Abstract: The present disclosure discloses a Beidou signal tracking system with a nonlinear phase-locked loop. A nonlinear element and a low-pass filter are added behind a loop filter to adapt to an output from control of the loop filter, and then to control a phase of an output signal. An in-phase branch pre-filtering link is added before the loop filter to smoothly processing an input signal, and a loop filter of a third-order phase-locked loop assisted by a second-order frequency-locked loop is selected to ensure basic performance index of an algorithm. The in-phase branch pre-filtering link controls signal change of an in-phase branch signal within a reasonable range. The nonlinear element and the low-pass filter behind the loop filter, after proper selection of parameters, can make the phase-locked loop quickly lock within the range where the phase-locked loop could not be locked originally.

Abstract: Provided is a BeiDou navigation satellite B1C signal capturing method, including: mixing a digital intermediate frequency signal with a local intermediate frequency carrier signal to obtain a baseband signal; obtaining a local BOC-like signal on a data channel and a local BOC-like signal on a pilot channel; processing the local BOC-like signal on the data channel and the local BOC-like signal on the pilot channel to obtain a cross-correlation result of the data channel and a cross-correlation result of the pilot channel; performing a linear operation on the cross-correlation result of each of the two channels through a pseudo-correlation function generator to eliminate a secondary peak in the cross-correlation result of each of the two channels, and obtain an optimized cross-correlation result of each of the two channels; and capturing a satellite signal based on the optimized cross-correlation result of each of the two channels.