GPS L1 rapid and accurate capturing method and device and computer storage medium

Abstract

The invention provides a GPS L1 rapid and accurate capturing method. The method comprises the following steps: carrying out half-chip sampling and expansion on a spreading code; performing intermediate frequency down-conversion and resampling on the satellite data; performing frequency mixing on a carrier signal obtained by accumulating a plurality of local carrier sequences corresponding to a preset Doppler frequency group and the processed satellite data to complete Doppler down-conversion so as to obtain zero Doppler data; segmenting the zero Doppler data of 2T (T < = 10) milliseconds by taking 1 millisecond as the length, and respectively performing coherent accumulation on the data of the first T milliseconds and the last T milliseconds to obtain two segments of satellite data with the length of 1 millisecond; performing FFT operation, complex number multiplication and IFFT operation on the processed spreading code and satellite data to obtain a cyclic correlation result; respectively solving moduli of the two sections of cyclic correlation results, searching a maximum value in the two sections of cyclic correlation results, if the maximum value exceeds a preset threshold, judging that coarse capture is successful, and calculating a corresponding satellite signal code phase at the moment; if the maximum value does not exceed the preset threshold, updating the preset Doppler frequency group to perform the next group of Doppler capture; and determining the section in which the maximum value appears in the two sections of satellites with the length of T milliseconds, and selecting the section of satellite data to carry out Doppler accurate acquisition. According to the method, the Doppler acquisition precision is improved while the search speed is increased.

Description

technical field [0001] The present invention relates to the technical field of satellite navigation, in particular to a method and device for fast and accurate GPS L1 acquisition. Background technique [0002] How to perform fast acquisition and achieve accurate Doppler acquisition on the basis of fast acquisition are the problems that need to be solved in the design of modern GPS receivers. [0003] The signal acquisition of satellites is achieved by correlation search, usually using a cyclic correlation algorithm. It is necessary to search for Doppler frequencies one by one at certain frequency intervals in the entire frequency search range; especially when it is necessary to increase the coherent integration time to improve the acquisition signal-to-noise ratio When the frequency search interval needs to be reduced, the frequency search times will be further increased. Therefore, reducing the frequency search times can achieve fast acquisition; while reducing the frequen...

AI Technical Summary

Problems solved by technology

Therefore, in general, capture speed and capture accuracy are a pair of contradictions

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