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Many safety-critical applications that utilize the global navigation satellite system (GNSS) demand highly accurate positioning information, as well as highly integrity and reliability. Due to GNSS signals are easily distorted by the interferences or disturbances, the signal quality monitoring (SQM) is necessary to detect the presence of dangerous signal distortions. In this paper, we developed an SQM software for binary offset carrier (BOC) modulated navigation signals. Firstly, the models of BOC signal with ideal and distortion are presented respectively. Then the architecture of SQM software is proposed. Moreover, the effect of the white gaussian noise (WGN) and the front-end filter on the correlation peak of the receiver is analyzed. Finally, the biases induced by the signal distortion are evaluated. The experiments simulate the relationships between the code phase shift and the normalized correlation value in the case of the signal digital distortion and the analog distortion. The simulation results demonstrate that the proposed SQM method can effectively monitor the signal distortion and accurately estimate the correlation peak deviation caused by the distortion.

Abstract-This paper introduces a chip waveform distortion

Low-density parity check (LDPC) codes which have many encouraging characteristics, such as the lower complexities of the hardware implementation, closing to Shannon limit and no patent barrier, have gradually regained the interests of researchers. We present performance simulations in allusion to QC-LDPC codes. A fast double-recursion pipeline method which can significantly improve the encoding speed and a normalization min-sum algorithm are proposed in this paper. Simulations, hardware implementation and real test showed that QC-LDPC codes which has strong advantages on resource consumption, delay constraint and coding gain, could serves as an appealing alternative to new generation satellite navigation channel encoding and decoding.