A method for capturing CL codes of GPS L2C signals

Abstract

The invention provides a method for capturing CL codes of GPS L2C signals. According to the method, coarse acquisition is conducted on the GPS L2C signals with low signal to noise ratio, a time-frequency domain double-folding technology is adopted in the coarse acquisition process, data length is compressed, and then the folding section where a synchronization pseudo code phase position is placed is obtained through FFT circular correlation operations and threshold detection; the FFT circular correlation operations and threshold detection are adopted in the refined acquisition process, an accurate pseudo code phase position is obtained, and the entire acquisition is completed. By the adoption of the method, by the way of folding, the CL codes with large code length are shortened, so that the number of points of each FFT operation are greatly decreased, meanwhile, coherent integration time is prolonged, and precision is improved; by the way of double-folding, the acquisition is divided into the coarse acquisition and the refined acquisition, detection time is shortened, detection precision is improved, and high practical value is achieved.

Description

technical field [0001] The invention belongs to the technical field of wireless communication, in particular to a method for capturing CL codes of GPS L2C signals. Background technique [0002] In today's era, the application range of GPS (Global Position System, Global Positioning System) has penetrated into many fields such as surveying and mapping, communication, military, aerospace, electric power, remote sensing, etc., and all walks of life have higher requirements for its application. GPS signals include different frequency bands, among which the C / A civilian code contained in the L1 frequency band is most commonly used. However, the application of civilian L1 signals is more and more limited by conditions, such as the signal receiver is difficult to capture and track the signal under the condition of low signal-to-noise ratio with weak signal and strong interference noise. The low signal-to-noise ratio environment is one of the main environments where human activitie...

AI Technical Summary

Problems solved by technology

[0004] However, there are the following problems in the capture of L2C signals: first, if the capture method of the original L1C / A code is still used for capture, its accuracy and calculation time cannot be satisfied by the current hardware conditions

Secondly, at present, there are few public schemes at home and abroad and there are different problems. Among them, the main scheme is to first capture the CM code and then assist the CL code capture. However, once this scheme is under the condition of low SNR, the CM code capture will be more difficult. Difficult to complete; there is also an extended folded copy code capture technology for CL code capture, this scheme can use FFT to achieve fast and direct capture of CL codes without the assistance of CM codes, which saves time, but makes noise and The cross-correlation interference increases, which greatly reduces the sensitivity of the signal

Images