FSK2001000

This mode is believed to be used by the Russian intelligence services. Data is transmitted using FSK (Frequency Shift Keying) at a speed of 200 baud with a 1000 Hz shift.

FSK200/1000 messages are transmitted with fixed schedules on frequencies which change monthly. The latest information on the times and frequencies of these schedules can be found online here.

There is a WAV file recording of a FSK200/1000 signal on the Rivet sound samples page here.