Approximate Position Estimation Method of Weak-Signal Receiver of Global Navigation Satellite Systems Assisted by Barometric Altimeter

Abstract

The satellite navigation receiver works in an environment, where the received signal is very weak. Sometimes, frame synchronization is impossible, for the antenna rotates with the flight carrier, and occlusions exist in the environment. After losing look, it is necessary to positioning reacquired signals. Rapid positioning can be completed without frame synchronization, utilizing auxiliary positioning algorithms like A-GPS. If the carrier is highly dynamic, however, the computing load of reacquired signal positioning would be too high, owing to the extreme fuzziness of the approximate position. Therefore, the application of auxiliary positioning algorithms is premised on the acquisition of the approximate position information, when frame synchronization is not possible. This paper proposes a method for estimating the approximate position of a satellite navigation receiver without frame synchronization: The approximate position is quickly obtained by measuring the elevation with a barometer, and searching under a user-defined “geocenter-satellite” coordinate system. Simulation results show that, the proposed algorithm could successfully compute the approximate position, when the barometric altimeter measures elevation with an accuracy within 1.8km, and when the coordinate system is established based on satellites with a long distance and a low angle of elevation, under the condition of global navigation satellite system (GNSS) constellation.