53°07′51″N 34°54′45″E / 53.13083°N 34.91250°E / 53.13083; 34.91250

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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.

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.

#	Place	Coordinates	Emission delay, μs	Coding delay, μs	Transmission power, kW
M	Karachev (44 km from Bryansk)	53°7′50.6″N 34°54′44.8″E / 53.130722°N 34.912444°E / 53.130722; 34.912444			450
W/1	Petrozavodsk	61°45′32.4″N 33°41′40.4″E / 61.759000°N 33.694556°E / 61.759000; 33.694556	13217.21	10000	700
X/2	Slonim (Belarus)	53°7′55.2″N 25°23′46″E / 53.132000°N 25.39611°E / 53.132000; 25.39611	27125.00	25000	450
Y/3	Simferopol	44°53′20.18″N 33°52′23.79″E / 44.8889389°N 33.8732750°E / 44.8889389; 33.8732750	53070.25	50000	550
Z/4	Syzran	53°17′17.6″N 48°6′53.4″E / 53.288222°N 48.114833°E / 53.288222; 48.114833	67941.60	65000	700

#	Place	Coordinates	Emission delay, μs	Coding delay, μs	Transmission power, kW
M	Alexandrovsk-Sakhalinsky	51°4′42.81″N 142°42′4.95″E / 51.0785583°N 142.7013750°E / 51.0785583; 142.7013750			700
W/1	Petropavlovsk-Kamchatsky	53°7′48.26″N 157°41′49.1″E / 53.1300722°N 157.696972°E / 53.1300722; 157.696972	14506.5	11000	700
X/2	Ussuriysk	44°31′58.24″N 131°38′28.6″E / 44.5328444°N 131.641278°E / 44.5328444; 131.641278	33678.0	30000	700
Y/3	Tokachibuto (Japan)	42°44′37.2″N 143°43′10.5″E / 42.743667°N 143.719583°E / 42.743667; 143.719583	49104.15	46000	600
Z/4	Okhotsk	59°25′1.77″N 143°5′18.68″E / 59.4171583°N 143.0885222°E / 59.4171583; 143.0885222	64102.05	61000	10

#	Place	Coordinates	Emission delay, μs	Coding delay, μs	Transmission power, kW
M	Petropavlovsk-Kamchatsky	53°7′48.26″N 157°41′49.1″E / 53.1300722°N 157.696972°E / 53.1300722; 157.696972			700
W/1	Attu Island (United States)	52°49′44″N 173°10′49.7″E / 52.82889°N 173.180472°E / 52.82889; 173.180472	14506.5	11000	400
X/2	Alexandrovsk-Sakhalinsky	51°4′42.80″N 142°42′4.95″E / 51.0785556°N 142.7013750°E / 51.0785556; 142.7013750	31506.5	28000	700

(No longer in service)

#	Place	Coordinates	Emission delay, μs	Coding delay, μs	Transmission power, kW
M	Dudinka	69°21′45.20″N 86°41′50.56″E / 69.3625556°N 86.6973778°E / 69.3625556; 86.6973778			1200
W/1	Taymylyr	72°34′48.92″N 122°06′40.29″E / 72.5802556°N 122.1111917°E / 72.5802556; 122.1111917			1200
X/2	Pankratiev Island	76°7′34″N 60°12′55″E / 76.12611°N 60.21528°E / 76.12611; 60.21528			250
Y/3	Inta	65°57′59.57″N 60°18′33.5″E / 65.9665472°N 60.309306°E / 65.9665472; 60.309306			1200

#	Place	Coordinates	Emission delay, μs	Coding delay, μs	Transmission power, kW
M	Inta	65°57′59.57″N 60°18′33.5″E / 65.9665472°N 60.309306°E / 65.9665472; 60.309306			1200
W/1	Tumanny	69°3′8.4″N 35°40′14.3″E / 69.052333°N 35.670639°E / 69.052333; 35.670639
X/2	Pankratiev Island	76°7′34″N 60°12′55″E / 76.12611°N 60.21528°E / 76.12611; 60.21528			250

#	Place	Coordinates	Emission delay, μs	Coding delay, μs	Transmission power, kW
M	Yuzhno-Uralsk	54°23.1′N 61°20.6′E / 54.3850°N 61.3433°E / 54.3850; 61.3433
W/1	Yekaterinburg	56°44.8′N 60°31.6′E / 56.7467°N 60.5267°E / 56.7467; 60.5267	15895,1	15000
X/2	Kurgan	55°22.2′N 65°22.6′E / 55.3700°N 65.3767°E / 55.3700; 65.3767	30939,5	30000

• LORAN, the Western counterpart of Chayka
• Alpha, the Russian counterpart of the Omega Navigation System, still in use as of November 2017.
• OMEGA, the Western counterpart of the Alpha Navigation System, no longer in use.
• Russian 460 metre radio mast