Research On Acquisition And Tracking Algorithms For Satellite Navigation Signal Based On BOC Modulation

The binary offset carrier (BOC) modulation has been widely used to the satellite navigation signal to facilitate the coexistence with different navigation systems such as Beidou, Galileo and GPS. It can also improve the tracking accuracy and multipath resistance. However, multiple correlation peaks of the BOC signal cause the ambiguity which must be solved for acquisition and tracking. Additionally, with more Global Navigation Satellite Systems (GNSS) coming into use, it’s desirable for the new-generation GNSS receiver to make full use of the multiple in-service GNSS to enhance its navigation performance. The key technique for a receiver to achieve adaptation among multi-GNSS is the BOC signal acquisition and tracking algorithms. In this paper we focus on developing algorithms to solve the ambiguity problem and improve the scalability of BOC signal acquisition and tracking methods. The main contents are as follows:Since the BPSK-like algorithm treats each sideband of the BOC-modulated signal as a individual signal, and the two sidebands of the AltBOC(10,5) signal in Beidou locating in B2band carry different navigation data, we explore to apply the BPSK-like algorithm to Beidou AltBOC(10,5) signal acquisition in this paper. Besides, it is found that the auto-correlation function (ACF) of MBOC(6,1,1/11) signal is similar to the ACF of BOC(1,1) signal by simulation, so the Autocorrelation Side-Peak Cancellation Technique (ASPeCT) is also taken into use in this paper for MBOC(6,1,1/11) signal. Simulation results show that these two algorithms can be used to realize unambiguous tracking and obtain better tracking accuracy. This is meaningful for the design of multi-GNSS compatible navigation receiver.For the output of ASPeCT algorithm still has two side peaks, a new enhanced ASPeCT algorithm is proposed in this paper. Simulation results show that this algorithm has a better performance of solving the ambiguity problem than the traditional ASPeCT algorithm. Meanwhile, since the ASPeCT algorithm is only suitable for BOCs(n,n) signal, a new algorithm suitable for BOCs(n,n) signal and BOCc(n,n) signal is also proposed. The correlation output of this algorithm has a higher main peak than the two algorithms mentioned above, so it is easy to be captured and has good noise immunity. The PUDLL tracking loop is a new unambiguous teqniqure used for BOCs(m,n) signal tracking, we built up this PUDLL tracking loop with Simulink tools to study the tracking performance of the algorithm. Two unambiguous tracking algorithms are proposed in this paper, the output of one proposed algorithm has a sharp main peak and only two small positive side peaks for all BOCc(m,n) signals. This algorithm also has a good performance of multipath mitigation. Another algorithm is suitable for MBOC(6,1,1/11) signal. Compared with ASPeCT algorithm, it has better tracking accuracy and ambiguity mitigating performance.