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 that were comprised 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.
Ed Note: In the text below, it is stated that the FPS-23 operates at 408MHz. We believe this to be a "typo", and should read 480MHz.