The AN/SPY-1 (Array, Navy/Search Protect, Yellow 1) is a US naval radar system manufactured by Lockheed Martin. The array is a passive electronically scanned system and is a key component of the Aegis Combat System. The system is computer controlled, using four complementary antennas to provide 360 degree coverage. The system was first installed in 1973 on the USS Norton Sound and entered active service in 1983 as the SPY-1A on USS Ticonderoga. The -1A was installed on ships up to CG-58, with the -1B upgrade first installed on Princeton in 1986. The upgraded -1B(V) was retrofitted to existing ships from CG-59 up to the last, CG-73.