Slow scan television, SSTV, is the mode that lets you send an actual picture over radio instead of text or voice. It’s been part of amateur radio since the 1950s, and it’s still active today, helped along by regular SSTV transmissions from the International Space Station.
How a radio signal becomes a picture
SSTV encodes an image by scanning it line by line and converting brightness and color information into audio tones, the same basic soundcard-in, soundcard-out approach FT8 and PSK31 use, just decoding to a picture instead of text. A single image typically takes anywhere from about 8 seconds to several minutes to transmit depending on the SSTV mode and resolution chosen, which is exactly where the slow in slow scan comes from.
What you actually need
If you already have a digital mode setup, a radio, a sound card interface, and a computer, you have almost everything you need. Software like MMSSTV, EasyPal, or the SSTV modes built into some multi-mode digital suites handle the encoding and decoding. On HF, SSTV activity tends to cluster around 14.230 MHz on 20 meters, and on VHF, local SSTV nets exist in some areas, though they’re less common than HF activity.
The ISS connection
Periodically, the International Space Station transmits SSTV images on 145.800 MHz as part of scheduled commemorative events, and receiving one of those images with nothing more than an HT and a decent antenna is a genuinely fun way to get a taste of what SSTV can do without needing to build out a full station for it first. It’s a low-commitment way to try the mode before deciding whether you want to make it a regular part of your operating.
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