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Last modified 2012-12-29

ATV (Amateur TeleVision) in Stockholm

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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?

CallsignNameQTHMain equipment
SA0AWSPeterSpångaComtech RX & TX modules. 18 W PA. 23 element Tonna
SM0OFVJanneSolnaComtech RX & TX modules. 16 W PA. 23 element Tonna
SM0WLLUffeBotkyrkaComtech RX & TX modules. 18 W PA. 22 element M2

There are a couple of other hams in different stages of getting QRV as well, plus a few others unrelated to us, whose whereabouts are unknown.

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.

Time and frequency

For simplex contacts, we use 1255 MHz with vertical 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.

Reporting system

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

PS/N ratioPicture quality
P5>45 dBThe picture has no discernable noise. Excellent reception!
P435-45 dBThe picture is very slightly noisy. Fully acceptable reception
P320-35 dBThe picture is somewhat noisy
P28-20 dBThe picture is definitely noisy. Finer details are lost
P13-8 dBThe picture is very noisy and barely recognised.
P0<3 dBOnly some sync bars may be seen, no actual 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 .


SM0OFV equipment, front

SM0OFV equipment, inside

SM0WLL received by SM0OFV

SM0WLL received by SM0OFV

SM0WLL equipment, front/back

SM0WLL equipment, inside

SA0AWS received by SM0OFV

SA0AWS equipment, front

More to come...