Table look-up method-based Beidou signal high-precision capturing method

Abstract

The invention relates to a table look-up method-based Beidou signal high-precision capturing method and belongs to the technical field of satellite navigation. The method comprises the following steps that: step 1, satellite signal pseudo codes are stripped; step 2, FFT is performed on the signals; step 3, a threshold value is set; step 4, an FFT output main peak value is compared with the threshold value, and if the FFT output main peak value is higher than the threshold value, capture is successful, and captured Doppler frequency shift is fd; step 5, an FFT output secondary peak value is compared with the threshold value, and if the FFT output secondary peak value is higher than the threshold value and is adjacent to a main peak position, Doppler frequency shift can be corrected, otherwise, fd is taken as a capture result; step 6, table look-up is performed with the ratio of an FFT output main peak to an FFT output secondary peak adopted as an address, so that a correction value fx is obtained; and step 7, a position relation between the main peak and the secondary peak is judged, if the secondary peak is on the left side of the main peak, corrected Doppler frequency shift is fd-fx, otherwise, the corrected Doppler frequency shift is fd+fx. The method is applied to a Deidou signal software receiver and can effectively improve the capture precision of the Doppler frequency shift under the condition that computational load is almost not increased.

Description

technical field [0001] The invention relates to a high-precision acquisition method of Beidou signals based on a look-up table method, and belongs to the technical field of satellite navigation. Background technique [0002] With the rapid development of the Beidou satellite navigation system, the use of Beidou satellites for high-precision navigation and positioning has become a research focus in recent years. Signal acquisition is the key technology in the Beidou system software receiver, which captures the signal from three dimensions of PRN code (pseudo-random noise code), pseudo-code phase and Doppler frequency shift. Since the noise contained in the captured satellite signal is Gaussian white noise, the maximum likelihood frequency estimation value of a single complex exponential waveform is at the peak position of the discrete Fourier transform (DFT) of the received signal. To be more suitable for computer operation, Fast Fourier Transform (FFT) is usually used for s...

AI Technical Summary

Problems solved by technology

In the existing high-precision capture technology, there is no effective high-precision capture method with a small amount of calculation, which causes the existing high-precision capture method to consume too much computing resources

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