dating back to the early 90s. To support in the field ARES operations, both back-pack
portable and mobile, vertical antennas were deemed the most suitable. Other ATV groups have
elected to go horizontal. They typically are the out growth of weak signal SSB/CW DXers choice of
horizontal. What does your group use ? One advantage of using horizontal is the extra 20 dB of
isolation between the dominant vertical polarization used by the FM voice crowd and their multiple
repeaters.
Mario, N2JWP's Favorite ATV Antenna:
Marios says his favorite is one he has used successfully for many years.
It is a 22 element, K1FO Yagi antenna. He presently owns five of them.
He writes "It appears that the gentleman who designed it originally may
have passed and the design rights were possibly purchased." A search on
qrz.com shows the K1FO call sign is now held by the North-East Weak
Signal Group club.
TV Rptrs Rptr-150.doc ( 12/18/23, kh6htv) p. 3 of 10
A further web search for K1FO antennas reveals that they are now being built and sold by Directive
Systems & Engineering in Haymarket, Virginia. (www.directivesystems.com). They list the 22
element, K1FO Yagi as their model # DSEFO432-22. Their specs. are: freq. range = 432-435MHz,
15.8dBd Gain (i.e. +18dBi), 24o beam-width, 22dB F/B, vswr = 1.14:1 at resonance, It is a BIG
antenna with a 14 ft. long boom, center mount. DSE's price is $260 (kit).
How well does it perform away from the CW/SSB
frequency of 432 MHz ? That is an unknown.
Hopefully, some of you ATVers out there will
enlighten us. But Mario has put it to use on ATV
frequencies some distance away from 432 MHz.
Here is what he has to say about it. --- "An aged
gentlemen in my ATV group in the early nineties
had recommended it to me. Our receive frequency
was 421.25 MHz, transmit frequency was 434 MHz
for the ATV repeater. My 7-Pole Inter-digital Band-
Pass filters were cut for those frequencies I have
always been very satisfied with it since way back in
time. It performed stellar with the right weather
conditions in tropical ducting with my 4 beam
array. My best QSOs were with W3PHL in PA,
some 125 miles away. Our ATV transmissions to
the World Trade Center ATV repeater (pre 9/11 ! )
were reliable from 45 miles away with the analog
format. We would upon occasion experience sea
coast radar interference only, but that was it." Are
you happy with it? --- "Yes, for the length of time
that I had it, no damage apparent when taken
down." What can you tell us about it ? --- "The
only shortcoming it had when taken down were the
insulated standoffs were cracked, but the stiffness
of the copper used in the Gamma match held its
proper spacing intact on the boom."
Mario's K1FO, 22 element Yagi
Mario used his Comet VSWR meter recently to look at his ATV
antenna. He wasn't able to get directly to the antenna, but some
distance back in the ham shack. This is what he measured. It
definitely shows the antenna works best at the top end of the 70cm
band.
"DVB-T is a new game for me, hence I never dismantled my rack
mount Analog TV Transmitter and PC Electronics Receiver, which
has a 35 Watt pre-driver amp and a 100 Watt final and GaAs FET
preamp in the garage before leaving the house for the tower and
can be substituted by throwing a coaxial switch."
73 de Mario Klas, N2JWP, Deer Park, New York
TV Rptrs Rptr-150.doc ( 12/18/23, kh6htv) p. 4 of 10
Editor's Note: Mario is anxious to rejuvenate ATV activity in the New York City area. It has been
dorminant for a long time now after their ATV repeater on the World Trade Center went down on 9/11.
Other NYC area hams are encouraged to contact Mario. His email address is listed on www.qrz.com
Inexpensive Antenna Mount
for Camera Tripod
Jim, KH6HTV
Ten years ago, I published my app. note, AN-15, "Simple
Camera Tripod Antenna Bracket". I think it is worth
while to again bring it to the attention of you ATVers. It
is extremely simple to build and very low cost.
The antenna bracket is fabricated from a piece of 1 3/8", 14
gauge, perforated, steel flat bar. The steel bar is pre-drilled
with 3/8" holes. These bars are readily available from your
hardware or home improvement store. The thickness of the
bar is ideal to fit between the camera tripod mounting plate
and the camcorder. Only one or two holes need to be
drilled. An extra, small, #12 (0.189") hole is drilled next to
an existing large hole to accommodate the base plate
alignment pin. The camera mounting screw is typically
either a 1/4"-20 (small consumer cameras) or 3/8"-16 (large
professional cameras). Either screw will go through one of
the pre-drilled 3/8" holes. To mount the antenna, I use
either a BNC or SMA jack/jack (f/f) bulkhead adapter. For a BNC another existing hole on the top of
the bracket is enlarged to 1/2" for mounting the BNC bulkhead adapter. The bracket is then bent in two
locations as seen in the photo. The exact length of the bar and location of these bends depends upon
the size of the camera used and the desired antenna height above the camera. A 50 Ω, coax cable is
used to attach the antenna to the TV transmitter.
TV Rptrs Rptr-150.doc ( 12/18/23, kh6htv) p. 5 of 10
REFERENCE GAIN -- 1/4 λ Ground Plane Antenna
Jim, KH6HTV
We could just simply do comparison tests between various
antennas and rate them accordingly. However, it would really be
nice if we could assign an absolute gain value in dBi. To do this,
we need to have some reference antenna to compare our other
antennas to. For microwaves, we typically use a standard gain,
flared waveguide horn antenna. For HF & VHF measurements,
the classical 1/2 wave ( λ ) dipole antenna is typically used. For
vertical polarization on VHF/UHF, we typically use a 1/4 λ ground
plane antenna. It consists of a single 1/4 λ vertical radiator rod
plus four, 1/4 λ radials drooping down at a 45o angle.
Using the EZNEC antenna modeling program, it is straight
forward to determine this antenna's predicted performance.
I designed on EZNEC such an antenna for the 70 cm band. It was designed for a center frequency of
434 MHz and used #14 gauge, solid copper wires for the elements. The lengths of both the vertical
radiator and the four radials were optimized on EZNEC. The final design was with a vertical radiator
of 6.2". The four radials were 6.7".
EZNEC calculations: Free Space Gain = 2.1 dBi flat across 70 cm band. Omni directional
performance in the azimuth (X-Y) plane. min. VSWR = 1.03:1 at 434 MHz, 1.5:1 vswr limits (-14
dB return loss) = 418 & 452 MHz
An actual antenna was then built using a bulkhead mount, square flange, type N (f) connector. This
antenna is shown on the previous page mounted on the camera/antenna bracket. For eye safety, I
looped the ends of all the 14 ga. copper wires back on themselves and soldered the loop to the wire.
The lengths were then measured and cut to the tips of these loops. I then measured the vswr with a
Nano-VNA. The results were: min. vswr = 1.05:1 at 430 MHz, < 1.5:1 (417-463), < 2:1 (409-470)
TV Rptrs Rptr-150.doc ( 12/18/23, kh6htv) p. 6 of 10
& < 3:1 (396-481 MHz) This antenna is thus a very good match to 50 Ω over the entire 70 cm
amateur band.
So, can we use the calculated Gain of +2.1 dBi as our reference antenna ? Well yes and no. It is a
starting place. It is the theoretical gain for the antenna out in free space with nothing else to
perturbate the EM fields. With EZNEC, we can then start to add disturbances and see their effects on
both the far field patterns and the gain on the horizon. First off, we have the coax cable feed line, plus
the support mast dropping down vertically. A metal rod of various lengths can be tried with EZNEC
to simulate these. It causes some dimpling in the pattern. It remains omni-directional, but now adds
some uncertainty of ±1 dB or so to the +2.1 dBi gain figure. A major disturbance is to then simulate
in EZNEC the effects of using the antenna over real earth. We now have ground reflections to deal
with. They can get to be much more serious in distorting the far field pattern and cause greater
variations in the gain.
But, being real "amateurs", not true antenna scientists, I guess for lack of better tools, we might as well
go ahead and use the +2.1 dBi figure for our inter-comparisons of our various ATV antennas.
73 de Jim, KH6HTV
=========================================================================
DIY - your own 70cm Yagi Antenna
Jim, KH6HTV
While the M-Squared 440-6SS Yagi is my personal favorite, broadband,
Yagi for 70 cm, it has recently gotten quite expensive at
$169. It previously sold for many years at $100. The
construction of it appears to be quite simple and could be
duplicated in your own garage work shop. The yagi consists of a
total of six elements. They are a driven element, one reflector
element, and four director elements. The elements are 3/16" dia.,
solid aluminum rods appropriately spaced on a 3 ft, 1" dia. boom.
I have measured them on my own antenna. 440-6SS Yagi
Here are the lengths and their respective positions relative to the driven element.
#1 Reflector: 34.7cm (-8.3cm) #2 Driven Element: 33.1cm (0 cm ref)
#3 Director: 30.7cm (7.4cm), #4 Director: 29.6cm (23.7cm)
#5 Director: 28.8cm (46.3cm) #6 Director: 28.2cm (66.7cm)
M2 does not electrically attach the rod elements to the support
boom. They pass through the boom and are held in place with
insulating plastic spacers.
Here is a close-up photo of the construction of their Z - matching
Gamma match and the UHF coax connector showing how they are
attached to the boom and the driven element.
TV Rptrs Rptr-150.doc ( 12/18/23, kh6htv) p. 7 of 10
EZNEC Modeling: The M2 yagi is an easy one to model. Simply enter the above data into the
wire table for a total of 6 wires. Place the excitation source in the middle of wire #2.
The following is the predicted performance in Free Space. The VSWR plot shows the min. of 1.41:1
(-15.3dB RL) at 425 MHz with an impedance of about 35-36 Ω. Thus showing the need for the
Gamma Match. If we then assume a gamma match is used and then replot the vswr using a ref. Z of
35 Ω we get this plot with a min. vswr of 1.006 at 423 MHz. The < 1.5:1 BW is 413-439 MHz. The
< 2:1 BW is 410-448 MHz. The free space far field calculations show the below plots. The max.
theoretical, free space gain is +11.5dBi, essentially the same as the M2 specs.
Azimuth Field Pattern Elevation Field Pattern
On my real M2 Yagi, I measured a vswr min. of 1.2:1 at 436 MHz, < 1.5:1 (416-446) & < 2:1 (410-453
MHz) & < 3:1 (408-457). My measured < 2:1 band-width very closely matches the EZNEC
calculations. These indicate that it should be a good antenna over the whole 420-450 MHz, 70 cm
amateur band.
TV Rptrs Rptr-150.doc ( 12/18/23, kh6htv) p. 8 of 10
BOULDER ATV ANTENNA TESTING
We have started this winter a project to test various 70 cm antennas for possible use for ATV. We are
looking to test four categories of antennas. They are: (1) Base Station, Omni-Directional (2)
Directional Yagis, (3) Mobile Antennas & (4) Hand-Held HT Antennas. All with vertical
polarization. We plan to test all antennas on all five, 6 MHz, ATV channels in the 70 cm band.
View from Lowell Blvd. test site to W0BTV-ATV repeater, 13 miles west
A "dry-run" was done on Dec. 6th on a single frequency (423 MHz) using the W0BTV repeater's
Beacon mode as the test source. A few antennas were tested that day. For a receiver we used a preamp
followed by a 3dB power splitter. One arm of the splitter went to a Hi-Des HV-110 receiver.
The other went to a TinySA-Ultra spectrum analyzer. Actual signal strengths in dBm were recorded.
We also recorded s/n.
Legionaire's Hill - Receive Test Site Don, N0YE, & Larry, N8GGG
Then on Saturday, Dec. 16th, we tried to do a major test session with lots of participants and antennas
to be tested. We set up our receivers on Legionaire's Hill county park, east of the City of Boulder. It
is on high ground overlooking Boulder Valley and the Rocky mountains to the west. It is remote from
any other structures. The terrain immediately to the west of the parking lot slopes down hill rapidly
TV Rptrs Rptr-150.doc ( 12/18/23, kh6htv) p. 9 of 10
which should reduce the effects of ground reflections and clutter from our measurements. Steve,
WA0TQG, from his home on Sugar Loaf mountain, 11 miles to the west, provided our DVB-T test
signal on all five ATV channels. Things did not go well this time. We had technical glitches and then
after only about an hour the wind started blowing really hard. So we abruptly terminated the test
session. To be continued sometime in the future.
Rick, KK0COP, taking data George, N0RUX & Doshia, KB0NAS
While the Dec. 16th test was a "Bust", we did get some useful data to be shared on Dec. 6th. The
results that day were strictly on a single frequency, 423 MHz at the bottom of the 70 cm band. The
two Yagis tested that day came in close to the anticipated +11 dBi gain. They were a very old, 6
element KLM (unknown model #) and an M-Squared 440-6SS. The KLM tested out at +9 dBi. The
M-Squared tested out at +10 dBi.
Diamond X-50 Diamond X-6000
We also tested two Diamond base station omni, vertical antennas. They were the X-50NA and the X-
6000A. Tests in previous years had shown the X-50 to be broad-band and worked well across the
entire 70 cm band,. The X-6000 only worked, but worked quite well at the top end of the band, but had
TV Rptrs Rptr-150.doc ( 12/18/23, kh6htv) p. 10 of 10
negative gain at the bottom end of the band. The Dec. 6th tests confirmed this at 423 MHz. We
measured +6 dBi (spec. 7.2 dBi) for the X-50. The X-6000 showed -11 dBi. See the above measured
spectrums.
73 de Jim, KH6HTV, Boulder, Colorado
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:
https://kh6htv.com/application-notes/
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: https://batc.org.uk/live/ 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: https://kh6htv.com/newsletter/
ATV HAM ADS -- 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.
==================================================

https://kh6htv.files.wordpress.com/2023 ... tr-150.pdf
s58ru
 
Prispevkov: 1051
Pridružen: 28 Okt 2004, 21:07

Re: revija ATV

OdgovorNapisal/-a s58ru » 01 Jan 2024, 08:20

TV Rptrs Rptr-151.doc ( 12/31/23, kh6htv) p. 1 of 14
Boulder Amateur
Television Club
TV Repeater's
REPEATER
January, 2024
issue #151
BATVC web site: www.kh6htv.com
ATN web site: www.atn-tv.com
Jim Andrews, KH6HTV, editor - kh6htv@arrl.net www.kh6htv.com
BREAKING NEWS BULLETIN: 21 Dec. 2023
European Space Agency -- EXPLORES POSSIBLE
MICROWAVE AMATEUR PAYLOAD ON SATELLITE
for North America, including DTV !
TV Rptrs Rptr-151.doc ( 12/31/23, kh6htv) p. 2 of 14
from: Amateur Radio Newsline Report 2407 for Friday December 15th, 2023
Is there room aboard a satellite for a geostationary microwave amateur payload to cover part of North
America? --- Jeremy Boot G4NJH looks at that question.
JEREMY: The European Space Agency has an approved proposal to investigate sharing a commercial
geostationary satellite contract to piggy-back a microwave amateur payload on it to cover Europe and
part of North America.
The investigatory project was presented by ESA's Frank Zeppenfeldt, PDØAP, to the AMSAT-UK
Colloquium in Milton Keynes on the 14th of October. Frank described a payload that would have both
an amateur radio and educational role, with two uplink transponders on 5.6 GHz and two downlink
transponders on 10 GHz.
The payload would be capable of handling narrow-band modes such as CW and SSB and narrow-band
digital modes but would also have the capacity for wide-band modes such as
amateur TV. To see Frank's presentation, follow the link to a YouTube video that appears in the
text version of this week's newscast at arnewsline.org
( https://www.youtube.com/watch?v=_FTvlEyDa1Y )
The proposal from AMSAT-UK and the British Amateur Television Club has input and support from
the newly incorporated AMSAT-CA's Technical Working Group as well as from AMSAT-USA.
According to a November 30th position paper from AMSAT-CA's president Stefan Wagener, VE4SW,
and technical director Levente Buzas, VA7QF, a number of amateur radio satellite associations are
helping Frank promote the project to commercial satellite operators in 2024 during the World Satellite
Business Week.
Stefan told Newsline that Frank hopes to use the QO-100 geostationary amateur payload on Qatar's
Es’hail 2 satellite as an example so another commercial partners can be identified to carry a similar
payload in a position over the Atlantic to cover Europe and Canada. The study is being undertaken
with the help of €250,000 in ESA funds.
=========================================================================
Special Issue on Japan's ISDB-T
What is the Difference
between DVB-T and ISDB-T ?
Mijo Kovacevic, S51KQ, Vojnik, Slovenia
TV Rptrs Rptr-151.doc ( 12/31/23, kh6htv) p. 3 of 14
Four transmission standards are currently in use for
terrestrial digital TV.
most of the world: DVB-T and DVB-T2
USA , Canada, Mexico & S. Korea: ATSC
China, Asia: DTMB
South America, Botswana, Japan, Philippines: ISDB-T
The DVB-T system enables transmissions in bandwidths of
6, 7 and 8 MHz, which also means three different symbol
rates. ISDB-T only knows 6 and 8 MHz bandwidths.
Both transmission methods use COFDM modulation (orthogonal freq. division multiplexing), so they
offer users similar connection and image qualities
ISDB-T is a much less widespread alternative to the real DVB-T. ISDB was developed in Japan for the
needs of Japanese people, for the transmission of digital radio and television. They also know ISDB-S
(satellites) and ISDB-C (cable TV). The ISDB standard provides compression for multiplex in MPEG-
2 and MPEG-4 standard, as well as video/audio coding (MPEG2 or H.264). The latter enables the
HDTV image standard. The difference in picture quality and bandwidth compared to DVB-S2 is huge.
With DVB-S2 and H.265 compression, you can easily achieve a high-quality image at a very low
bandwidth (SR 333 KS), which is impossible to achieve in H.264 compression. The difference is
roughly as follows: with H.265, the image is almost 1x better than the lower standard with the same
bandwidth and higher resolution. However, H.265 requires much more capable processing both on
transmission and reception, and in real time! For comparison, I add below a couple of images captured
from live video on the QO-100.
TV Rptrs Rptr-151.doc ( 12/31/23, kh6htv) p. 4 of 14
It's also no surprise that the Japanese are
making ATV in their native ISDB standard.
They are mostly active at 5.7 GHz and
above. On frequencies below 1.2 GHz it is
probably impossible for them to work due to
the bandwidth required for ISDB. Here are
a couple of interesting links:
https://www.youtube.com/@sekizakifumio3709/
videos
https://www.facebook.com/groups/
2375023609443269/
The above image was captured from H.264 and 333 KS, with 60% less image data - lower resolution,
because as big as it is above, in H.264 and with this small bandwidth (333 KS) it would not be fluid, or
it would not pass through at all ...
Images captured from live video, H.265 encoding and 333 KS
=========================================================================
Successful Single Frequency
ISDB-T Transmission Relay
Fumio Sekizaki, JA0RUZ
On December 3rd, Japan's digital ATV (ISDB-T system) successfully relayed full high-definition
transmission using the same frequency using 5745MHz. We tested with the following configuration:
① Kimitsu City, Chiba Prefecture: JH1AOY/1 5745MHz transmission, Span = 96km
② Dodairayama, Saitama Prefecture: 7K2HKS/1 5745MHz reception, 50m apart, HD-SDI connection
   *Scenery footage from the relay location is mixed with the relay video and sent.
TV Rptrs Rptr-151.doc ( 12/31/23, kh6htv) p. 5 of 14
③ Dodairayama, Saitama Prefecture: JA0RUZ/1 5745MHz transmission, Span = 62km
④ Gunma prefecture observation deck: JA0SIO/1 reception
① to are surrounded by mountains and ④ cannot be seen, so 5.7GHz FHD-ATV waves cannot directly
reach them.
Please see the received videos sent from ① to ④ https://www.youtube.com/watch?v=-_hm2U6tEX4
The videos sent from ④ to ③ are  https://www.youtube.com/watch?v=uCduUpMGWcI
Normally, when transmitting the same frequency wave at a close distance, it loops around to the
receiving station and the target wave becomes unreceivable, but in the case of ISDB-T, if certain
conditions are met, relaying on the same frequency (Single Frequency Network) becomes possible.
I've never heard of this type of "relay using the same frequency" on a full high-definition ATV, so I
guess this is the first time it's happened in amateur radio.
Please note that it is also written on my blog for your reference.
https://blog.goo.ne.jp/ja0ruz/e/64b50fe ... 7ff97d3077
https://blog.goo.ne.jp/ja0ruz/e/f74c749 ... =entry_awp
TV Rptrs Rptr-151.doc ( 12/31/23, kh6htv) p. 6 of 14
TV Rptrs Rptr-151.doc ( 12/31/23, kh6htv) p. 7 of 14
=========================================================================
DVB-T Peak Power
vs. Average
Jim, KH6HTV
I recently had an inquiry from a customer
who was concerned about the PEP (peak
envelope power) out of one of my rf linear
power amplifiers. He had an application
using the amplifier in a high altitude rocket
and was concerned about exceeding limits at
which arcing might occur when the air
pressure drops to almost vacuum.
So to answer his question -- back to the text books and the test bench to verify some numbers.
First from the DVB-T Bible [1] -- What does it say ? "The theoretical Crest Factor (i.e. the ratio
between the maximum peak amplitude and the RMS value of the DVB-T signals) is 41 dB in 8K mode
(35 dB in 2K mode). ....... It must be noted that these are theoretical values which, due to the limited
resolution of signal processing and clipping, cannot occur in practice. Practical values are of the order
of magnitude about 15 dB ( for modulators ) and about 13 dB for commercial, broadcast, DVB-T high
power transmitters." (page 401)
Reference [1] "Digital Video and Audio Broadcasting Technology - A Practical Engineering Guide",
by W. Fischer (Rhode & Schwartz TV engineer), 3ed edition, Springer, 2010.
TV Rptrs Rptr-151.doc ( 12/31/23, kh6htv) p. 8 of 14
Test Bench: The above screen grab from my Rigol DSA-815 spectrum analyzer shows the
measurement of a DVB-T, 6 MHz BW, QPSK, 8K signal. The signal source was a Hi-Des model HV-
320E modulator. The internal attenuator was set to -7dB, to set the rf output rms power level to about
0dBm. The actual value measured on an HP-432A, thermistor power meter was +0.5dBm.
The bottom, yellow trace, is the normal measurement of such a signal using the ITU recommended
analyzer settings [ref. 1, pp. 425-428] of: span = 20 MHz, resolution band-width = 30 kHz, video
band-width = 300 kHz, detector = RMS, sweep = 2 seconds. I also use 10 averages.
The middle, magenta trace, is with the same settings with the RMS detector, except both the resolution
and video band-widths were set to the max. of 1 MHz.
The top, cyan trace is again with 1 MHz BW settings, but the detector has now been changed from
RMS to Positive Peak. This will help us measure the Crest Factor.
Now the marker function was used to measure the displayed signal level in dBm at the center
frequency on each trace. Yellow = -22.18 dBm, Magenta = -7.46 dBm, and Cyan = +2.62 dBm.
So what do these numbers tell us ?
(1) Well first, with the normal measurement (yellow trace), it tells us there is an offset of 22.6 dB
between the power measured at the center frequency (30kHz BW) and the total RMS channel power as
measured by the HP thermistor power meter. (Note: Analyzers such as the TinySA-Ultra can be
configured to measure the Total Channel Power by integrating the power measurement across the
whole width of the TV channel. The Rigol can also measure total channel power, but only if an
expensive optional upgrade is paid for and enabled. ) This total channel power value would then match
that obtained using the HP power meter.
(2) When we use the max. 1 MHz BW, we are assured of capturing any possible peaks in the DVBT
signal. Thus the difference between using the RMS detector and the Peak detector tells us the crest
factor. For our HV-320 modulator it is = +2.62 dBm - (7.46 dBm) = 10.08 dB ≈ 10 dB
This is in the ball park of what W. Fisher told us in the "DVB-T Bible".
I also repeated this same test, but looked at the RF output of one of my model 70-9B, amplifiers. It
was putting out about 10 Watts (+40dBm) RMS of DVB-T power with shoulder break-points of about -
31dB. These amplifiers are capable of max. saturated power of the order of 70 Watts. The presence
of the out of channel power evidenced by the spectrum shoulders is also an indication that some
clipping, and hence distortion, is occurring within the amplifier. This means we typically are leaving
about 8-9 dB of head-room to accommodate the peaks in the random, noise-like, digital signal.
Looking at the spectrum displays at 1 MHz BW (magenta & cyan traces) for the amplifier for the RMS
vs. Peak detectors, I saw a Crest Factor of about 9 dB. Very consistant with the 10W / 70 W
headroom setup.
73 de Jim, KH6HTV, Boulder, Colorado
=========================================================================
TV Rptrs Rptr-151.doc ( 12/31/23, kh6htv) p. 9 of 14
KH6HTV Video
Announces a
Break-Through
in 23 cm, DTV Amplifier
Efficiency New 23-12 Amplifier rear view of 23-12
In the past, the use of Digital ATV on the 23 cm band for out in the field, portable, battery powered,
emergency operations for ARES has been hampered by the very poor DC to RF conversion efficiency
of available linear, rf power amplifiers. Most DATV hams have been using the Mitsubishi brick
amplifier modules as the heart of their amplifiers. These bricks work well as linear amplifiers for
digital TV service, but at the expense of being DC power hogs. For 23 cm, Mitsubishi only offers one
brick, their model RA18H1213G.
Since 2016, KH6HTV Video has been selling a single model of amplifier for 23 cm DTV service, it's
the model 23-11A, which uses the Mitsubishi brick. With it, we are able to achieve 4.5 Watts
(+36.5dBm) of DTV rf power at 23 cms. But at the expense of 90 Watts of DC power ( 6.5 Amps @
+13.8Vdc). A measly 5% dc to rf power conversion efficiency. Who wants to lug a big heavy
battery out in the field for ARES for an amplifier that sucks 6.5 Amps and only gives out 4.5 Watts of
RF ? ? ! !
Now, with the introduction of the NEW model 23-12 amplifier, we are able to achieve a much better dc
to rf conversion efficiency of 27% for DTV service. ( 45% for FM/CW ). The new 23-12 amplifier
has a very linear Pout vs. Pin curve. 13 Watts (P saturated), 9 Watts (-1dB gain compression), 8 Watts
( - 0.5dB gain compression ) Thus for FM/CW service, one obtains 13 Watts. For SSB or Analog TV
service 8 Watts PEP. And for Digital TV service 2 Watts (+33dBm) average power. Running 2 to 2.2
Watts DTV, it only pulls 0.9 Amps at +13.8Vdc.
For more details, see the web site: www.kh6htv.com
=========================================================================
TV Rptrs Rptr-151.doc ( 12/31/23, kh6htv) p. 10 of 14
Pete, WB2DVS & Debbie, WB2DVT as seen by Bob test pattern signals from KH6HTV relayed by W0BTV
BATVC NEWS: ATV viewer, Bob, WB0NRV, in Firestone, Colorado, on the Dec. 21st,
ATV net reported success finally in receiving P5/Q5 pictures from the W0BTV, DVB-T repeater in
Boulder. The distance was 21 miles (34km). He has sent us the above photos as his ATV QSL
confirmation. Bob used this time a Comet GP-3, 2m/70cm, omni-directional antenna at 16 ft. with
about 40 ft. of Belden 9913 coax cable. He first received the picture on the left using a very low cost
Pantesat receiver. He then switched to a Hi-Des HV-110 to make actual signal strength measurements.
The HV-110 showed an excellent received signal of -80 dBm with a s/n of 16 dB.
Dec. 28th -- A week later, after our regular Thursday afternoon ATV net, Bob then tried transmitting to
W0BTV repeater again using the GP-3 antenna. He was able to successfully key up the repeater as
shown by the above two off the air photos. Looking at the repeater's S meter reading of -61dBm and
throwing in the know offset of 24dB, Bob was hitting the repeater with a -85dBm signal. His picture
was not perfect, with a lot of freeze frames. If our repeater site were free from 70cm RFI, he would
have gotten perfect pictures through the repeater.
=========================================================================
TV Rptrs Rptr-151.doc ( 12/31/23, kh6htv) p. 11 of 14
BATC - U.K. The latest issue #282 of the BATC's quarterly magazine, CQ-TV is
just out. Again, it has several articles of interest. Their big news to share is their major problem of
losing their supplier of the Serit FTS-4334 NIM / RF Tuner has been solved. This tuner was a Key
component in several of the BATC's digital TV receiver projects. Chris, PA3CRX, has an article of
interest to analog TV types. "Evaluation of the Quality of Transmitted and Received Analogue Video
Signals". Several other articles, mostly of interest locally in the U.K. The magazine is 36 pages.
=========================================================================
Feed-Back:
ATV Antennas: Bill, K0RZ, writes -- "Looks like the MSquared
and the KLM Yagis perform as expected. In case you
aren’t aware of the connection, Mike, K6MYC, (the M in KLM)
played in these two Yagi antennas, he designed the KLM 6 element
and now is the owner of M-Squared and the 440-6SS is his latest
design."
Interesting reading Mike's QRZ.com bio with includes ... " I soon
started KLM electronics with (K)en Holladay K6HCP, (L)eland
Mike, K6MYC
Ferrar K6KBE and (M)ike Staal in 1971. I designed the KT34A and 'XA along with hundreds of other
antennas and soon we were building C band satellite dishes and receivers. KLM was sold in 1982 and
a couple years later my wife Myrna (K6MYM) and I started M2 Enterprises later to become M2
Antenna Systems Inc. See our web site at www.m2inc.com"
Editor's Note: We got a lot of Feed-Back from the previous issue #150 on ATV antennas. We will be
publishing it in our next issue #152.
=========================================================================
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:
https://kh6htv.com/application-notes/
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: https://batc.org.uk/live/ 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-151.doc ( 12/31/23, kh6htv) p. 12 of 14
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: https://kh6htv.com/newsletter/
ATV HAM ADS -- 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 - 70cm Amplifier: I am looking for an Amplifier for my mobile ATV unit.
At this point, I am still using analog video with a VM – 70 from Videolynx.
Do you know if any amplifiers are available in the sub $300 price range? Used of course. And where
I might be able to buy one. It is pretty tricky to find one. I was thinking somewhere in the
neighborhood of 100 Watts. Jack McNulty, KE8PYF, McNultyj@gojo.com
========================================================================
Commercial 70cm, DVB-T Amplifier
… NEW old stock ... For Sale
420-470 MHz, Max. Output DVB power: 60 Watt, Max. Output power CW mode: more than 150W,
43-51dB Gain (adjustable), requires +28Vdc & +8Vdc, sold without heat sink, but with PCB cover.
Price is 470 Euros, including shipping. More details at:
https://oe7dbh.blogspot.com/2023/11/70c ... ifier.html
interested ? - contact Darko Banko 9a6rzn@gmail.com
------------------------------
TV Rptrs Rptr-151.doc ( 12/31/23, kh6htv) p. 13 of 14
TV

https://kh6htv.files.wordpress.com/2023 ... tr-151.pdf
s58ru
 
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Re: revija ATV

OdgovorNapisal/-a s58ru » 10 Jan 2024, 14:50

TV Rptrs Rptr-152.doc ( 1/10/24, kh6htv) p. 1 of 13
Boulder Amateur
Television Club
TV Repeater's
REPEATER
January, 2024
2ed edition, issue #152
BATVC web site: www.kh6htv.com
ATN web site: www.atn-tv.com
Jim Andrews, KH6HTV, editor - kh6htv@arrl.net www.kh6htv.com
ATV ANTENNAS
--- continued ---
In our previous, Dec. 2023, issue #150, we started discussing
antennas for ATV. We encouraged feed-back from our readers.
Yeah ! We have gotten it and are reprinting it here. We still
encourage others to also write to us and tell us about your favorite
ATV antennas.
Cheap ! Yagis
Doug Reed, N0NAS writes --- "Regarding your ATV
antenna tests, have you ever looked at the WA5VJB
"Cheap Yagi" wooden beam antennas? Kent Britain is
an antenna designer among other things and wrote a
column in CQ magazine for quite a few years.
TV Rptrs Rptr-152.doc ( 1/10/24, kh6htv) p. 2 of 13
His "Cheap Yagis" are near zero cost and have been duplicated many thousands of times. They will
work if built according to directions, and will fail if "improved" by the builder. His original designs
were for SSB, but since then he has published FM, ATV, HDTV, and antennas for other bands.
Use copper wire for the driven element and just
about anything for the other elements. Try to stay
with the diameter or wire gauge specified. To tune
it, you mostly adjust the driven element loop and
spacing from the reflector and director elements.
Stay with wood of the thickness he specified. Build
it to spec and it will have the specified gain. We use
a series of these antennas as gain reference
standards on the NLRS antenna range and during
CSVHFS conferences. Here are some good
references to Kent's Yagis."
http://wa5vjb.com/yagi-pdf/cheapyagi.pdf
http://wa5vjb.com/references.html
https://www.repeater-builder.com/antenn ... -yagis.pdf
Doug writes further --- "I'm slightly surprised if none of your group have heard of "Cheap Yagis"
before! Kent is pretty famous in the VHF-Microwave weak signal world for these antennas and his
PCB antennas for the microwave bands. He also usually runs the antenna measurement range at
whatever weak signal conference he attends. Beyond 420 MHz, I expect most antennas are broadband
enough not to need a special model. It really worked nice to use a NanoVNA to adjust the SWR of a
newly built antenna."
73 de Doug Reed, N0NAS, St. Paul, Minnesota
Editor's Note: Check out Kent's web site at ( www.wa5vjb.com ). I have in the past purchased Kent's
microwave PCB antennas and they do work.
========================================================================
Pneumatic ATV
Antenna Mast Project
The antenna mast project that I have been working on is nearing
completion. The pneumatic mast , extends to 25 ft, and folds over for
stowage in the horizontal position. I modified a "traffic bollard" for the
fold-over base. It takes about two minutes to inflate the extendable mast
using a portable tire inflator. A remote flux-gate compass has been added
to this configuration. The remote compass employs a magnetometer is
used for accurate antenna orientation. See the photos below.
73 de Dave, AH2AR, Dayton, Ohio - DARA
photo shows Pneumatic Mast prior to Inflation
(70cm Antenna and 23cm Antenna used for ATV)
TV Rptrs Rptr-152.doc ( 1/10/24, kh6htv) p. 3 of 13
'Aussie' DATV
Repeater Antennas
Peter Cossins, VK3BFG, writes to tell us what the
Melbourne, Australia, ATV repeater group is using
for antennas.
"Hi Jim .. on the antenna theme .... VK3RTV has
four 23 cm horizontally polarized Dual Quads each
oriented towards main service areas. The 70 cm
transmit antenna is a vertically polarized omni.
The dual quads are easy to manufacture once you
develop a means of bending that results in an accurate
profile. VK3RTV's quads are fed with hardline inside
the panel enclosure. The enclosure is type used for
electrical switchboards. A check on any attenuation
occurring when sealed up resulted in no measurable
effect. The matching sections are brass tube available
from hobby shops with the inner being the stripped out sections from 75 ohm cable which just fits. This
means that all the hot soldering can take place and then the inner 75 ohm cable inserted. Using this
overall technique the line lengths can be very accurately determined for the operating frequency.
Looking at the frequency response plots show that the whole assembly is broadband however. The
vertical is also broadband so both types ideal for ATV. ---- Performance figures are attached.
I have in hand a slotted omni vertical for 2.4G . The plan is to install this with a masthead down
converter to 23 cms. A Combo DVB/S/S2/T can then be used as a receiver. Will undergo testing of
TV Rptrs Rptr-152.doc ( 1/10/24, kh6htv) p. 4 of 13
the system before installation. I have yet to undertake any performance figures for it but it is rated at
15dBi."
Regards Peter Cossins, VK3BFG
Front with radome attached Rear Panel
Dual Panel Matching Network
1246 1255 MHz Dual-Quads 1278
VK3RTV 70cm Transmitting Vertical Antenna
TV Rptrs Rptr-152.doc ( 1/10/24, kh6htv) p. 5 of 13
ANTENNA TRIPOD MOBILE ANCHOR
Jim, KH6HTV
How many of you fellow ATV hams like to go out in the field for ATV DXing ? We want to be able to
set up on a temporary basis a big, bulky antenna such as a high gain Yagi. But we don't want it to then
fall over and break, or worse yet fall on someone and injure them. We need some support
arrangement. Guy wires are one obvious solution. But they are a pain to set up and are also a tripping
hazard. Here is a very simple solution. Let your automobile be the anchor for your big Yagi. I
typically use a standard roof mount, antenna tripod and some sections of standard 1 1/4" antenna mast
for my portable, in the field ATV operations. I built very simply an automobile anchor for the
tripod/mast using two planks of 1x6" wood. I made a simple "T" with them and bolted them together
with (3) 1/4-24 bolts/nuts. I then also drilled 1/4" holes for more bolts to attach the three legs of the
antenna tripod. Now, after it is assembled, simply drive one wheel of your automobile over the
extended plank to firmly anchor your antenna assembly.
=========================================================================
Test Results for 23 cm Antennas
for ATV Service
Jim Andrews, KH6HTV & Don Nelson, N0YE
The Boulder, Colorado ATV group has undertaken a project this winter to characterize 70 cm and 23
cm antennas to determine which are most suitable to recommend to other hams for broad-band, ATV
service. We are preferably looking for commercial antennas which are "Broad-Band" and work well
across the entire band. Unfortunately, most manufacturers provide very skimpy specs. and some
actually give out no information at all about the actual performance of their antennas. Some simply
TV Rptrs Rptr-152.doc ( 1/10/24, kh6htv) p. 6 of 13
list the mechanical dimensions, etc. We have had several false starts on our testing, but finally have hit
upon a suitable antenna range and procedure. Here is a summary table with our test results on the
commercial 23 cm antennas which we have tested. We also tested some home-brew antennas but they
are omitted from this table. The results were only shared with the builders. We will publish the results
for 70 cm antennas in the next newsletter. The complete details of the antennas and tests will be
published soon in an application note posted on our web site. Obviously, not all commercially
available antennas were tested, only those which various members owned and contributed to the test.
We tested four categories: Yagis, Base Station Omnis, Mobile and HT. We were quite encouraged
by the results and how close some of them came to manufacturer's specifications. Others were quite
far off, with some even showing negative gains. The reference antenna we used was a 1/4 wave
ground plane with +2.2 dBi gain.
23 cm ANTENNA GAINS in dBi
ANTENNA Mfgr's
Gain
Spec
1243
MHz
1255
MHz
1267
MHz
1279
MHz
1291
MHz
YAGI ANTENNAS
Antennas-Amplifiers
70cm23WB11
(70/23cm, 4/7 elements, 20" boom, rear mt)
11.4dBi 10.7dBi 11.8dBi 12.1dBi 12.2dBi 11.0dBi
Directive Systems
DSE2414LYRMK
( 14 elements, 36" boom, rear mt )
15dBi 14.5dBi 16.2dBi 16.9dBi 16.6dBi 15.5dBi
BASE STATION - OMNI
Diamond X6000A
(2m/70cm/23cm, 126" tall)
10dBi 8.2dBi 7.1dBi 6.6dBi 6.0dBi 4.0dBi
MOBILE ANTENNAS
Diamond NR2000NA
(2m/70cm/23cm, 41" tall)
9.7dBi -1.9dBi -1.0dBi 2.9dBi 7.1dBi 6.1dBi
HAND-HELD ANTENNAS
Diamond SRH999
(6m/2m/70cm/23cm, 19.5" tall)
none 3.2dBi 4.2dBi 3.7dBi 3.2dBi 2.8dBi
KH6HTV Reference 1/4 λ GP 2.2dBi 2.2dBi 2.2dBi 2.2dBi 2.2dBi 2.2dBi
=========================================================================
TV Rptrs Rptr-152.doc ( 1/10/24, kh6htv) p. 7 of 13
DIAMOND X50NA
We plan to feature in each issue of this ATV
newsletter some of the antennas which we have
tested and we recommend for use for ATV.
The favorite base station, omni-directional, vertical
antenna with the Boulder ATV hams is the
Diamond X50NA. We have found that it gives
decent gain and a flat response across the entire 70
cm band.
The X50NA is dual-band for both the 2 meter and
70 cm bands. It has a reasonable, manageable
height of 5' 7". It also has a reasonable cost of
$100. The image shown on the right is the total
information given about it by Diamond.
Diamond says the X-50's gain is 4.5 dBi on 2 m and 7.2 dBi on 70 cm. They do not specify over what
frequency range. We did major antenna tests in 2011, 2017 and once again here in 2023-24. The
previous tests were documented in KH6HTV application notes, AN-4 & AN-40. For each of the test
sessions, the X-50 was one of the antennas tested. In earlier tests, we also tested two other Diamond
omni antennas, their X-200 and X-6000. The X-200 was also a dual-band (2m/70cm) and was taller
at 8' 4" and supposed to have 1 dB more gain. The X-6000 was a tri-band (2m/70cm/23cm) and
considerably taller at 10' 6" and supposed to have 2 dB more gain.
While we got different gain values (in dBi) for these antennas in different test sessions, they all
definitely showed similar frequency response trends across the entire 70cm band from 420 to 450 MHz.
The X-50 always showed a good, uniform gain across the entire 70cm band. Both the X-200 and X-
6000 showed gain similar to Diamond's specifications, but only at the very high end of the band in the
top FM portion of the band (445-450 MHz). They showed very poor gain on the lower portion of the
band.
The tests run in 2011 and 2017 were done using CW signal sources. Our most recent tests were
performed using actual, 6 MHz, DVB-T TV signals. Thus, the most recent results are the average
gain across a wide, 6 MHz TV channel. Here is our most recent test results for the Diamond X-50
antenna on the 70 cm band. Diamond's spec. was 7.2 dBi, which was hit at the top end of the band.
423 MHz 429 MHz 435 MHz 441 MHz 447 MHz
5.4 dBi 5.5 dBi 6.5 dBi 6.8 dBi 7.6 dBi
TV Rptrs Rptr-152.doc ( 1/10/24, kh6htv) p. 8 of 13
Return Loss of the Diamond X50NA Antenna: center freq = 435 MHz, span = 50 MHz
5 dB/div & 5 MHz/div. The 0 dB reference line is 1 division down from the top.
We also measured the Return Loss (RL) for every antenna tested. We use a Rigol DSA-815 spectrum
analyzer with it's built-in tracking generator and an external 20dB directional coupler. The plot was
calibrated and normalized using a short circuit at the far end of the test cable. Return Loss is the same
as measuring VSWR, just expressed differently. For comparison to vswr --- -14 dB RL ==> 1.5:1
vswr, -10 dB RL ==> 2.0:1 vswr, & -6 dB RL ==> 3.0:1 vswr.
The Diamond X50NA return loss was measured and showed an excellent match with a minimum return
loss of -32 dB at 448 MHz. It was better than -14 dB from 436 to 453 MHz and better than -10 dB
from 426-455 MHz.
73 de Jim, KH6HTV, Boulder, Colorado
=========================================================================
ANTENNAS - AMPLIFIERS
model 70cm23WB11
This is a NEW antenna from Serbia. We
originally reported on it in our December, 2023
ATV newsletter, issue #149. Colin, WA2YUN,
had found it while surfing the internet. He
purchased one for evaluation and kindly let us test
it.
Bottom Line ---- This is an excellent antenna.
Very rugged construction. Very well documented
with very detailed specs. on their web site.
TV Rptrs Rptr-152.doc ( 1/10/24, kh6htv) p. 9 of 13
https://antennas-amplifiers.com/dualban ... 0cm23wb11/
Plus, their specs. are accurate. We found that it really does meet spec. for gain. They claim 8.1 dBi
for 70 cm band and 11.4 dBi for 23 cm band. Here is what we measured:
70 cm Band 423 MHz 429 MHz 435 MHz 441 MHz 447MHz
Gain 8.8 dBi 7.9 dBi 7.2 dBi 7.2 dBi 7.6 dBi
23 cm Band 1243 MHz 1255 MHz 1267 MHz 1279 MHz 1291 MHz
Gain 10.7dBi 11.8dBi 12.1dBi 12.2dBi 11.0dBi
We also measured the Return Loss for this antenna and found it to be extremely well matched across
both the 70 and 23 cm bands. note: -14dB RL ==> 1.5:1 vswr, -10dB RL ==> 2.0:1 vswr
Return Loss fo (MHz) RL(fo) > 14 dB RL > 10 dB RL
70 cm Band 432 -39dB 417-437 MHz 411-455 MHz
23 cm Band 1281 -35dB 1220-1317 MHz NA
We feel this is an excellent antenna for any ham wanting a yagi for both bands. It would be ideal for
ARES groups as an addition to their ATV pac-sets for out in the field, portable operations.
Plus this antenna is definitely not a wallet buster. It's price is 139 € (Euros).
73 de Jim Andrews, KH6HTV, Boulder, Colorado
=========================================================================
Computer Control of the
Hi-Des HV-110 Receiver
John Kozak, K0ZAK
I'm still in the testing phase here for rebuilding one of the local repeaters. I was in the need for some
sort of remote receiver I could set up anywhere and control it remotely.
I wanted to use the Hi-Des HV-110 receiver but needed to figure out a way to remotely control it.
(controlled via IR remote only as you know) While Calvin at Hi-Des says it is somewhat controllable
via onboard pins, he didn't go into detail and I didn't want to engineer a way to do that.
I'm using a microPC running Win11 (more on that later) connected to the internet for control.
TV Rptrs Rptr-152.doc ( 1/10/24, kh6htv) p. 10 of 13
Standard Hi-Des HV-110 for receiver. Cheap USB connected relay board for powering HV-110 on &
off, as well as changing bandwidth switch between wide & narrow settings as I am still testing 6 MHz
vs 2 MHz bandwidth on range and quality.
Software called IRCommand2 that allowed me to create a GUI version of the Hi-Des remote control.
The Lite license for $10 was all that was needed to do what I needed rather than the more expensive
full license.
I was hoping to use one of the many old MCE IR dongles I had laying around from my old Microsoft
Media Player days. Software has a special driver written for these. HOWEVER, no go. I got an
immediate response from the software author after I e-mailed him from his contact button on the
webpage. Turns out that Microsoft just broke the MCE drivers in one of the latest Win 11 updates, and
since they abandoned Microsoft Media Player a while back, aren't interested if fixing it. Everything
would still work if I was running Win 10 however. He suggested I purchase a USB-UIRT module
which he still uses for his software updates. I ordered that and it works fine.
I then ran the HV-110 HDMI output through a HDMI Splitter to feed both the local monitor and the
MicroPC via a USB dongle. The hardest part was capturing the actual IR signals and setting up the
GUI buttons. The remote uses NEC1 IR protocal but the software wants RAW ir info. So I ended up
capturing the NEC codes and converting them to RAW then editing my buttons manually.
With this setup, I can remotely control and change all of the functions of the Hi-Des HV-110, power it
on and off, even upgrade its firmware if I'm brave enough :). Oh yea, I also stream the HV-110 output
from the microPC using VDO-Ninja so I can monitor the video without even logging in to the
MicroPC.
Next is to try to replicate this using a Raspberry Pi and not tie up my MicroPC. But for now, this will
do. I'm more comfortable with windows anyway.
I hope this will prove useful to someone in case they want to remotely control their HV-110 receivers.
It took me a few weeks of head scratching to get all of the IR stuff working correctly.
73 de John Kozak, , K0ZAK, Reisterstown, Maryland
TV Rptrs Rptr-152.doc ( 1/10/24, kh6htv) p. 11 of 13
Silent Key - N0OUW
To all BCARES, LARC & BARC Members:
It is with a very heavy heart that I inform you of the passing of
Jerry Schmidt this morning (January 4th). He was at the hospital
undergoing a medical procedure when he passed.
Jerry was the epitome of a “Gentle Giant” and his commitment to
BCARES and the communities he served will surely be missed.
Allen Bishop, K0ARK
BCARES Chairman & Emergency Coordinator
TV Rptrs Rptr-152.doc ( 1/10/24, kh6htv) p. 12 of 13
FEED-BACK:
ESA-AMSAT --- Hello Jim -- best wishes for 2024 from Germany and many thanks for your ATV
newsletter. that is my best source remaining for our german ATV webpages !
One correction is needed for your most recent newsletter, issue #151, as you can see in the attached
picture name from it: -- The person in front of the camera is not PD0AP from ESA, but Graham,
G3VZV, from AMSAT-UK and BATC...
73 Klaus Kramer, DL4KCK, Cologne, Germany
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:
https://kh6htv.com/application-notes/
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: https://batc.org.uk/live/ 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: https://kh6htv.com/newsletter/
ATV HAM ADS -- 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-152.doc ( 1/10/24, kh6htv) p. 13 of 13

https://kh6htv.files.wordpress.com/2024 ... -152-1.pdf
s58ru
 
Prispevkov: 1051
Pridružen: 28 Okt 2004, 21:07

Re: revija ATV

OdgovorNapisal/-a s58ru » 24 Jan 2024, 10:21

s58ru
 
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Pridružen: 28 Okt 2004, 21:07

Re: revija ATV

OdgovorNapisal/-a s58ru » 02 Feb 2024, 09:15

s58ru
 
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Pridružen: 28 Okt 2004, 21:07

Re: revija ATV

OdgovorNapisal/-a s58ru » 15 Feb 2024, 00:05

s58ru
 
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