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.

[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.

The radar uses two antenna to determine target altitude by the V-beam system with azimuth scanned mechanically.

[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.