An Effective Tracking Algorithm Based on Attenuation Kalman Filter for BOC Modulated Signals

Binary offset carrier (BOC) modulation, which is widely used in global navigation satellite systems (GNSS), realizes spectrum separation and frequency band sharing. However, a little amplitude difference between the auto-correlation of main peak and side-peaks causes the ambiguous of acquisition and tracking and reduces anti-multipath ability. To solve this issue, this paper proposes a frequency phase early-late tracking method based on attenuation kalman filter (KFPELT) algorithm. Firstly, a group of carrier signals with early-late frequency are given by local NCO, and the demodulated signals are obtained by the multiplying of the carrier signals. Then, two groups of phase early-late pseudo-code signals given by local pseudo-code generator, which correlates with the demodulation signals. A loop filter based on attenuation kalman filter structure is designed to overcome the influence of multipath interference finally. Simulation results are presented to confirm the efficiency of the proposed algorithm.