Adaptive coherent accumulation joint acquisition method under GNSS weak signal

Abstract

The invention relates to an adaptive coherent accumulation joint acquisition method under GNSS weak signal, which belongs to the field of signal acquisition. The method preserves the performance of high acquisition probability of the prior coherent accumulation method and avoids the flip effect of navigation data in the piriorcoherent accumulation method. The method uses the coherent accumulation and the differential accumulation, and can detect the flip position of the navigation data in the process of acquisition. Before the flip of the navigation data is detected, the coherent accumulation method is used firstly. After the flip of the navigation data is detected, the differential accumulation method is used. Thus, the method has the advantages of high processing gains of the coherent accumulation and no flip effect of the navigation data on the differential accumulation. In addition, different from the threshold value detected by fixed acquisition in the traditional method, the adaptive coherent accumulation joint acquisition method adjusts the threshold value adaptively according to the noise of a received signal. Compared with the traditional method, the adaptive coherent accumulation joint acquisition method improves the detection probability, shortens the acquisition time and is suitable for accurate positioning in a weak signal environment.

Description

technical field [0001] The invention relates to the field of signal acquisition in global satellite navigation systems. Background technique [0002] The research and application of global navigation satellite system (GNSS) outdoor positioning technology has been very common. The first functional module of the GNSS receiver to process the signal is the acquisition module. It is used to detect whether a valid GNSS signal is received from the antenna end. A locally generated pseudo-random sequence (PRN) code needs to be synchronized with the received signal to despread the received signal. The acquisition module needs to estimate the PRN code phase difference and the carrier Doppler frequency shift between the local signal and the received signal at the same time, and these two estimations will be used in the subsequent tracking module of the receiver. [0003] The acquisition of GNSS signals is a two-dimensional search process, that is, the phase of the PRN code and the Do...

AI Technical Summary

Problems solved by technology

[0017] The correlation peaks obtained by the three accumulation methods are different, but each method has its own advantages and disadvantages

Coherent accumulation has the highest probability of capturing the peak because there is no square loss, but it is seriously affected by the navigation data flip with a period of 20ms

The flipping of navigation data cancels the effect of coherent accumulation and limits the length of coherent accumulation

Non-coherent accumulation accumulates the absolute value of the correlation result every ms, so there is no effect of navigation data flipping, but there is a square loss

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