Air Route Surveillance Radar

The Air Route Surveillance Radar is used by the United States Air Force and the Federal Aviation Administration to control airspace within and around the borders of the United States.

The ARSR-4 is the FAA's most recent (late 80s, early 90s) addition to the "Long Range" series of radars, which are search radars with a range of at least 200 nmi. The Westinghouse system is solid state and has a 250 nmi range. In addition, the ARSR-4 features a "look down" capability that enables the radar to detect aircraft attempting to elude detection by flying at low altitudes, advanced clutter reduction via hardware and software post-processing, and enhanced poor-weather detection of aircraft. A Beacon system, the ATCBI-6M (a monopulse system), is installed along with each ARSR-4. However, since the ARSR-4 is a 3D radar, it is capable of determining aircraft altitude independently of its associated Beacon (albeit less accurately).

ARSR-4 systems are installed along the borders and coastal areas of the CONUS, Guantanamo Bay Naval Base in Cuba, the municipality of Yigo on Guam, and a training site at the FAA's Mike Monroney Aeronautical Center in Oklahoma City. They are generally unmanned, being equipped with remote monitoring of both the radar data and the status of the radar's health and environment.

History
The Raytheon-built ARSR-1 was introduced in 1958 had maximum range of 200 mi. The ARSR-2 was developed in the 60s as a replacement for the ARSR-1, also operating in the L-band with a 200 mile range. From a users perspective the ARSR-1 and ARSR-2 function nearly identically. Components which had proved troublesome in the ARSR-1 were redesigned in order to improve the reliability of the ARSR-2. Existing ARSR-1 systems were then retrofitted with the more reliable ARSR-2 components. As of June 2012, approximately 60 ARSR 1/2 RADARS are still operating in the United States. Thirteen ARSR-1/2 systems have been replaced With modern Common ARSR systems. Despite their age, ARSR 1/2 RADARS are still maintained at high rates of reliability by FAA technicians. Giant electron tubes like the one Vice President Gore used in a televised interview to symbolize the need for FAA modernization are still in use nationwide.

All ARSR-1/2s are slated to be replaced by the Common ARSR by the end of 2015. Common ARSR is abbreviated as CARSR. The CARSR shares transmitter components and software with the FAA's newest airport surveillance radar the ASR-11. Like the ASR-11, the CARSR is a completely solid state RADAR.

The Westinghouse-built ARSR-3 and 3D search radar was used by the FAA in the Joint Surveillance System (JSS). The radar operated in the L-band at 1250 to 1350 MHz and detected targets at a distance beyond 240 mi. The D model had height-finder capability.

The Westinghouse-(now Northrop-Grumman)-ARSR-4 built 3-D air surveillance radar in the 1990s for the JSS system. By the late 1990s, this radar had replaced most of the 1960s-vintage AN/FPS-20 variant search radars and a number of ARSR-3 search radars under a project termed the "FAA/Air Force Radar Replacement" (FARR) program.