Method and system for capturing weak GNSS (Global Navigation Satellite System) signal under condition of large-scale frequency deviation

A technology of frequency offset and signal acquisition, applied in the field of global navigation satellite systems, which can solve the problems of inapplicability of weak navigation signals and affecting the acquisition performance, etc.

Active Publication Date: 2011-08-24
TSINGHUA UNIV
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

Code Doppler will cause relative slippage of the code phase between different signal segments, so that the correlation peaks of different signal segments cannot be accumulated on the s

Method used

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  • Method and system for capturing weak GNSS (Global Navigation Satellite System) signal under condition of large-scale frequency deviation
  • Method and system for capturing weak GNSS (Global Navigation Satellite System) signal under condition of large-scale frequency deviation
  • Method and system for capturing weak GNSS (Global Navigation Satellite System) signal under condition of large-scale frequency deviation

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Embodiment

[0120] In this embodiment, the carrier frequency is 1575.42MHz, the sampling rate is 62MHz, the intermediate frequency is 46MHz, the pseudo-code rate is 10.23Mchip / s, the coherent integration time is 2ms, the number of non-coherent accumulations is 10, and the carrier frequency range to be searched is -5kHz Taking 5kHz as an example, further illustrate the implementation steps of the weak GNSS signal acquisition method under the large-scale frequency offset of the present invention:

[0121] 1. According to the coherent integration time of the receiver, the number of non-coherent accumulations, the carrier frequency, and the sampling rate, determine that the step size for the rough search of the carrier frequency is 1270 Hz.

[0122] 2. Divide the carrier frequency range to be searched into 8 carrier frequency cells at intervals of 1270 Hz. Note that the frequencies of these carrier frequency cells are respectively -5000+1270k (k=0, 1, 2, . . . , 7).

[0123] 3. According to ...

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Abstract

The invention discloses a method and a system for capturing a weak GNSS (Global Navigation Satellite System) signal under the condition of large-scale frequency deviation. The method comprises the following steps of: according to a pre-detection integration time, a carrier frequency and a sampling rate, determining a maximum carrier frequency searching step; dividing the whole frequency range to be searched into a plurality of carrier frequency units according to the maximum frequency searching step to realize rough search of the carrier frequency; mapping a received satellite signal onto each carrier frequency unit and regulating a local pseudo code rate according to the carrier frequency units so as to reduce the influence of code Doppler; calculating correlation in a flexible zero-padding mode through FFT (Fast Fourier Transform)/IFFT (Inverse Fast Fourier Transform) so as to realize code phase parallel search; and carrying out FFT operation on different correlation values corresponding to the same code phase so as to fulfill the aim of carrying out fine search on the carrier frequencies in the carrier frequency units. By the method and the system, a capturing speed and a capturing sensitivity of a receiver can be improved, so that the receiver completes the work of capturing a weak navigation signal pseudo code under the condition of the large-scale frequency deviation.

Description

technical field [0001] The invention relates to the technical field of Global Navigation Satellite System (GNSS), in particular to a weak GNSS signal acquisition method and system thereof under large-scale frequency offset. Background technique [0002] Global Navigation Satellite System (GNSS) mainly includes Global Positioning System (GPS) (United States), Global Navigation Satellite System (GLONASS) (Russia), Galileo Navigation Satellite System (GALILEO) (EU) and Beidou Global Navigation System (COMPASS) (China) ). These systems all broadcast satellite signals to users around the world by way of code division multiple access. In this way, the user must receive the satellite signal normally after completing the pseudo-code capture. In environments such as cities, mountains, and forests, satellite signals are often blocked by surrounding buildings, vegetation, etc., the signal will become very weak, and it will become very difficult to capture pseudo codes. Furthermore, ...

Claims

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Application Information

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IPC IPC(8): G01S19/24G01S19/30
Inventor 李洪陆明泉冯振明
Owner TSINGHUA UNIV
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