The Naval Ocean Surveillance System (NOSS) is a series of signals-intelligence satellites that have conducted electronic signals intelligence for the U.S. Navy since the early 1970s.[1] The first series of satellites were codenamed "White Cloud" or "PARCAE", while second- and third-generation satellites have used the codenames "Ranger" and "Intruder".
The system is operated by the United States Navy, and its main purpose was tactical geolocation of Soviet Navy assets during the Cold War. NOSS involves satellite clusters operating in low Earth orbit to detect radar and other electronic transmissions from ships at sea and locate them using the time difference of arrival technique.[2]