Long range image radio transmitter

Slow scan television (SSTV) image transmission system is used by many decades by radio amateurs. There are numerous modes, some for B/W others for color images. We choose the Robot36[1] mode because it is transmitting color images and because is widely used. Usually this requires a PC to capture and process the data to get the audio signal necessary for transmission. In recent years the development of low cost embedded platforms open the possibility to replace the large PC with a small ARM boards to do all the video capture and single processing. In this case we used on of the cheapest model: Raspberry PI. For signal modulation and radio transmission, a miniature solution was developed using parts commercially available. The transmitter runs on 433.8MHz, output power 1.5W, and uses narrow band FM modulation, as the SSTV standard requires. Because of the small size relative to dissipate power, heat dissipation was carefully investigated. On the image was overlaid the data taken from GPS as an “on screen display” (OSD).