GPS satellite M code signal demodulation method based on combination of short code dispreading and timing recovery

Abstract

The invention provides a GPS satellite M code signal demodulation method based on combination of short code dispreading and timing recovery. The mutual promotion relation of short code dispreading and timing recovery is utilized, the signal-to-noise ratio threshold of demodulation can be effectively reduced, the antenna aperture is equivalently reduced, and the construction cost is saved. Firstly, the carrier frequency and carrier phase of a GPS satellite navigation signal are obtained through a typical carrier estimation method, carrier recovery and IQ separation are conducted, and extraction of a GPS M code signal is further achieved through band-pass filtering; and short code decoding is performed on the GPS M code signal to obtain coding gain, timing synchronization is performed by adopting blind processing for the first time on the basis, M code streams including innovation of the M code signals is solved after judgment, and the innovation is fed back to a front end to perform timing synchronization operation on the signals again. The timing synchronization precision can be improved.

Description

technical field [0001] The invention belongs to the technical field of satellite system monitoring and maintenance, in particular to a GPS satellite M code signal demodulation method based on the combination of short code despreading and timing recovery. Background technique [0002] With the modernization of GPS satellites, the M code of the GPS satellite navigation system has initially completed global networking, and the corresponding M code navigation receivers have also been put into use. Since the M code signal in the GPS signal is mixed with the C / A code and P code, under the condition that the code pattern and encryption method of the M code cannot be obtained, the local M code signal is mainly constructed by blind demodulation of the GPS signal. , to build a GPS M code receiving device. When performing blind demodulation on M-code signals, a large-caliber high-gain antenna is currently used to receive GPS satellite navigation signals to ensure demodulation performa...

AI Technical Summary

Problems solved by technology

However, the construction and maintenance cost of existing large-diameter antennas is relatively high, and demodulation technology of GPS signals with low signal-to-noise ratio is required to reduce the threshold of signal-to-noise ratio for demodulation, which is equivalent to reducing the antenna diameter and saving construction costs.

Images