The Implementation of Rapid Acquisition Algorithm for GPS Weak Signal by Using FPGA
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 ab
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The Implementation of Rapid Acquisition Algorithm for GPS Weak Signal by Using FPGA Yuanlei Wang, Yang Gao and Meng Wang
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. Keywords GPS
Weak signal Fast acquisition High orbit
Y. Wang (&) Y. Gao M. Wang Space Star Technology Co., Ltd, Beijing 100094, China e-mail: [email protected]
J. Sun et al. (eds.), China Satellite Navigation Conference (CSNC) 2014 Proceedings: Volume I, Lecture Notes in Electrical Engineering 303, DOI: 10.1007/978-3-642-54737-9_17, Springer-Verlag Berlin Heidelberg 2014
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17.1 Preface Satellites running in high orbit can only receive GPS signal from the other side of the earth. Because of the shield of earth and energy loss through free space field, the visibility and signal intensity of GPS satellites decline very much for user satellites. There may be zero to three visible GPS satellites under this circumstances, even the visible GPS signal can hardly be received [1]. There are several features of high orbit satellites as follow: Weak visibility of GPS satellite: Satellites running in high orbit can receive GPS signal. Because the GPS satellites antenna point to the earth, the GPS receiver fixed on high orbit satellites can only receive the signal from the other side of the earth, resulting the weak visibility of GPS signal. Low signal power: Long distance transmission with atmosphere damping and ionosphere delay give rise to low signal power to be received. Difficulty of signal capture: Low GPS signal power make the capture of visible satellite a troublesome. For this reason, the study of GPS weak signal capture contributes much to the independent positioning of high or
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