PICCOLO Mark VI

British Foreign and Commonwealth Office (FCO) designed system based on sending 2 of 6 tones in sequence for ITA-2 and 2 of 12 for ITA-5 for each character to be sent. Idle condition is tones 5 and 6 sent sequentially. These two tones are also the two centre tones thus making tuning easy when the station is in standby. Two user baudrates of 50 and 75 Baud are possible but the on-air speed remains constant due to the use of inserted idlers for 50 Baud.

Tones used are No. 3 to 8 at 20 Hz apart for ITA-2 Baudot (Most common)

No. 0 to 11 at 20 Hz apart for ITA-5 ASCII (Very rare)

Piccolo's usually reside on 510, 910, 1310 and 1710 Hz offsets from a carrier point. Most often in USB. 510 will nealry always be the engineering channel and be idle for long periods of time. The 910 Hz channel is nearly always keying crypto traffic and is referred to as the Data channel.