SSTV is sent in both analog and digital modes. I primarily focus on transmitting in analog mode using the program MMSSTV. The program uses the computer's soundcard to generate the SSTV audio tones which is fed into the microphone input of an HF transceiver. It also uses the soundcard to decode the incoming signal. In analog SSTV, the different audio tones are used to make the different colors in the SSTV picture. Black video corresponds to an audio tone of 1500 Hz while white is sent at 2300 Hz. Grey is sent anywhere between these two frequencies, and color images are sent by sequentially sending the red, green, & blue pulses, depending on the SSTV mode used. There are numerous different SSTV modes in use, but the most common modes sent are Scotty 1 and Scotty 2. The program MMSSTV has the capability to send & receive various different modes.
To interface with my HF transceiver I use the homebrew interface I built for PSK31. The MMSSTV program uses the same CTS line in the serial port to key the radio, so the interface works well with both programs.
When I first got on SSTV, I didn't have many digital photos to send but did find some on the internet. However, later I bought a digital camera so am able to take my own pictures and transmit them over the air.
Using the MMSSTV program, one is able to add their own text in the form of templates over existing pictures. The picture at the top of the page is one picture I use as a CQ picture. I added the text over an picture of an old test pattern.
The most popular SSTV frequency is 14.230 MHZ. SSTV can also be found on 40 & 80 meters.