Analysis of signal distortion impact on code tracking bias for high-order BOC modulation

The high-order binary offset carrier (BOC) modulation can make full use of the allocated frequency spectrum resource to improve the compatibility with other GNSS signals in the same band, the anti-multipath capability and the code tracking accuracy. High-order BOC signals have been adopted by Galileo and COMPASS system. The distortions of high-order BOC signals and their impacts on signal performance need to be further explored. Based on the 2nd-order threat model of Evil Waveform (2OS EWF) proposed by ICAO, three types of threat mode-TMA, TMB, and TMC for BOC signals are modeled in this paper. The impacts of various models and parameters on the correlation function are analyzed. Next, the code tracking biases are calculated under different combinations of threat modes, distortion parameters, and correlator spacing. Finally, the optimum selections of correlator spacing for receivers are proposed based on simulation results.