GettingStartedwithSlowScan.PDFVIP

Getting Started with Slow Scan Television QST September 1990, pp. 53-56 Copyright ? 1997 by the American Radio Relay League, Inc. All rights reserved By Ramon L. Glidden, W5NOO Getting Started with Slow Scan Television Who says hams should be heard and not seen? hink of all the methods hams use to communicate with We’ve Come a Long Way each other. The short list would include speech, data About 28 years ago I constructed a slow-scan monitor based on and Morse code. Did you forget images? At 420 MHz a design by Cop McDonald, WA2BCW, that was published in the T and up, hams routinely exchange live, full-motion March 1964 QST (“A Compact Slow-Scan TV Monitor,” p 43). video. It’s called fast-scan television (FSTV)—the same TV State-of-the-art SSTV back then consisted of a tiny green screen you’re accustomed to seeing at home. FSTV is a fun mode, but the that “painted” an image every eight seconds. The viewing wasn’t transmitted range is limited to a few hundred miles under the best easy. By the time the last line was painted at the bottom of the conditions. In addition, special transmitters and receivers are screen, the lines at the top were fading! And there was no way to required. save these old images other than to take time-exposure photo- But what if you wanted to share images over thousands of graphs or make audiotape recordings. miles? You could take a fixed (nonmoving) image and slowly scan Today I enjoy sending and receiving high-quality, 16-million- it line by line, converting the color and brightness variations into color SSTV pictures—some even in 3D!—and have hundreds audio tones. Feed the audio tones to an ordinary SSB voice trans- stored on my computer. I can watch them appear on my monitor ceiver and you can send this informati