Satellite Interferometer as an Advanced Navigation/Communication System

Abstract

An orthogonal system of interferometry baselines aboard a geostationary satellite is considered for a variety of applications involving navigation, surveillance, and traffic control. The position determination is based on the relationship between the measured phase differences, the known and unknown transmitter positions and other systematic error model parameters using a generalized Least-Squares estimation procedure. Study of the effects of the various system and error model parameters on the position accuracy reveals that the accuracy is critically dependent on the baseline length and on the magnitude of the random component of the measuring errors. With a 50-m baseline, the obtainable accuracy at a frequency of 1.5 GHz is comparable to that of the NAVSTAR/GPS system. Several trade-offs with respect to the system accuracies, the number of users, data rates, hardware costs, etc., are examined. Simultaneous utilization of the same communication channels for both navigation and data transfer is found feasible. Based principally on the equipment requirements of potential users, five candidate or “strawman” interferometer systems are configured. The overall performance of the interferometer system is considered excellent when compared with other existing or planned navigation systems. Considering the interest and needs of prospective users for a multicapability system, this interferometry system is considered potentially viable in meeting their requirements.