Slow-Scan Television (SSTV)

SSTV is something I'm interested in lately basicly it is a picture transmission method used mainly by amateur radio operators, to transmit and receive static pictures via radio in monochrome or color.

These image types could be GIF, JPG, BMP or similar depending on the computer software used for the SSTV transmissions. It works similar to Facsimile transmissions. Each colour has it's own frequency in SSTV mode and the software simply codes the colour into an audible frequency tone that can be interfaced into the microphone system of the radio. The receiving end software simply decodes the frequency tone back into the colour.

A technical term for SSTV is narrowband television. Broadcast television requires huge 5, 6 or 8 MHz wide channels, because it transmits 25 or 30 pictures per second (in the NTSC, PAL or SECAM systems), but SSTV usually takes up to only 3 kHz of bandwidth. It is a much slower method of still picture transmission, usually lasting from about eight seconds to a couple of minutes.

Since SSTV systems operate on voice frequiencies, amateurs use it on shortwave (also known as HF by amateur radio operators),VHF and UHF radio.

Anyone can receive SSTV, you don't need a ham licence. All you need is a receiver, software for your PC (FREE HERE) Digital Master 780 & MMSSTV are excelent, and you connect the audio out from the receiver to the sound card on your PC, Interface infomation HERE.You will then be able to pick up SSTV from all over the world.

Dx stations like to send pictures as a sign of making the contact. Because the images are easily stored, the picture itself becomes the QSL "card". They generally send a picture of the operator and the station, often with the call of the contacted station being type onto the image. I find foreign stations generally very interesting, as they often have neat scenery shots from around their country.

Experimenters use SSTV to send pictures of the latest project. They can then describe what they are doing and send closeups of the unit. A technical discussion then results in several picture interchanges and everything is stored for future reference. The amateur SSTV differs from an Internet technical discussion as a dialog differs from a monolog.

The most interesting SSTV contacts occur when amateurs have a QSO about common interests. I like antenna experimentation, flying R/C airplanes and Astronomy.

"Local" SSTV QSOs are the most common QSOs, just like in the rest of amateur radio activities. I define "Local QSO" as a conversation with an amateur that is one of many conversations. A great number of pictures are required to keep local QSOs interesting. The pictures must be personally interesting or others will not find them interesting either.

Roundtable QSOs and SSTV Nets are particularly difficult to maintain an interesting chain of audio and visual intercommunication. A good unifying topic goes a long way towards maintaining an interesting multi-party QSO.

If your interested in this you can find more information here:

http://www.sstvham.com/

http://www.qsl.net/g4zer/