Murphy, GM3SBC, and Martin Emmerson, G3OQD, who wanted to make color SSTV less prone to interference. The amount of sync signals was reduced, so the pictures are transfered nearly running free. To realise slow scan operation you can take special SSTV devices with all functions and interfaces for storing and transfering pictures, or you take your home computer. With this and various available special software and different converter types the expenses are relatively small. At the same frequencies there are meeting FAX friends too, collisions and misunderstandings can be prevented if you announce your mode before transmitting.
Facsimile telegraphy is one of the oldest telegraphy modes.
Practical use of that followed much later. After 1920 the picture telegraphy was developed further in USA and Europe by well known companies like RCA, Bell, Muirhead, Siemens and Hell until todays photo telegraphy in black and white or even in three color extracts transfered one after another. Functioning With classic style facsimile transmission a paper sheet is scanned by a light beam generating an electrical signal in amplitude modulation. The sheet is scanned on a rotating drum line by line similar to television. The picture signal is modulated onto a sound subcarrier and demodulated at the receiving end.