Chayka (Russian: Чайка, lit. "seagull") also known as Radiotekhnicheskaya Sistema Dal'ney Navigatsii abbreviated as RSDN (lit. Radio-technology System for Distant Navigation) is a Russian terrestrial radio navigation system, similar to Loran-C. It operates on similar frequencies around 100 kHz, and uses the same techniques of comparing both the envelope and the signal phase to accurately determine location. The systems differ primarily in details.
Chayka, like LORAN-C, uses different pulse repetition frequencies (Group Repetition Intervals, or GRIs) to allow the identification of different stations operating on the same frequencies.
There are 5 Chayka chains in use:
GRI 8000 — Western (European) Russia Chayka Chain (1969, RSDN-3/10)
GRI 7950 — Eastern Russia Chayka Chain (1986, RSDN-4)
GRI 5980 — Russian-American Chayka Chain (1995)
GRI 5960 — Northern Chayka Chain (1996, RSDN-5)
GRI 4970 — North-Western Chayka Chain
And also North-Caucasian, South-Ural (GRI 5970), Siberian, Angarsk, Sayansk, Transbaikalian, Far East chains deployed on the basis of low-power mobile stations RSDN-10.
Chayka Transmitters
The following Chayka transmitters work with very high power and may use very tall mast antennas (similar to LORAN-C transmitters). The masts at Dudinka and Taymylyr (demolished in 2009) were 460 metres high.
