Fast algorithm of motion state detection based on tri geo-satellites

Aiming at the difficulty to detect the motion state of targets in the satellite-borne passive location system, a fast motion state detection algorithm, based on the principle that the location result of the dual-satellites geolocation using differential time offset (DTO) and differential frequency offset (DFO) should be consistent with that of the tri-satellites geolocation using dual DTOs under the stationary hypothesis, was proposed. Firstly the region of target was obtained by location error analysis. Then the DFO range of this region under the stationary hypothesis was obtained through the statistics. Finally the observed value of DFO at the location time was compared with the DFO range to detect the motion state of target. And the expression of theoretical detection probability was given. The algorithm was verified by the simulation and experiment results. For the targets with velocity above 40 m/s, the detection probabilities are more than 99% when the estimation precision of DTO/DFO is 10 μs/100 mHz. It is demonstrated by the practical data that the proposed algorithm helps the system improve the ability to detect motion state significantly.