Ground Equipment Facility J-31 is a Joint Surveillance System radar site of the Western Air Defense Sector (WADS) and the Federal Aviation Administration's air traffic control radar network for the Los Angeles Air Route Traffic Control Center. The facility's Air Route Surveillance Radar Model 1E with an ATCBI-6 beacon interrogator system are operated by the FAA and provide sector data to North American Aerospace Defense Command. The site provided Semi-Automatic Ground Environment data to the 1959-66 Norton AFB Direction Center for the USAF Los Angeles Air Defense Sector. The site also provided Project Nike data to the 1960-74 Fort MacArthur Direction Center ~3 mi (4.8 km) away for the smaller US Army Los Angeles Defense Area—as well as gap-filler radar coverage for the 1963-74 Integrated Fire Control area of Malibu Nike battery LA-78 on San Vicente Mountain.

The Joint Surveillance System (JSS) is a joint United States Air Force and Federal Aviation Administration system for the atmospheric air defense of North America. It replaced the Semi Automatic Ground Environment (SAGE) system in 1983.