P-20 radar
P-20 in a Romanian museum
Country of origin Soviet Union
No. builtE band/F band
TypeEarly warning ground control.
Range250 km (155 miles)
Altitude18 km (60,000 feet)
Azimuth360 degrees
Precision0.46 km range, 1.5 degree azimuth
Power1 MW

The P-20 "Periskop" (Russian: "Перископ"; English: Periscope), also referred to by the NATO reporting name "Token"[1][2][3] in the west, is a 2D E band/F band[4] radar developed and operated by the former Soviet Union.


The P-20 development was started in 1946 when State Federal Order of the Red Banner Research Institute Number 20 (now called All-Union Scientific Research Institute of Radio Engineering or VNIIRT[5]) was given the task of developing stationary and mobile early warning ground control and interception radar for the Soviet Air Force.[6] The stationary radar later became the P-50 but the mobile radar was to become the P-20. The design inspired a number of successors including the P-30, P-35 and P-37 radar.[7]

The P-20 was the first Russian radar to use the decimetric wavelength, the first prototype being created in 1947, and a factory test unit in 1949.[6] By 1949 the radar had completed state trials and was accepted into wide service within the Soviet airforce, the designers of the P-20 were awarded the State Prize of the USSR in 1950 in recognition of the achievement.[7]


The P-20 is a semi-mobile radar with equipment mounted on eight ZIl-151 trucks,[7] components include the control cabin and power supply equipment as well as a trailer for the antenna and transmitter equipment. The antenna system of the P-20 consists of two open frame truncated parabolic antennae accomplishing both transmission and reception. The radar uses two antenna to determine target altitude by the V-beam system with azimuth scanned mechanically. The upper antenna is tilted to an angle of 45 degrees[6] from horizontal which results in each target appearing twice on the indicator, the distance between the two allows the targets altitude to be approximately estimated by the operator.[6]

The P-20 had four indicators to display the information generated from the radar, panoramic, range and altitude as well as a remote indicator.[7] The radar used five separate channels for reception and transmission, using different frequencies to avoid mutual interference between the beams, three beam channels being used by the upper antenna and two for the lower antenna.[6]


The P-20 was operated by the Soviet Union from 1949 and though the radars have since become obsolete, they were passed down to successor states after the fall of the Soviet Union. The design has been superseded by later designs like the P-37 radar.

See also


  1. ^ Early Warning Radar Stations/Soviet P-3, P-8 and P-20 Radar (PDF) (Report). Central Intelligence Agency (published 11 January 2008). 1957. Retrieved 17 July 2023.
  2. ^ Soviet Technical Manual on the P-20 Radar (Part II) (PDF) (Report). Central Intelligence Agency (published 13 May 2014). 28 July 1960. Retrieved 17 July 2023.
  3. ^ Foreign Radar Recognition Guide (Report). Central Intelligence Agency (published 28 August 2001). 1 September 1959. p. 58. Retrieved 17 July 2023 – via Internet Archive.
  4. ^ Nance W.H (1968). "Quality Elint". Studies in Intelligence. 12 (2 (Spring)): 7–19.
  5. ^ история: 1947-1970 гг. (in Russian). VNIIRT. 15 January 2002. Archived from the original on 20 April 2008. Retrieved 31 January 2009.
  6. ^ a b c d e Первый локатор сантиметровых волн (in Russian). Воздушно-космическая оборона. 2003–2009. Archived from the original on 18 April 2013. Retrieved 31 January 2009.
  7. ^ a b c d "РЛС П-20 "ПЕРИСКОП" (Bar Lock)" (in Russian). pvo.guns.ru. 16 February 2005. Retrieved 31 January 2009.
  8. ^ "Trade Registers". Retrieved 19 December 2014.