Method for rapidly capturing Beidou satellite signal based on FFT

Abstract

The invention discloses a method for rapidly capturing a Beidou satellite signal based on FFT. The method comprises steps of determining a local carrier frequency and a search step according to the range of the intermediate frequency and the Doppler frequency shift for receiving the Beidou satellite signal, generating a local carrier signal and performing a carrier-removing operation on the input signal to generate a mixed signal x1 (n); dividing the x1 (n) into P parts and subjecting each part to FFT calculation to obtain the frequency domain result Xi (k); dividing the Beidou satellite signal I branch ranging code CB2I code h1 (n) into P parts for the FFT calculation and performing the conjugate operation to get the frequency domain results Hi * (k); obtaining the frequency domain multiplication result Y1 (k) by the fusion algorithm; performing the IFFT operation on the frequency domain multiplication result Y1 (k) to obtain the time domain correlation result y1 (n); detecting whether there is a peak exceeding a threshold in the time domain correlation result y1 (n); and when the peak exceeds the threshold, indicating that the capture succeeds. The fusion algorithm of the invention is simple and easy to implement, the satellite signal is quickly captured without increasing the cost of the algorithm resources, and the acquisition algorithm is realized on the resource-limited embedded platform.

Description

technical field [0001] The invention belongs to the technical field of satellite navigation, and in particular relates to an FFT-based fast acquisition method of Beidou satellite signals. Background technique [0002] The Beidou satellite navigation system is an independent global satellite navigation system that China is implementing, and it has been gradually put into use. With the completion of the "Beidou Ground-Based Augmentation System", the positioning accuracy will be improved from the meter level to the sub-meter level and centimeter level, which can provide users with lane-level navigation and will be widely used in future driverless vehicles . [0003] Satellite positioning receivers can receive satellite signals broadcast by satellites around the world and provide users with position and navigation information through demodulation and calculation. Satellite positioning receivers can be divided into hardware receivers and software receivers. Compared with tradi...

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Problems solved by technology

Although the effect of fast capture can be achieved, the resource consumption of the algorithm will also increase at the same time, which is not conducive to the implementation of the algorithm on an embedded platform with limited resources

Document 2 "Joint acquisition of CM and CL codes for GPS L2civil (L2C) signals. (Proceeding of the ION 61st Annual Meeting. 27-29 June 2005, Cambridge, pp: 553-562 .(The 61st Annual Conference of

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