CROWD36 A Soviet MFSK system using 36 tones based on British Piccolo MK1. CIS Diplo service is the main user with suspected use by CIS Intel and Military services. This

system is found at 40 bd with a single tone lasting 25ms. Hand keyed traffic is usually 10 bd with a single tone lasting 100ms. A spectrum analyzer will show the

tones arranged in 3 distinct groups of 10+11+11 tones.

Tones are spaced 40Hz apart and tones 1, 12, 24 and 36 are rarely used so you are likely to see an 80Hz gap between groups. Each of the 32 tones represents one

ITA2 character code.

Also known as CIS/Russian Piccolo, URS multitone, CIS-10-11-11 MFSK or CIS-36. As of this date there are NO publicly available decoders for this system although

they do exist in the professional market. Some decoders available NOW provide tools that can be used to demodulate the tones and from there derive a character set. One such method is covered below.

ITU documents have listed 4 different kinds of CROWD36 that vary with tone duration and baud speed. The '*'entries below are commonly heard.

 +----------- tone duration (ms)

| +------- shift between tones

| | +--- tones present signal

v v v

Russian Piccolo 1 25 40 34 * 40bd

2 25 10 34

3 100 40 34 * 10bd

4 100 10 34

A few distinct patterns can be detected in a CROWD36 signal: selcal, idling and sending traffic. Selcal and idling are a series of 5 tones repeated in the same pattern. Traffic mode is most commonly, but not always, found as 40bd encrypted and many times operator traffic can be found in the clear at 10bd. Start-up and sign-off are usually 10bd and hand keyed.

Demodulation/Decoding

To correctly zero a CROWD36 signal is difficult. The signal is asymmetric so don't use the center of the middle tone group. Tones are only shifted by 40Hz and tuning errors as small as +-5Hz will start to induce errors.

From the raw tone sequences use the table in Table 5-J to map the tone number to character.

Mazielka A SELCAL system used by the "brotherhood" stations to wake up the receiving station operator outside normally scheduled transmissions. Reported to be part of the

CROWD36 system outlined above. It is composed of 6 tones out of a tone library of 13. See WUN Special Edition, V1.3, Apr '95 for a good explanation of the system and its uses.