''Odd Pair'' is NATO codename for Soviet height-finding radar (altimeter) PRV-13 ''The Reliability'', which was constructed in 1978 as the best altimeter in the class. It has successfull long time service history as part of various SAM systems, associated with SA-2, SA-3, SA-5 systems, also as being part of early warning systems in Anti-Aircraft Defence units and Air Force. PRV-13 work along with different types of surveillance radars, like P-37 (Bar Lock), P-18 (Spoon Rest), P-14 (Tall King), etc, that bring full 3D coordinate of a target. The main principle of PRV-X + P-X complex is next: P-X surveillance radar detect azimuth and distance up to a target, these are 2D coordinates. PRV-X altimeter receive the initial 2D coordinates coming from P-X radar, and starting seek for the target using pre-coming data of azimuthal angle and distance, next PRV-X detect height of the target, getting 3rd coordinate. The PRV-13 has max range 310km and able detect target height 100-25000m

Animation tip: Unlike all other types of radar, altimeter dish isn't rotating, but rocking. It has amplitude 0,5-30 deg. with frequency up to 32 waves per minute. The model is real-world scaled and hierarchically linked. All objects and materials have correspondent names.