DERA transmitter location service (TLS)

Satellite communications systems-civil and military-are subject to interference from ground-based sources. This interference can be caused by ground station equipment faults, human error, and deliberate attempts to disrupt signals. The impact of such interference on satellite operators and users varies from mild annoyance through to loss of revenue and denial of vital communications links. DERA has, for several years, supported TLS from its Defford site, providing a service for commercial and military customers. The service is based on the geolocation technique, whereby the downlinks of two or more transparent transponder satellites are processed to calculate the location of RF sources. This paper presents an overview of geolocation and its principles, and describes the capability of the DERA TLS in meeting the needs of satcom service providers, both now and in the Skynet 5 era. In describing the principles of satellite based geolocation, fundamental constraints on the achievable accuracy of emitter localisation are also considered.