OVERVIEW: Satellite SIGINT systems operating at approximately 40,000 km altitude provide global coverage for intercepting and analyzing electronic emissions, supporting strategic intelligence and early warning missions. These systems utilize high-altitude geostationary orbits to monitor wide areas continuously.

GENERAL DESCRIPTION: In use since the late 20th century, high-altitude SIGINT satellites are equipped with sensitive receivers and advanced signal processing to detect, classify, and geolocate radio frequency emissions across broad frequency ranges. Positioned in geostationary orbit (~35,786 km), they maintain constant coverage over fixed regions, enabling persistent electronic surveillance and communications intelligence (COMINT/ELINT).

ROLE SUMMARY:
Category: Signals Intelligence (SIGINT) / Spaceborne ISR
Primary Use: Wide-area, persistent RF interception and emitter geolocation
Function: Passive detection and analysis of electronic emissions
Platform: Geostationary orbit satellites

See Specific information under [Sensors/EW] section.

SOURCE:
Open-source defense intelligence publications
Federation of American Scientists (FAS)