Correlation Side-Peaks Cancellation Technique for Sine-BOC Signal Tracking

Abstract

With the development of GNSS systems, BOC modulation signal has been widely used in the modernized GPS, Galileo, and Beidou. BOC signal has the split power spectrum density (PSD), which has better compatibility with GPS C/A signal. Furthermore, the PSD of BOC signal has more high frequency components, which results in better code tracking performance and multipath mitigation performance than BPSK signal. Because of the sub-carriers, the autocorrelation function (ACF) of BOC modulation signal has a main peak and some side peaks. The traditional delay locked loop (DLL) may be locked on the side peaks of ACF, which causes the extra tracking error. In this paper, an unambiguous tracking method is proposed for BOC modulation signal. The received BOC signal is correlated with two different local reference signals with the tailored waveform to obtain correlation outputs. Then the correlation outputs are combined to eliminate side peaks and obtain the combined correlation with one peak. The early minus late power (EMLP) discriminator can be used to lock on the sole peak of the combined correlation function. This unambiguous tracking techniques has been analyzed for BOC (1, 1) signal in the simulation. The simulation results show that this technique can achieve the unambiguous tracking for BOC signal and maintain the same level of the tracking performance as the traditional tracking loop.