The capture of Binary Offset Carrier (BOC) modulated signals is ambiguous. In order to solve the problem, a novel algorithm named decompose-compose based on the local BOC signals was proposed. Firstly, the local subcarrier signal was decomposed according to the order n of the local BOC signal. Secondly, the 2 n subfunctions of BOC signal were gotten by multiplying the pseudo-random code with the decomposed functions gotten from the first step. Then the 2 n subfunctions were respectively used to make correlation with the received BOC signals for obtaining the 2 n cross-correlation functions. Finally, the 2 n cross-correlation functions gotten from the last step were further processed according to the decompose-compose algorithm. The theoretical analysis and the simulation results show that, compared with Offset Quadratic Cross-Correlation (OQCC) algorithm, the proposed decompose-compose algorithm had the improvement of 21.51 dB and 3.4 dB in the Amplitude Separation Degree of Main and Side Peaks(ASDMSP) when the signals of BOC(1, 1) and BOC(2, 1) were captured. The experimental results show that the decompose-compose algorithm can effectively solve the ambiguous problem of BOC signals.

Focused on the elimination of multipath error in Global Positioning System (GPS), a multipath error elimination method based on the combination of integrity and deep coupling structure was proposed. Firstly, the GPS and Strapdown Inertial Navigation System (SINS) were constructed into a deep coupling structure. Then, pseudorange residual and pseudorange rate residual which came from the output of phase frequency detector were used as the test statistics. Secondly, according to that pseudorange residual and pseudorange rate residual subjected to Gaussian distribution, the detection threshold of pseudorange residual and pseudorange rate residual was calculated. Finally, the detection threshold was used to evaluate the test statistics, and the modified pseudorange residual and pseudorange rate residual were put into the Kalman filter. In the simulation comparison of the proposed method with the multipath error elimination method without integrity: the latitude error decreased by about 40 m, the yaw angle error decreased by about 4 degrees, the north velocity error decreased by about 2 m/s. In contrast to the traditional method of eliminating multipath errors (using wavelet filtering): the height error decreased by about 40 m, the pitch angle error decreased by about 5 degrees. The simulation results show that the proposed method based on integrity can effectively eliminate the positioning error caused by multipath (reflected in position error, attitude angle error and velocity error). Meanwhile, comparing to the traditional filtering method, it can more effectively reduce the positioning error caused by multipath.