the S-125M1 (1978) system uses the 5V27D missile. In the early 1980s, each system used one or two radar simulators to survive antiradar missiles. Radars The launchers are accompanied by a command building or truck and three primary radar systems: P-15 radar (NATO codename "Flat Face") or P-15M(2) (NATO codename "Squat Eye") 380 kW C-band target acquisition radar (also used by the 2K12 Kub and 9K33 Osa, range 250 km/155 miles) SNR-125 (NATO codename "Low Blow") 250 kW I/D-band tracking, fire control and guidance radar (range 40 km/25 miles, second mode 80 km/50 miles) PRV-11 (NATO codename "Side Net") E-band height finder (also used by S-75, 2K11 Krug and S-200, range 28 km/17 miles, max height 32 km/105,000 ft) The P-15 is mounted on a van (P-15M(2) on a taller mast for better performance against low-altitude targets) and also an IFF [Identifies Friend or Foe]), SNR-125 on a trailer and PRV-11 on a box-bodied trailer. Variants and upgrades Naval version Work on a naval version M-1 Volna (SA-N-1) started in 1956, along with work on a land version. It was first mounted on a rebuilt Kotlin class destroyer (Project 56K) Bravyi and tested in 1962. In the same year, the system was accepted. The basic missile was a V-600 (or 4K90) (range: from 4 to 15 km, altitude: from 0.1 to 10 km). Fire control and guidance is carried out by 4R90 Yatagan radar, with five parabolic antennas on a common head. Only one target can be engaged at a time (or two, for ships fitted with two Volna systems). In case of emergency, Volna could be also used against naval targets, due to short response time. The first launcher type was the two-missile ZIF-101, with a magazine for 16 missiles. In 1963 an improved two-missile launcher, ZIF-102, with a magazine for 32 missiles, was introduced to new ship classes. In 1967 Volna systems were upgraded to Volna-M (SA-N-1B) with V-601 (4K91) missiles (range: 4–22 km, altitude: 0.1–14 km). In 1974 - 1976 some systems were modernized to Volna-P standard, with an additional TV target tracking channel and better resistance to jamming. Later, improved V-601M missiles were introduced, with lower minimal attack altitude against aerial targets (system Volna-N). Some Indian frigates also carry the M-1 Volna system. Modern upgrades Since Russia replaced all of its S-125 sites with S-300 systems, they decided to upgrade the S-125 systems being removed from