The Research On Weak Signal Acquisition And Tracking Techniques Of Binary Offset Carrier Moduation

Binary Offset Carrier modulation,as a novel modulation,was been picked in 2001 by BETZ, developing very rapidly because of its superiority compared to traditional BPSK modulation techniques. Every one of the third generation of GPS, Galileo and second-generation Compass systems will surely use BOC modulation techniques. As GPS modernization program plans, the GPS III satellite that broadcasts civil L1 C signal is scheduling to be officially launched and put into use in 2014, when the BOC modulation will be firstly put on the civilian table of GPS after its completion of design. L1 C band will broadcast the message signal and the pilot signal, the second generation of China’s Beidou system B1 band is also about using BOC modulation and pilot signal. With the pilot signal,reception of weak signals will gain great help, since the coherent integration time will not be limited by the switching of message bits any more, making a breakthrough on the application of GNSS in weak signal environments. This article is to research the BOC modulated weak signal acquisition and tracking techniques relating to the above background, as follows:BOC signal analysis for its numerical and application characteristics; BOC signal model constructing for simulation experiments; verifying the correctness of signal model with the simulation results; while the BOC signal PRN code correlation function studying.Designing of a new BOC(kn, n) signal tracking method to ensure precise tracking of the signal by preventing the code loop locking on the sub-peak; raising up a correlation function of the structure without secondary peaks; designing for phase tracking loop method and the phase discriminator of this method; and simulation of the above.Key consideration for the pilot signals, then focus on the impact of pilot signals to the traditional method of performance through simulation experiments; the BOC modulated weak signal reception technology analysis and comparison; identifying the most suitable weak signal acquisition methods for new signals.Studying Kalman filtering technique to making sure of its using environment and limits; to design a new Kalman filter-based weak signal acquisition algorithm; to establish the appropriate filter equations, combining with coherent integration design to ensure a-55 db snr-ratio acquisition; simulation of the algorithm.