Beidou weak signal capturing method based on zero-padding algorithm and differential coherence algorithm

Abstract

The invention discloses a Beidou weak signal capturing device based on a zero-padding algorithm and a differential coherence algorithm. The Beidou weak signal capturing device based on the zero-padding algorithm and the differential coherence algorithm comprises a Beidou receiver antenna, a radiofrequency module and a baseband processing module. The invention further discloses a Beidou weak signalcapturing method based on the zero-padding algorithm and the differential coherence algorithm. The Beidou weak signal capturing method based on the zero-padding algorithm and the differential coherence algorithm comprises the following steps: carrying out mixed frequency down-conversion on a Beidou satellite signal received by the Beidou receiver antenna into intermediate frequency, and samplingto obtain a sampling signal; carrying out frequency mixing on the sampling signal and local carrier wave, carrying out zero padding on local pseudo codes by using the zero-padding algorithm, then carrying out correlation operation on the local pseudo codes and the sampling signal to obtain a correlation result; carrying out differential coherence operation on the correlation result, and carrying out integral summation operation for 10 milliseconds per time; and carrying out peak value detection on an integral result, and if the peak value exceeds a threshold value, acquiring a carrier wave Doppler frequency estimated value according to the position of the peak value so as to finish a capturing process. By the scheme, influence of NH code jumping and bit jumping can be greatly weakened, theintegral time is prolonged, and the signal to noise ratio is increased.

Description

technical field [0001] The invention belongs to the technical field of signal baseband processing of a satellite navigation receiver, and in particular relates to a Beidou weak signal acquisition method based on a zero-padding algorithm and a differential coherence algorithm. Background technique [0002] With the development of satellite navigation systems, the development of high-performance receivers has become a research hotspot at home and abroad, and the high-sensitivity receiver for weak signals is one of the hotspots. In recent years, many experts and scholars at home and abroad have carried out research on high-sensitivity GPS receivers. With the development of the Beidou navigation system, the high-sensitivity Beidou navigation receiver for weak signals has certain theoretical value and application prospects. [0003] Prolonging the coherent integration time is a commonly used method for high-sensitivity receivers to improve the signal-to-noise ratio, and at the s...

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Problems solved by technology

But extending the integration time is limited by data bit transitions:

[0004] The D1 navigation message broadcast by the Beidou MEO and IGSO satellite signals is re-coded and modulated with an NH code (New Hoffman code) with a rate of 1kbps, which can improve the resistance to narrow-band interference and improve the cross-correlation characteristics between satellite signals, but at the same time The coherent integration time is affected by the NH code phase jump, and the coherent integration time is limited to 1ms without removing the NH code

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