Description of the radar set, tactical-technical characteristics
Figure 1: Antenna of the AN/FPS-3
|pulse repetition time (PRT):|
|pulse repetition frequency (PRF):||400 Hz|
|peak power:||1,5 MW|
|instrumented range:||320 km|
|hits per scan:|
|antenna rotation:||3.3, 5 or 10 rpm|
The AN/FPS-3 was an L-Band air defence radar buildt by Bendix Radio (Div. of Bendix Aviation Corp.). The AN/FPS-3 was the successor of the AN/CPS-5 long-range search radar. The AN/FPS-3 was the beginning of a family of long range search radars. The first units came off the Bendix production line and were ready for installation in late 1950. Forty-eight of these L-band units were used within the first permanent network.
The FPS-3 was a dual beam radar that used a pair of 5J26 Magnetrons with 750 kW peak power. The two transmitter cubicles, the dual modulator and the common high voltage supply were mounted on the antenna framework. Its cabinets hang beneath the antenna, and rotate along with it. Slip rings fed power and control up and 30 MHz IF from the AM-4232 pre-amplifier down to the main console near the operations room. The AN/MPS-7 was a mobile version of the AN/FPS-3.
As the “Cold War” intensified, it was necessary to provide improved technology for the Air Force Defense System. This upgrade was called the Semiautomatic Ground Environment (SAGE) equipment. At the heart of the SAGE system were large-scale digital computers that would process the information from the radar sets and provide intercept control for the USAF. Although the AN/FPS-3 was an excellent radar set for manual operations, it required significant modifications to be compatible with the SAGE system.
This compatibility was achieved by the installation of a Bendix-designed modification kit (AN/GPA-27) which replaced some 90 percent of the components of the original AN/FPS-3 radar to create the new AN/FPS-20 radar set and, which increased the search altitude to 65,000 feet. Installation of these modifications began in 1957.