Abstract: The present invention is directed toward a navigation system and method for a high orbit spacecraft, which passively utilizes UHF signals carrying intersatellite ranging data transmitted by a constellation of satellites that travel in lower orbits around a celestial sphere. The navigation system enables the high orbit spacecraft to self locate its position relative to an earth centered coordinate frame and comprises a receiver for receiving the UHF signal, carrying the intersatellite ranging data and a Kalman or optimum filter coupled to the receiver for processing the ranging data received by the receiver and generating and updating spacecraft position data.

Abstract: The present invention is directed toward a navigation system and method for a high orbit spacecraft, which passively utilizes UHF signals carrying intersatellite ranging data transmitted by a constellation of satellites that travel in lower orbits around a celestial sphere. The navigation system enables the high orbit spacecraft to self locate its position relative to an earth centered coordinate frame and comprises a receiver for receiving the UHF signals carrying the intersatellite ranging data and a Kalman or optimum filter coupled to the receiver for processing the ranging data received by the receiver and generating and updating spacecraft position data.

Abstract: A system of making satellite-to-ground range measurements, carrying out communications between a ground station and a constellation of autonavigating satellites, and using these range measurements to improve navigation accuracy is disclosed. The system comprises an anchor that is in a fixed position relative to the earth. The anchor implements a filtering algorithm to arrive at solutions for the satellites' positions based on measured satellite positions and predicted satellite positions. Each time a new measurement is received by the anchor an update is generated. In this manner the system is capable of updating satellite positions at a greater rate than similar prior art systems, thereby, decreasing the transient response associated with satellite delta-v maneuvers and decreasing the quantity of data that must be exchanged by the anchor and the satellites.