An analysis of the USA-202 ORION satellite and its capabilities, based on classified documents.
A radiotelescope in the sky: the USA-202 ORION satellite
Author: rob1blackops
History of the US high-altitude SIGINT system
Following our previous article which described what kind of Soviet emitters the USA could target, here is a timeline of the satellites that performed the collection.
Signal intelligence 101: SIGINT targets
A quick overview of the various types of signal intelligence targets, with an emphasis on the Soviet Cold War systems
SatelliteObservation.net 