This is frequency shift keyed picture transmission mode developed and used by the amateur radio community. While these signals are FAX-like in function they do not possess the scratching quality of HF FAX signals. The sound of an SSTV signal is more tonal or musical in nature.
There are several types of modulation scheme used. The most popular is called Martin 1, but Scott 1, SC2 180 and Robot 72 are also used. The sample above is a Martin 1 signal decoded using Bonito RadioCom software on a PC and an AOR AR-7030 receiver tuned to the 14MHz amateur band.
