SLOW SCAN TV By Harvey Easton K7UQ  |
Slow scan TV or as it is commonly called SSTV is a legal way for ham radio operators to send pictures to each other using narrow bandwidth audio frequencies to convey the video information. Not to be confused with Fast Scan TV, Slow Scan Television (SSTV) was invented back in the 1960's and became popular on the amateur bands in the mid-1970's. Slow Scan TV utilizes audio tones ranging from 1200hz to 2300hz to paint a still-frame picture utilizing standard amateur voice bandwidths. Anywhere you can transmit your voice, you can transmit a SSTV picture (AM, FM, or SSB). In the early days SSTV required specialized equipment costing hundreds or even thousands of dollars. With the advent of personal computers it has become very easy and inexpensive to operate SSTV. To receive the pictures, we use a computer program that hears the audio frequencies and transforms them into video pictures we view on our computer monitors. The common resolution that we see on our monitors is 320X256 bits. A common resolution we use with our video cameras is 640 X 480 bits. The enclosed pictures will give you an idea of how well you can view the pictures. So far here at the K7UQ ham shack, I have not sent any pictures, but in sending picture I would use the same program I use for receiving to send the pictures. The program would read a stored photo and transform that image into digital sounds I would transmit on usb. The sound of the SSTV pictures is similar to rtty or psk31. Kind of a dweedle dweedle sound. What program should I use, and where do I find it? Got the program downloaded and installed on computer. Now what? Related Links |