The Implementation of Rapid Acquisition Algorithm for GPS Weak Signal by Using FPGA

Abstract

The traditional acquisition technology of low orbit GPS signal has been widely applied in the design of GPS navigation receiver. However, navigation receiver can only accept the navigation signal which comes from the other end of the earth when running above the navigation constellation, which results the decline of GPS navigation visibility and signal power, and the navigation signal power from high orbit navigation receiver will reduce 10 dB at least than low orbit navigation receiver and traditional fast acquisition design can not meet design requirements of high orbit navigation receiver. Therefore, this paper present a design which increase times of coherent integration to improve ratio of carrier and noise of received signal, at the same time, it uses full link simulation by simulink to verify feasibility of the design, the final design of weak signal acquisition, through the test of Xilink company Virtex4 series FPGA chip based on the weak signal acquisition sensitivity up to −176 dB. Because the GLONASS navigation system and BDS navigation and GPS navigation system using spread spectrum communication system, different with GPS navigation system in production of presucode ratio and presurange and the carrier frequence parameters. Therefore, this fast acquisition algorithm for GPS weak signal adapt to the design of GLONASS navigation receiver and BDS navigation receiver.