Coherency evaluation of GNSS MBOC pilot and data signal in joint tracking

摘要

The MBOC signal uses a modulation in which the pilot and the data signals are separated. However, these modulation methods have evolved a variety of joint receiving algorithms. The paper introduces the optimal design strategy for MBOC signal joint tracking, in which the amplitude and phase outputs in the loop phase discriminator are linear composite with the weight coefficients. According to the different modulations of each GNSS system, these composite coefficients are determined by the signals modulation phase relationship and power relationship. Through the BDS data verification, the advantages of joint tracking are demonstrated. The influences of signal coherency in the joint tracking process are analysed. The coherencies of between each signal code and code-to-carrier in GPS L1C, BDS B1C, and GALILEO E1C signals are evaluated by high carrier-to-noise ratio signal, which is acquired with the National Time Service Center CAS 40-metre antenna signal in space quality assessment system. The results verify the GNSS signal in space meets joint tracking requirements.