| As the representative of satellite navigation system, Global Positioning System (GPS) hasbeen studied for several decades. However, China has pays more attention to crucialtechnology of satellite positioning system these year. The Chinese navigation system namedBeidou System is alternative except for GPS, GLONASS and GALILEO. In this paper, a dual-mode satellite positioning receiver combined GPS with BeiDou positioning system is studied.Today, with the mature technology of GPS, it is necessary to develop satellite positioningsystem independently. On the basis of compatible mode, improve the performance ofbaseband processing in the BeiDou receiver can be imporved singularly.Firstly, this paper analyzed the development situation of global satellite positioningsystem, described GPS and BD positioning system and their signal form in detail. It alsointroduces the operating principle of the receiver, the spread spectrum capture algorithm of thereceiving baseband processing, and its signal tracking design methodology. On signalcapturing, the combined method of the time-domain based captureing and the frequency-domain based on FFT is discrpted. According to the property of GPS navigation data bit insignal,180°-flipping may appear in the period of20ms. Combing the original capture method,this paper proposed a novel method based on the dichotomy to capture the satellite signal,improve sensitivity at the same time to accelerate the speed of the algorithm. The performanceof the proposed method has been proven by matlab simulation. Duing to BD signals exist NHcoding, the difficulty is far higher than the GPS of weak signal detection in addition tochecking the navigation bit flip location.In the following, it analyzed the operating principle of tracking calculation method,including code tracking loop, carrier tracking loop, loop fliter and data adjustment. Becausethe receiver often works in low SNR environment, this paper designs a new tracking resolutionwith noncoherent of DLL, four quadrant arctangent of FLL and Costas PLL. The looptracking performance under low SNR will be improved. After comprehensive analysis of the synchronous principle of GPS and BD, the simulation of tracking calculation methodis realizedin MATLAB.The whole receiver performance is provedto satisfy the system requirements. The solutionproposed in this paper could been used to design of real-time receiver system directly, and laysfoundations to the high sensitivity GPS\BD dual mode receiver. |
