Don't be fooled by the fact that today's SSTV is completely managed by software, the only thing that truly defines SSTV is *modulation*. SSTV is the acronym for Slow Scan Television - It's about a way of transmitting still pictures by analog frequency modulation and *not* a digital mode. SSTV was conceived to send images over a narrow bandwith, despite some technical limitations that won't allow transmission of moving pictures like commercial TV broadcasters. To keep it short (and simple), as this kind of transmission would take about 5 MHz bandwidth or more it's not suitable for amateur radio communications across the HF spectrum where we must contain our emissions within kHz, not MHz. In old analog fast scan television broadcasts, TV towers used to transmit rasterized pictures (frames) at a given frame rate as television cameras would run continuous and interlaced scans of the scene consisting of 525 or 625 lines per second, depending on the standard adopted. As too many websites have been built around this topic, should you need additional details you may easily refer to them, while the purpose of *this* website instead is to introduce you to the pragmatic aspects of this branch of ham radio communications. The photo I used for this demo is a picture of my brother Bob who was killed in the Navy in 1953.It is not my intention to spend a million words on SSTV, as tons of technical pages have already been written and today they are available on the Internet. This video was then mixed with sync pulses for tranmission. For transmitting I built a flying spot scanner which used a 3 inch CRT to bounce light off a picture. The first monitor I built had a 5 inch screen and later I built a 7 inch all transistor monitor. Usually 3 frames were sent during a transmission. The yellow appearance is from a yellow filter in front of the display to reduce the blue light caused when the beam hit the yellow phosphor. The 8 second black and white image was displayed on a P7 CRT used in radar sets. This is what the first SSTV images looked like about 1960. Erik VK4AES author of EasyPal digital image software.
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