P-15 FLAT FACE B-1S LONG RANGE SURVEILLANCE RADAR (SOVIET UNION)
In 1952 SRI-244 started development of what become the P-15 early warning radar, by 1955 the radar had passed state trials and was accepted into service with the anti-aircraft troops of the Soviet armed forces.. The P-15 was designed to detect aircraft flying at low altitude making use of the C-Band (UHF) and came to be associated with the SA-3 Surface-to-Air Missile (NATO reporting name "GOA") although it was later replaced by the P-15M2 "Squat Eye" radar which mounted a single radar antenna on a 20-30 meter mast to improve coverage.
The P-15 is a high mobility radar and with the antenna mounted directly on a single truck (Zil-157) or trailer, the system was able to be deployed and taken down in no more than 10 minutes. The P-15 uses two open frame elliptical parabolic antenna measuring 11 x 5,5m, accomplishing both transmission and reception, each antenna being fed by a single antenna feed. The radar can rapidly shift its frequency to one of four pre-set frequencies to avoid active interference with passive interference being removed by a coherent Doppler filter. Azimuth was determined by mechanical scanning with an associated accompanying PRV-11 Radar (NATO reporting name "Side Net") used to determine elevation. A secondary radar for IFF (Identification of Friend or Foe), normally the 1L22 "Parol) is generally used in conjunction with the P-15.
The system was continuously improved and modernised, replacing outdated mercury based electronics, the introduction of a more sensitive receiver which improved the detection range and a new amplifier for the transmitter. Further improvements were made in 1970 when a pulse coherent Doppler filter (moving target indicator) was included to remove passive clutter (by up to 50 dB), the first radar to employ this modification in the Soviet Union. By 1974 the modernisation of the P-15 was so extensive that it resulted in a new designation, the P-19, also known as the 1RL134 and known in the west as the Flat Face B. The system has an operating range of 200 to 250km and is capable of simultaneously guiding 3 missiles.
The P-15 was operated by the Soviet Union from 1955 and though it has since become obsolete it was passed down to successor states after the fall of the Soviet Union. Many of these systems were employed in Southern African region and Angola where this particular system was captured by South African Forces in the 1980's.