Vandenberg AFB Radar Site

 (1960s-Active) - A US Air Force (USAF) Long-Range Radar (LRR) site first established in the 1960s near Lompoc, Santa Barbara County, California. The site is used to identify and track military and civilian aircraft movements within a 200-mile radius and to provide air-ground radio communication with those aircraft. Replaced coverage provided by Lompoc Air Force Station that closed in 1968. Lompoc AFS was located just 6 miles from this site. Initially operated in support of the Western Space And Missile Center (WSMC) at Vandenberg AFB, later assigned a JSS ID of J-35, and an FAA ID of VBG. Active USAF Radar Site.

History
Note: The text below was adapted from the Western Space And Missile Center (WSMC) Western Test Range: Landbased Instrumentation Handbook because it gives a good description of the physical and equipment configuration of the Vandenberg radar site as of 1 Jul 1981. It also describes the system configuration that the radar site supported as well as naming the other six radar sites that also participated. At the time the handbook was written the SAGE System was being dismantled, USAF radar sites were being closed and replaced with FAA radar sites and some of the radar sites mentioned in the handbook were already closed when it was written.

The Surveillance Radar systems provided the traffic status of the sea and air spaces adjacent to WSMC. The major equipment was installed in Building 500 on South Vandenberg AFB. Included was the equipment for the microwave system interfaces linking Vandenberg AFB with the rest of WSMC and the Pacific Missile Test Center (PMTC) at Point Mugu and San Nicolas Island. By 1981 the two major surveillance systems were the ARSR-1D primary radar and the UPX-23 Radar Recognition (IFF) secondary radar system. The output of the two radar systems was digitized by an FYQ-49 Common Digitizer.

The radar site was located along Honda Ridge approximately 2 miles from the Pacific Ocean, at an altitude of approximately 1500 feet, overlooking Vandenberg AFB and the surrounding area. The structures at the site include a radar antenna tower, two 15-foot towers each supporting a microwave parabolic reflector, one 140-foot tower for a microwave reflector, television system trailers, the main equipment building, and an auxiliary power generator building. UHF/VHF radio receivers, transmitters, and associated antennas were also located at this site. Data from the surveillance systems were transmitted to the Area Control Center (ACC) for display.

Primary Radar System
The ARSR-1D Radar was developed and manufactured to meet requirements specified by the Federal Aviation Agency (FAA) and was the predominate radar in the FAA's en-route Air Traffic Control System. The radar was a pulse type set operating in 1280 to 1350 MHz frequencies and produces a map-like display of the locations of aircraft within a 200-nmi radius of the radar's antenna. The display is presented on PPI at the master console located at the surveillance site, and at remote PPI indicators at other locations, such as the Area Control Center, Bldg. 7000A, North Vandenberg AFB and the PMTC at Point Mugu.

Secondary Radar System
The Radar Recognition (IFF) System is an auxiliary to the primary ARSR-1D radar. The IFF System provides ground observers with methods of identifying a particular radar target. The operation of the system depends upon the transmission of a coded interrogation signal and the receipt of a reply from a transponder carried in the aircraft. Two types of coding are available: coding of interrogation and the coding of replies. Operators have the choice of transmitting any of the three interrogation codes. More than 50 reply codes are available but the selection of reply coding is the responsibility of the aircraft.

The Vandenberg AFB IFF System consisted of one UPX-6 Radar Recognition set as a basic transmitter-receiver, an antenna, and several UPA-24A Decoder Group Assemblies (one for each PPI scope on which IFF is to be displayed). This equipment together made up the UPX-23 system.

Common Digitizer (CD)
A FYQ-49 Common Digitizer extracted aircraft returns from radar video and transmitted them to a remote control center over 4-wire voice quality communication lines. The CD provided both primary (ARSR-1D video) and secondary (IFF video) video processing.

Area Control Center Display System (ACCOS)
The system physical configuration consisted of four equipment cabinets located in Building 7000, Room 210 and three (3) Air Controller Display Position consoles located in Building 7000, Area Control Center.

Digitized radar information was fed from seven radar sites located at

Radar track information was transmitted remotely from the FYQ-47 (or FYQ-49) common digitizer modems located at each radar site in a serial format at 2400 baud. The Modem Interface Unit (MIU) converted the serial data stream to a 16-bit parallel field which is then read by the Central Processor (CP). The CP assembles the received data fields into a complete target report which typically contains the Label Field, Range Field, Azimuth Field and Mode C Field (altitude).

The data available to the ACCOS is contained in a message made up of either five or seven fields of thirteen bits each, containing some or all of the following information:


 * Range
 * Azimuth
 * SSR Code
 * Altitude
 * Digitizer and Radar Status

The receive modems or data sets (Model 201B) were located in the ACC area of Vandenberg AFB. There were (3) modems per each digitizer for a system total of (21) modem pairs for the (7) radar sites. The digital output of the modems was routed through an interconnection panel and into the ACCDS.

Common Digitizer 2 (CD-2)
By the early 1990s, the ARSR-1D search radar was upgraded to an ARSR-1E and remained in operation until it was replaced by an ARSR-4 radar between 1996 and 1999. Before the ARSR-4 was installed the Common Digitizer CD-2 would have replaced the FYQ-49 as the radar digitizer. The ARSR-4 radar had the digitizer functionality built into that set so the CD-2 was no longer required after it was commissioned.

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Current Status
Active USAF facility near Lompoc in Santa Barbara County, California.

{| See Also:
 * Los Angeles ARTCC
 * JSS System
 * FAA Air Route Traffic Control Centers
 * US Radar Sets

Sources:

Links:
 * Radomes - Vandenberg AFB Radar Site
 * Wikipedia - Joint Surveillance System