Reference emitters are a vital part of ground-based SATCOM geolocation systems. They act as calibrators to correct or compensate for inaccuracies in the geolocation algorithms within each system. Presently there are two types of reference emitters: Reference Signals of Opportunity (RSOs) and Controlled Reference Emitters (CREs). RSOs are SATCOM signals in which the system operator has identified a general location of the emitter. Typically, this location isn't accurate enough to provide high fidelity compensation to the process. RSOs may not be transmitting when needed and are, therefore, the least reliable reference. CRE locations are precisely known and can be manipulated by an operator. Enhanced Reference Emitters (EREs) will provide operators more capable signals to allow for more precise calibrations to the geolocation model. An ERE will correct the largest source of error, which is inaccurate ephemeris. By collecting range and speed data constantly on tasked satellites provides on-demand ephemeris to generate high precision satellite positioning and velocity corrections to predicted orbits. Utilizing spread spectrum technology, the range and velocity data from multiple EREs can be transmitted as part of the signal to the geolocation unit for consolidation. This provides even higher precision positioning resulting in much high-quality geolocation results.
