Slow Scan TV (SSTV)
What is SSTV?
SSTV (or Slow Scan Television) is a way of transmitting still pictures over the air. Because it takes a period of a minute or two to build up the picture it does not take up very much bandwidth and so can be done over HF, as opposed to FSTV (Fast Scan Television – moving pictures) which takes up a much larger bandwidth and usually only takes place on VHF and up frequencies.
How does it work?
Pictures are built up line by line. When you listen to an SSTV signal you will will hear a regular click which tells the software where to start drawing the next line of the picture. Inbetween there is a series of tones that represent the various colours. To the right is a video of an SSTV signal being received.
Where do I start?
All you need to get going initially is to download the SSTV software. There are a couple of choices with MMSTV being the most popular. The one I use is call YONIQ, which is based on MMSTV but with some extra abilities built in. You can download them by clicking
- MMSTV – or
- YONIQ – You might like to take a look at the YONIQ Website.
Once downloaded and running, the simplest thing to do is to try some SSTV reception. To see it in operation you can just use you PC microphone to pick up the audio from your radio, which will certainly work. Ideally though you would run the audio from your radio directly into the soundcard of your computer. When you are ready for transmitting, then you will also need to send audio from you PC directly to your radio for a clean transmission.
SSTV Frequencies
| Wavelength | Frequency | Mode |
|---|---|---|
| 160m | 1.890 & 1.924 | LSB |
| 80m | 3.730 | LSB |
| 40m | 7.033, 7.040 , 7.165 & 7.171 | LSB |
| 30m | 10.132 | USB |
| 20m | 14.230 - 14.240 | USB |
| 17m | 18.117 | USB |
| 15m | 21.340 | USB |
| 12m | 24.927 & 24.940 | USB |
| 10m | 28.260 & 28.677 | USB |
| 6m | 50.680 FM & 50.950 USB | |
| 2m | 144.500 FM & 145.550 USB & 145.600 FM & 145.800 FM (ISS downlink) | |
| 70cm | 430.950 | USB |
Digital SSTV
There some programs out there that will allow for Digital SSTV, which result in excellant quality images. I have not looked into this closely, but will report back here when I find out more! The digital SSTV program ‘Easypal’ can be found HERE!
Digital SSTV Frequencies
| Wavelength | Frequency |
|---|---|
| 80m | 3.733 |
| 40m | 7.058, 7.165 & 7.171 |
| 20m | 14.233 |
| 15m | 21.337 |
Below are some SSTV images taken from the ISS space station.
