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Last modified 2020-01-21

ATV (Amateur TeleVision) in Stockholm

klicka här för en svensk version, eller här för IARU Region 1 ATV Contest slutresultat.

What is ATV?

ATV (Amateur TeleVision) has nothing to do with the four wheel terrain vehicle. No, it's simply a method of communication with
live, moving video and sound, just like a normal TV channel. ATV is sometimes also called FSTV (Fast Scan TeleVision).

ATV in Sweden

In Sweden, ATV is almost non-existant for unknown reasons. However, located in the Stockholm area, we are a very small group
of active ATV enthusiasts.

We use partially homebrew and home assembled equipment for analog FM-modulated video and stereo audio in the 23 cm band.

We used to transmit via an ATV-repeater in the Kaknäs tower, but the repeater was sadly decommissioned without any explanation
back in 2010. We are however still active on simplex with some minor limitations.

Who is actually QRV here in Stockholm area?

CallsignNameQTHMain equipment
SA0AWSPeterStockholm23 cm: Comtech RX & TX modules. 18 W PA. 23 element Tonna
SA0AZSCarl-MichaelStockholm23 cm: Under construction. Comtech RX & TX modules. 18 W PA.
SA0BDC"Rulle"Södertälje23 cm: Comtech RX & TX modules. 140 W PA. 2*64 elements
DATV under construction. TX: ADALM Pluto, RX: Minitiouner Express
SA0BDKAndersHuddinge23 cm: Reception trials with analog sat receiver and colinear vertical
DATV under construction. TX: ADALM Pluto, RX: Minitiouner Express
SA0CCAAndersHuddinge23 cm: Comtech RX & TX modules. 60 W PA. 2*44 elements
DATV under construction. TX: ADALM Pluto, RX: Minitiouner Express
SM0OFVJanneSolna23 cm: Comtech RX & TX modules. 16 W PA. 23 element Tonna
6 cm (5.7 GHz): Drone modules. 1.5 W. 18 dBi panel antenna
DATV under construction. TX: Portsdown 2018 & 2019, RX: Minitiouner v2 & Minitiouner Express
SM0VPJJanneSollentuna23 cm: Comtech RX & TX modules. 18 W PA. 23 element Tonna
6 cm (5.7 GHz): Drone modules. 300 mW. 20 dBi panel antenna
DATV under construction. TX: Portsdown 2019, RX: Minitiouner Express
SM0WLLUffeBotkyrka23 cm: Comtech RX & TX modules. 18 W PA. 55 element Tonna
SM0YHLGöranTullinge23 cm: Under construction. Comtech RX & TX modules

Equipment

Most of our equipment consists of Comtech RX and TX modules, which are pretty cheap to buy and easy to assemble. Since the TX
has a measly 50 mW output, we also have separate power amplifiers to raise the output to something between 15-20 W. We all use
multi-element yagis with at least 15 dBd gain, which has proven to be quite sufficient for simplex contacts between the members of
our little group.

Care must be taken when planning and installing the antenna system though. Keep in mind that this is wideband communication in our
lowest microwave band, and you must use the best feeder and connectors possible for your installation. If you fail just a little bit in this
department, then you'll probably not see much, and maybe no one can see you.

See also this area for some usable hardware.

Both video and audio is FM-modulated, just like analog satellite TV transmissions. In fact, an old analog satellite receiver may be the very
first step into receiving ATV-signals in the 23 cm band. It should however be noted that these units are fairly deaf as they are intended to
be connected to a powerful LNB in a satellite dish. A good preamp is therefore needed unless you're watching fairly strong signals.

Much of the early ATV-equipment for 23 cm used AM-modulated video, but the more modern FM-video means higher video quality.

Interference

Some time around the winter 2014-2015, SM0WLL started having big trouble receiving my transmissions. I myself experienced some
interference on his too, but not as serious. Well, after some investigation it stood clear that the problem was the ever expansion of cellphone
base stations. To clarify, the Comtech receiver modules are broadband devices, capable of receiving from below 900 up to over 2000 MHz.
The 23 cm band covers 1240 to 1300 MHz in most countries. Now, if you have a powerful cellphone base station nearby, transmitting on, say
900 or 1800 MHz, the risk for your receiver being seriously affected or even totally blocked is very high.

So, what can we do about this? Well, a bandpass filter tuned for the 23 cm band will do the trick for sure. When inserted before the receiver at
SM0WLL's site, my picture when from barely visible through the interference to full "studio" P5 quality! Such filters can be homebrewed or
purchased from online vendors. A good ready-built filter from Germany will set you back about 50 to 55 Euro. This is money very well spent.

Time and frequency

For simplex contacts, we use 1255 MHz with horizontal polarization. We are mostly QRV late in the evenings. If you want a sked on ATV, then
try calling any of us on 144.750 MHz FM (ATV Talkback) or on the R6x repeater.

5.7 GHz (6 cm)

Since april 2016, I (SM0OFV) am also QRV on the 6 cm band (5.7 GHz). The equipment consists of transmitter and receiver units built for
R/C models, mainly drones, helicopters and planes. This type of equipment is very cheap and easy to use.

Among my 5.7 Gig stuff is a 1.5 W transmitter and a diversity receiver. For the moment I use these while out and about i.e. "hilltopping".
If future circumstances allow, I will also install fixed gear at home. As of july 2019, SM0VPJ is also QRV on this exciting band.

Reporting system

The usual S-report system does not apply. Instead, the P-system (for picture quality) is used.

PS/N ratioPicture quality (analog)Digital equivalent
P5>45 dBThe picture has no discernable noise. Excellent reception!Solid picture
P435-45 dBThe picture is very slightly noisy. Fully acceptable receptionOccasional blocking
P320-35 dBThe picture is somewhat noisySome blocking
P28-20 dBThe picture is definitely noisy. Finer details are lostSufficient blocks to read callsign
P13-8 dBThe picture is very noisy and barely recognised.Only occasional blocks visible
P0<3 dBOnly some sync bars may be seen, no actual pictureNo picture

Pictures

Please note that the off-air photos does not do reality any justice.
It's difficult to take good pictures of a flickering TV screen .

Click to enlarge...


SM0OFV equipment - 2010

SM0OFV equipment - 2010

SM0WLL received by SM0OFV

SM0WLL received by SM0OFV

SM0WLL equipment - 2012

SM0WLL equipment - 2012

SA0AWS received by SM0OFV

SA0AWS equipment - 2009

SA0CCA received by SM0OFV

SA0CCA received by SM0OFV

SA0CCA equipment - 2017

SM0OFV R1 ATV 2016 certificate

SM0OFV received by SA0BDC

SM0VPJ. R1 ATV Contest 2017

SM0WLL. R1 ATV Contest 2017

SA0CCA. R1 ATV Contest 2017

SM0OFV R1 ATV 2017 certificate

SA0BDC, trial 1. P1

SA0BDC, trial 2. P5

SA0BDC, trial 3. P3

SA0BDC, trial 4

SM0OFV R1 ATV 2018 certificate

SM0OFV R1 ATV Contest 2019

SM0OFV R1 ATV Contest 2019

SM0VPJ R1 ATV Contest 2019

SM0OFV. 6 cm gear - 2019

SM0OFV. 6 cm gear - 2019

SM0OFV. 6 cm gear - 2019

SM0VPJ RX'd by SM0OFV. 6 cm

SM0OFV RX'd by SM0VPJ. 6 cm

SM0OFV RX'd by SM0VPJ. 6 cm

SM0OFV R1 ATV 2019 certificate


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