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CARSR Long range radar Set - A set of long range radar set components built by Raytheon to upgrade FAA legacy radar sets to a common set of transmitters and receivers. Only the antenna components were retained, the rotary joint, diplexer/Polarizer and the physical antenna and drive mechanism.


The Common Air Route Surveillance Radar (CARSR) is a new long-range L-band radar with a range of 200 nm. CARSR is the result of a Service Life Extension Program (SLEP) that replaced the vintage ARSR-1, ARSR-2, FPS-20A, FPS-66A, FPS-67A/B and FPS-93A components with modern components. The klystron transmitters were replaced with a common solid-state transmitter. Even though the receiver and signal processors were upgraded by Northrop Grumman in the early 1990s, they were replaced with more modern software driven components.

The new transmitter components transmit a fan beam as the antenna rotates at five rpm. The SLEP design uses advanced MTD (Moving Target Detector) techniques with enhanced sensitivity and detectability of weak targets in the presence of clutter to replace legacy moving target processing. The CARSR Radar is interfaced with either a Mode S or an ATCBI-6 secondary surveillance radar (Beacon) and also reports weather in NWS six-level format. The CARSR SLEP upgrade also replaces the legacy Common Digitizer-2 (CD-2) processors and associated radar data interfaces.

The CARSR program is now complete and there are 80 operational CARSRs installed across the U.S. and Puerto Rico. In addition, three non-operational CARSRs are located at the FAA’s Aeronautical Support Center in Oklahoma City. The expected life of the upgraded radars is between 15-20 years.

Element Value Notes
Nomenclature CARSR
Origins FPS-20/ARSR-1
Manufacturer Raytheon
Type Long Range Search
Number Made 83
IEEE Band L Band
Frequency 1.2-1.4 GHz
PRF 3 Staggered PRFs
with distinct stagger ratios
Pulse Width 2 Long ~117 us
2 Short ~20 us
within 290 us TX time
4 pulses in each PRI
Rotation Speed 5 rpm
Power 8 amplifier modules
output a minimum
50 kW peak power
Range 200 nmi Long
Altitude 100,000 ft
CARSR Radar Configurations
Number Configuration Antenna Owner/Operator Notes
2 CARSR (FPS-20A) 1561 L-Band DOD/DHS/FAA
5 CARSR (FPS-66A) 1561 L-Band DOD/DHS/FAA
15 CARSR (FPS-67/A/B) 1561 L-Band DOD/DHS/FAA
1 CARSR (FPS-93A) 1561 L-Band DOD/DHS/FAA
28 CARSR (ARSR-1) 7172 L-Band DOD/DHS/FAA
15 CARSR (ARSR-2) 7172 L-Band DOD/DHS/FAA
1 CARSR (ARSR-2) 1561 L-Band DOD/DHS/FAA
13 CARSR (ARSR-3) 9200S L-Band DOD/DHS/FAA

See Also:


  • Wang, Brookner, Cornell Gerecke and Farr, Modernization of Enroute Air Surveillance Radar, IEEE Transactions on Aerospace and Electronic Systems, Vol. 48, No. 1, January 2012, pages 103-115.


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