The AN/FPS-20 was a widely used L bandearly warning and ground-controlled interception radar system employed by the United States Air ForceAir Defense Command, the NORADPinetree Line in Canada, the USAF CONAD in the continental United States, and a variety of other users. The design started life as the BendixAN/FPS-3 in 1950, was upgraded to the FPS-20, then spawned over a dozen different variants as additional upgrades were applied. The FPS-20 formed the backbone of the US air defense network through the early Cold War with over 200 units deployed. Most FPS-20 sites were replaced by modern equipment in the late 1960s, although a number were turned over to the FAA, modified for air traffic control use, and became ARSR-60s.
The first AN/FPS-3 arrived in December 1950, slated for installation at Eniwetok Atoll to control aircraft involved in the atomic bomb tests of early 1951.[1] Over the next few years, 48 FPS-3s were installed to replace older systems in the Lashup Radar Network. The FPS-3 and was also produced as the AN/MPS-7, a mobile version.[2][a] The system used two 5J26 magnetrons at 750 kW peak power, operating at 1300 MHz a 400 Hz pulse repetition frequency (prf) and 2 microsecond pulse width.[4] The antenna was driven at three fixed speeds of 3.3, 5 or 10 RPM, normally operating at 5. Many of the operating modules were mounted on the rotating platform, with the output signals fed via slip rings to amplifiers and displays at the base of the unit.
The FPS-3 was limited to about 55,000 feet (17 km) altitude, which was seen as a limitation in light of new jet-powered bombers known to be in development in the USSR. This led to the development of the AN/GPA-27 add-on unit, increasing the altitude to 65,000 feet (20 km).[N 1] Installations began in 1956.[2][N 2] New-build units from Bendix with this equipment pre-installed became the AN/FPS-20 in 1957.[N 3] Otherwise similar units with an antenna from General Electric were known as the AN/FPS-20B. The slotted-waveguide antenna pictured above the AN/FPS-20 is for the associated IFF system.[5]
The FPS-20s were simple pulse-radar systems and subject to jamming using basic techniques. This led to a second series of upgrades to provide anti-jamming capabilities starting in 1959. Among these were the GPA-102 (MK-448) which turned an FPS-20 into an FPS-64 and a FPS-20A to an FPS-66, and the GPA-103 (MK-447) which turned a FPS-20 into an FPS-65 and the FPS-20A into an FPS-67.[6] Similar upgrades using a Canadian OA-4831 system produced the AN/FPS-87 and AN/FPS-87A. The BADGE 412-L upgrade of the FPS-20A created the AN/FPS-82.
A more major update was the MK-747, which added a new antenna from Raytheon, the Diplex Gating Unit (DGU), a bandpass filter and other modifications, to produce the AN/FPS-91 and 91A. The similar MK-748 applied to the -60 series resulted in the AN/FPS-64A, -65A, -66A and -67A. Canadian AN/FPS-87s were also converted, becoming AN/FPS-93 and 93A. These units were used with the SAGE system.[7]
The FPS-20 was widely used in Japan. They produced their own series of modifications, including a tunnel diode based amplifier and a separate receiver for the Airborne Instruments Laboratories system, producing the AN/FPS-20/20A JAPAN, or -J.
The Indian Air Force used the FPS-20 with a new digital moving target indicator (MTI) system from Bendix to create the AN/FPS-100 and 100A. These systems were known as the "Blue Pearl", or Bendix Radar Processor BRP-150. These were remanufactured units with a new antenna, and included a new low-noise front-end amplifier. General Dynamics later produced a similar digital MTI system, the AN/FPS-113.
^The GPA-27 may be the slotted waveguide mounted on the top of the main antenna seen in images of the FPS-20. However, some images show this on radars labeled FPS-3, although this may be before they were renamed.
^Winkler refers to upgraded units as FPS-3B on page 76, but other sources agree with his own page 33 that these were actually called FPS-3A.
^Winkler does not mention this directly, but notes on page 77 that -3A units were also renamed FPS-20 when receiving updates.
^According to Winkler, the FPS-3 design was developed from the earlier CPS-5[3] design by Bell Labs and General Electric. radomes.org disputes the link with the CPS-5, which had a somewhat different antenna as can be seen in the photographs in Winkler's work. This confusion may be due to the language in Bacque, which refers to "newly developed AN/FPS-3 long-range radar set".
Bacque, Cramer (October 1990). . Archived from the original on 1999-10-02.
Winkler, David F. (June 1997). Searching the skies: the legacy of the United States Cold War defense radar program(PDF). Headquarters Air Combat Command.
Further reading
, radomes.org
AN/FPS-20, 20A, 20B, radomes.org
AN/FPS-3 Modification History Tree, radomes.org
AN/FPS-20 @ fas.org
October 21, 2023
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The AN FPS 20 was a widely used L band early warning and ground controlled interception radar system employed by the United States Air Force Air Defense Command the NORAD Pinetree Line in Canada the USAF CONAD in the continental United States and a variety of other users The design started life as the Bendix AN FPS 3 in 1950 was upgraded to the FPS 20 then spawned over a dozen different variants as additional upgrades were applied The FPS 20 formed the backbone of the US air defense network through the early Cold War with over 200 units deployed Most FPS 20 sites were replaced by modern equipment in the late 1960s although a number were turned over to the FAA modified for air traffic control use and became ARSR 60s AN FPS 3 AN FPS 20Bendix AN FPS 20 radarCountry of originUnited StatesTypeGeneral Surveillance RadarFrequencyL bandPRF440Pulsewidth4 mSRPM3 3 5 10 RPMPower750 kW x 2Other NamesAN FPS 3 AN MPS 7 AN FPS 64 AN FPS 65 AN FPS 66 AN FPS 67 AN FPS 91 AN FPS 93 AN FPS 100 AN FPS 113 AN GPS 4 AN FPS 508The FPS 3 The first AN FPS 3 arrived in December 1950 slated for installation at Eniwetok Atoll to control aircraft involved in the atomic bomb tests of early 1951 1 Over the next few years 48 FPS 3s were installed to replace older systems in the Lashup Radar Network The FPS 3 and was also produced as the AN MPS 7 a mobile version 2 a The system used two 5J26 magnetrons at 750 kW peak power operating at 1300 MHz a 400 Hz pulse repetition frequency prf and 2 microsecond pulse width 4 The antenna was driven at three fixed speeds of 3 3 5 or 10 RPM normally operating at 5 Many of the operating modules were mounted on the rotating platform with the output signals fed via slip rings to amplifiers and displays at the base of the unit The FPS 3 was limited to about 55 000 feet 17 km altitude which was seen as a limitation in light of new jet powered bombers known to be in development in the USSR This led to the development of the AN GPA 27 add on unit increasing the altitude to 65 000 feet 20 km N 1 Installations began in 1956 2 N 2 New build units from Bendix with this equipment pre installed became the AN FPS 20 in 1957 N 3 Otherwise similar units with an antenna from General Electric were known as the AN FPS 20B The slotted waveguide antenna pictured above the AN FPS 20 is for the associated IFF system 5 The FPS 20s were simple pulse radar systems and subject to jamming using basic techniques This led to a second series of upgrades to provide anti jamming capabilities starting in 1959 Among these were the GPA 102 MK 448 which turned an FPS 20 into an FPS 64 and a FPS 20A to an FPS 66 and the GPA 103 MK 447 which turned a FPS 20 into an FPS 65 and the FPS 20A into an FPS 67 6 Similar upgrades using a Canadian OA 4831 system produced the AN FPS 87 and AN FPS 87A The BADGE 412 L upgrade of the FPS 20A created the AN FPS 82 A more major update was the MK 747 which added a new antenna from Raytheon the Diplex Gating Unit DGU a bandpass filter and other modifications to produce the AN FPS 91 and 91A The similar MK 748 applied to the 60 series resulted in the AN FPS 64A 65A 66A and 67A Canadian AN FPS 87s were also converted becoming AN FPS 93 and 93A These units were used with the SAGE system 7 The FPS 20 was widely used in Japan They produced their own series of modifications including a tunnel diode based amplifier and a separate receiver for the Airborne Instruments Laboratories system producing the AN FPS 20 20A JAPAN or J The Indian Air Force used the FPS 20 with a new digital moving target indicator MTI system from Bendix to create the AN FPS 100 and 100A These systems were known as the Blue Pearl or Bendix Radar Processor BRP 150 These were remanufactured units with a new antenna and included a new low noise front end amplifier General Dynamics later produced a similar digital MTI system the AN FPS 113 Contents 1 Notes 2 References 2 1 Citations 2 2 BibliographyNotes Edit The GPA 27 may be the slotted waveguide mounted on the top of the main antenna seen in images of the FPS 20 However some images show this on radars labeled FPS 3 although this may be before they were renamed Winkler refers to upgraded units as FPS 3B on page 76 but other sources agree with his own page 33 that these were actually called FPS 3A Winkler does not mention this directly but notes on page 77 that 3A units were also renamed FPS 20 when receiving updates According to Winkler the FPS 3 design was developed from the earlier CPS 5 3 design by Bell Labs and General Electric radomes org disputes the link with the CPS 5 which had a somewhat different antenna as can be seen in the photographs in Winkler s work This confusion may be due to the language in Bacque which refers to newly developed AN FPS 3 long range radar set References EditCitations Edit Bacque 1990 a b Winkler 1997 p 76 CPS 5 at FortWiki com Radar Types A high resolution Slotted waveguide IFF antenna for the AN FPS 3 radar by J Y Wong 1957 NRC Canada Winkler 1997 p 40 Winkler 1997 pp 77 78 Bibliography Edit Bacque Cramer October 1990 History of the BFEC Archived from the original on 1999 10 02 Winkler David F June 1997 Searching the skies the legacy of the United States Cold War defense radar program PDF Headquarters Air Combat Command Further readingAN FPS 3 3A 3B MPS 7 radomes org AN FPS 20 20A 20B radomes org AN FPS 3 Modification History Tree radomes org AN FPS 20 fas org Retrieved from https en wikipedia org w index php title Bendix AN FPS 20 amp oldid 1088105741, wikipedia, wiki, book, books, library,
