AN/FPS-23
The Motorola AN/FPS-23 was a short-range search radar deployed to the Distant Early Warning Line (DEW Line) "Intermediate" sites as gap-fillers between the long-range AN/FPS-19 Main and Auxiliary stations.
The AN/FPS-23 DEW-Line radar system was manufactured by Motorola, and operated at frequencies between 475 and 525 MHz, with 1 kilowatt of output power. AN/FPS-23 radars were continuous wave (CW) systems composed of geographically-separated AN/FPT-4 Fluttar Transmitters and AN/FPR-2 Fluttar Receivers. AN/FPT-4 Fluttar Transmitters were located only at Intermediate ("I") Sites, while AN/FPR-2 Fluttar Receivers were located only at Main and Auxiliary Sites. The transmitters and receivers were typically about fifty miles apart. The function of this Doppler-effect detection system was to fill the low-altitude gaps between AN/FPS-19 radars located at Main and Auxiliary DEW-Line Sites.
It was declared obsolete in 1963, and the Intermediate stations were closed.
References
This article incorporates public domain material from the Air Force Historical Research Agency website http://www.afhra.af.mil/.