Abstract:

The estimation accuracy of time difference of arrival (TDOA) and frequency difference of arrival (FDOA) is crucial to the passive location system using these parameters. In the micro/nano satellite location system, the estimation performance of these parameters will be deteriorated by the cumulative time increasing. In order to solve the problem, the expansion effect of relative frequency companding (RFC) on the complex ambiguity function (CAF) in FDOA direction is analyzed, then the impact of uncompensated RFC on the FDOA estimation accuracy is derived, and then the degradation factor of FDOA estimation accuracy and optimum cumulative time is presented. On the basis of the theoretical analysis, a method of TDOA/FDOA estimation based on time 〖JP2〗varying compensation is also proposed, which can overcome the time and frequency expansion effect caused by timevarying characteristics. Simulation results show that the proposed method can eliminate the estimation accuracy loss effectively, and the parameter estimation accuracy can approach the nontimevarying theoretical limit.