суббота, 10 октября 2009 г.

FSK: Russian native Airforce "Chayka" - telecode "Chayka"

Russian Airforce "Chayka" - telecode "Chayka"
Command/short message system, crypto, FSK-2.

Author: SergUA6
Band Width ~ 600 Hz
Low Range ~ 500 Hz, shift is possible, recieveing in SSB
Baud Rate 75, 150, 300, 1200 Hz
Count of Carriers 2 well visible frequency of manipulation on speed in 75Hz, but on 150-300Hz it will be problematic
Step between carriers 500 Hz
RX mode SSB


pic.1 General view

pic.2 Speed of manipulation

pic.3 The repeated fragment


pic.1 The exact frequency spacing

Russian Airforce "Chayka" - One of native Russian systems (equipment "Chayka") of interactions of military air forces and land stations.
It is old enough system, is probably still used today, because the transmission is encrypted and it is hard enought to identify it with high level of reliability.

An implicit signs of this system: the preamble presence, an alternation of tones with frequency of manipulation in the beginning, and also rare enough rating of frequencies 500 Hz. There is well visible presence of the repeating part, which is aldo vegin from the short preamble, on the third sonogram . Speed is 1200, it is most likely used on VHF a range (usual practice), other speeds are used for connection on HF. Sea-gull is the English translation for Russian word "Chayka:'.