Highly-dynamical weak signal GPS capturing method assisted by inertial navigation system

Abstract

The invention relates to a highly-dynamical weak signal GPS capturing method assisted by an inertial navigation system. The method comprises five steps that 1) capturing performances of coherent, non-coherent and differential coherent accumulation are compared, accumulation manners are selected and combined, and signal energy accumulation is reinforced; 2) coherent accumulation is carried out on input intermediate-frequency signals, the inertial navigation system and satellite ephemeris are used to estimate the Doppler parameter and code phase of received signals, and the frequency and the phase searching space are compressed; 3) Kalman filtering and smoothing are carried out on the estimation values of the Doppler parameters and the code phase, and a smoothing result is used to calculate the dynamic frequency / phase offset between local signals and the reception signals; 4) the dynamic offset amount of an output matrix of coherent accumulation is compensated by a cycled translation algorithm; and 5) non-coherent accumulation is carried out on the compensated output matrix, and an output result is compared with a threshold to deciding capture. The dynamic tolerance of GPS signal capturing is improved, and high-sensitivity GPS signal capturing can be realized in the highly dynamic environment.

Description

1. Technical field [0001] The invention relates to a high dynamic weak signal global positioning system (GPS, Global Positioning System) acquisition method assisted by an inertial navigation system, which belongs to the technical field of navigation. 2. Background technology [0002] The processing of the received signal by the GPS receiver includes capture, tracking, extraction of navigation text, and navigation calculation. Signal capture is the first and crucial step. With the complexity of the GPS application environment, the demand for high-dynamic and high-sensitivity GPS signal acquisition technology continues to increase. Its typical application is the autonomous orbit determination of geosynchronous orbit satellites and high-orbit satellites. High-sensitivity acquisition technology generally obtains high carrier-to-noise ratio gain by prolonging the signal accumulation time, but in a high-dynamic environment, the velocity and acceleration of the carrier vary widely,...

AI Technical Summary

Problems solved by technology

The FFT-based acquisition method can search for a wide range of Doppler frequency shifts, but due to the large amount of FFT calculations, the acquisition efficiency is low; the sequence estimation-based acquisition method requires a long enough observation time to accurately estimate the code sequence, which is not conducive to the rapid acquisition of signals ; The partial matched filter method correlates the signals in segments and performs FFT calculations. Although it reduces the amount of calculation in the frequency domain, it will lead to the decline of the carrier-to-noise ratio of the correlator output; the inertial navigation-assisted acquisition method uses the position and speed information output by the inertial navigation With the satellite ephemeris, the Doppler frequency shift of the received signal is estimated, and the captured frequency search range is obtained in advance, which shortens the signal capture time, but in the environment of high dynamics and low carrier-to-noise ratio, the relative acceleration between the carrier and the satellite causes The Doppler frequency shift rate is relatively large, and the offset between the local signal and the received signal continues to expand, making it difficult for the inertial navigation-assisted acquisition method to carry out long-term coherent accumulation of the signal, resulting in a significant attenuation of the acquisition sensitivity

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