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?
| Callsign | Name | QTH | Main equipment |
|---|
| SA0AWS | Peter | Stockholm | 23 cm: Comtech RX & TX modules. 18 W PA. 23 element Tonna (QRT!) |
| SA0AZS | Carl-Michael | Stockholm | 23 cm: Under construction. Comtech RX & TX modules. 18 W PA. (Development halted!) |
| SA0BDC | "Rulle" | Södertälje |
Analog (FM-ATV)
23 cm: Comtech RX & TX modules. 140 W PA. 2*64 elements
DATV ((DVB-S/S2)
70 cm: TX: ADALM Pluto, RX: Minitiouner Express |
| SA0BDK | Anders | Huddinge |
DATV ((DVB-S/S2)
70 cm: TX: ADALM Pluto, RX: Minitiouner Express |
| SA0CCA | Anders | Huddinge |
Analog (FM-ATV)
23 cm: Comtech RX & TX modules. 60 W PA. 2*44 elements
DATV ((DVB-S/S2)
70 cm: TX: ADALM Pluto, RX: Minitiouner Express |
| SM0IFL | Åke | Lidingö |
DATV ((DVB-S/S2)
70 cm: TX: SDR, RX: SDR with SDR Angel software |
| SM0OFV | Janne | Solna |
Analog (FM-ATV)
23 cm: Comtech RX & TX modules. 16 W PA. 23 element Tonna
13 cm (2.4 GHz): Comtech RX & TX modules. Max 100 mW (as allowed in Sweden). WiFi mesh antenna
6 cm (5.7 GHz): Drone modules. 1.5 W. 18 dBi panel antenna
3 cm (10 GHz): TX: HB100 DRO module and homebrew modulator. RX: Modified PLL LNB and Comtech module
DATV ((DVB-S/S2)
70 cm: Portsdown 2019 and Portsdown 4. TX: Filter modulator and LimeSDR Mini. RX Minitiouner v2, PicoTuner & Minitiouner Express |
| SM0VPJ | Janne | Sollentuna |
Analog (FM-ATV)
23 cm: Comtech RX & TX modules. 18 W PA. 23 element Tonna
13 cm (2.4 GHz): Wireless camera modules. Max 100 mW (as allowed in Sweden). WiFi antenna
6 cm (5.7 GHz): Drone modules. 300 mW. 20 dBi panel antenna
3 cm: (10 GHz): TX: HB100 DRO module and homebrew modulator. RX: Modified PLL LNB and Comtech module
DATV ((DVB-S/S2)
70 cm: Portsdown 4. TX: LimeSDR Mini. RX: PicoTuner & Minitiouner Express |
| SM0WLL | Uffe | Botkyrka | 23 cm: Comtech RX & TX modules. 18 W PA. 55 element Tonna |
| SM0YCD | Robert | Barkarby | 23 cm: Under construction. Comtech RX & TX modules (Development halted!) |
| SM0YHL | Göran | Tullinge | 23 cm: Under construction. Comtech RX & TX modules (Development halted!) |
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.
2.4 GHz (13 cm)
SM0VPJ and I are QRV on this band with max 100 mW input to the antenna system. Sadly, this power limit was invoked by the swedish authorities
in the nineties (or possibly the late eighties). This of course means a limitation in the general range, but with line-of-sight and decent antennas, the
range can be quite usable.
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.
10 GHz (3 cm)
In the spring of 2020, SM0VPJ and I performed local tests of modified, existing electronics for use in this band. Picture quality was found to be
excellent. Range tests and 2-way QSO are on our agenda for the summer of 2021. We will however not be able to have this equipment fully ready
for the 2020 IARU Region 1 ATV Contest.
Reporting system
The usual S-report system does not apply. Instead, the P-system (for picture quality) is used.
| P | S/N ratio | Picture quality (analog) | Digital equivalent |
|---|
| P5 | >45 dB | The picture has no discernable noise. Excellent reception! | Solid picture |
| P4 | 35-45 dB | The picture is very slightly noisy. Fully acceptable reception | Occasional blocking |
| P3 | 20-35 dB | The picture is somewhat noisy | Some blocking |
| P2 | 8-20 dB | The picture is definitely noisy. Finer details are lost | Sufficient blocks to read callsign |
| P1 | 3-8 dB | The picture is very noisy and barely recognised. | Only occasional blocks visible |
| P0 | <3 dB | Only some sync bars may be seen, no actual picture | No 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 |
SM0OFV R1 ATV Contest 2020 |
SM0VPJ R1 ATV Contest 2020 |
Contest 2020 rover certificate |
Contest 2020 Sweden certificate |
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