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Fast GPS L2C CM code capturing method

A fast, local code technology, applied in the field of satellite navigation, can solve problems such as implementation difficulty and signal-to-noise ratio loss

Inactive Publication Date: 2013-12-18
SHANGHAI JIAO TONG UNIV +1
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Problems solved by technology

If you want to correct the ionospheric transmission delay by receiving dual-frequency signals to obtain more accurate positioning results, you can only use the so-called codeless or semi-codeless technology to process the signal, which not only has the loss of signal-to-noise ratio, but also has a large implementation cost. difficulty

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  • Fast GPS L2C CM code capturing method
  • Fast GPS L2C CM code capturing method
  • Fast GPS L2C CM code capturing method

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Embodiment Construction

[0050] The present embodiment provides the GPS L2C CM code fast acquisition method, is characterized in that, comprises the following steps:

[0051] 1) Selecting the CM code as the local code, sampling the local code with the same frequency as the input signal, and folding the sampled local code in segments;

[0052] 2) performing local down-conversion on the input signal to obtain the baseband data of the input signal, intercepting the baseband data of the input signal, and the intercepted input signal is consistent with the sampled local code length;

[0053] 3) Perform fast Fourier transform on the intercepted input signal and the adopted local code respectively to complete the transformation from the time domain to the frequency domain, and search the code phases of the intercepted input signal and the local code to obtain several coherent values ;

[0054]4) A threshold is set, and the maximum coherence value among the several coherence values ​​is selected to compare w...

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Abstract

The invention provides a fast GPS L2C CM code capturing method. The method comprises the steps of carrying out full-period segmented collapsing on a local code sequence, capturing a data section as long as a local signal from received signal data, carrying out phase search by means of FFT algorithm circular correlation, carrying out theoretical analysis and formula derivation of thermal noise and collapsing noise, obtaining an accurate noise empirical formula by combining with experimental data, providing a reasonable threshold setting scheme to determine a code phase primarily according to the analysis of the signal to noise ratio of the signal, and carrying out time domain coherent processing on the primarily determined code phase after capturing succeeds to obtain a final code phase. According to the fast GPS L2C CM code capturing method, the searching speed of the phase of an L2C signal CM code is improved greatly, the phase of the CM code can be determined fast, and FFT computing amount is reduced greatly.

Description

technical field [0001] The invention relates to the field of satellite navigation, in particular to a fast acquisition method of a GPS L2C CM code. Background technique [0002] The United States' Global Positioning System (GPS) has been improving since its inception. This is because civilian users require GPS to have better anti-interference performance, higher security and integrity; while the military requires that the military signals emitted by satellites have greater power and be separated from civilian signals. [0003] In order to enable GPS to better meet the increasing application requirements of military, civilian and commercial users, in 1999, the US government launched a GPS modernization plan. An important content of the plan is to add a new civilian signal, namely L2C (the L2civil) signal, on the L2 frequency point (1227.60MHz). [0004] So far, eight modern GPS Block IIR-M satellites have transmitted L2C signals. It is of great significance to effectively ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01S19/30
Inventor 陈新陆华
Owner SHANGHAI JIAO TONG UNIV
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