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Beidou B1I signal capturing method based on variable length data accumulation

A technology of signal capture and long data, applied in satellite radio beacon positioning systems, measuring devices, instruments, etc., can solve problems such as correlation peak cancellation

Inactive Publication Date: 2021-05-18
NANKAI UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0008] (1) Use the delay multiplication method to strip the carrier and data codes to solve the problem of correlation peak offset caused by symbol bit jumps;

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  • Beidou B1I signal capturing method based on variable length data accumulation
  • Beidou B1I signal capturing method based on variable length data accumulation
  • Beidou B1I signal capturing method based on variable length data accumulation

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Embodiment Construction

[0020] The method of the present invention will be described in detail with reference to the drawings and embodiments.

[0021] (1) The carrier and data codes are stripped by the delay multiplication method to solve the problem of correlation peak cancellation caused by symbol bit hopping.

[0022] For the Beidou B1I signal, the intermediate frequency signal S(t) from the RF front end can be expressed as:

[0023] S(t)=D(t)C(t)sin(2πft)+W(t) (1)

[0024] Among them, D(t) is the data bit of the navigation message, D(t)=±1, for the D1 navigation message, D(t) also includes the NH code; C(t) is the ranging code, which is a cycle T o =1ms Gold code; f is the carrier frequency, due to the influence of Doppler frequency shift and local clock drift, f=f IF ±5KHz, f IF is the theoretical intermediate frequency value. W(t) is Gaussian white noise, subject to N(0,σ 2 )distributed. In the above formula, the carrier amplitude is normalized, and the corresponding noise power becomes ...

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Abstract

The invention discloses a Beidou B1I signal capturing method based on variable length data accumulation. The method comprises the following steps: stripping carrier waves and data codes by adopting a time delay multiplication method, and solving the problem of correlation peak offset caused by sign bit hopping; in a long-time coherent integration process, searching for Doppler frequency shift of the ranging code is completed by controlling the length of an accumulated data block; adopting an FFT parallel capture algorithm for the accumulated signal to realize the detection of the ranging code phase; and determining a carrier frequency offset range according to the searched ranging code frequency offset, and estimating the carrier frequency offset by adopting linear frequency modulation Z transformation. According to the method, in long-time coherent integration, the ranging codes are periodically superposed, so that the data length is reduced, and the calculation amount is reduced; and compared with a traditional coherent integration method, a non-coherent integration method and a differential coherent integration method, the method for searching the frequency offset of the ranging code by controlling the length of the accumulated data block has the advantages that the capturing probability is obviously improved, and the practicability is very high.

Description

technical field [0001] The invention relates to a Beidou B1I signal acquisition method based on variable-length data accumulation. Background technique [0002] In the process of receiving Beidou satellite signals, the first step is to complete the signal capture. We need to obtain the approximate carrier frequency offset and ranging code phase through capture to provide initial parameters for subsequent signal tracking. In order to capture weak satellite signals, it is necessary to obtain sufficient gain through long-time coherent integration. However, in the process of extending the coherent integration, a jump of the sign bit may be introduced, resulting in cancellation of the correlation peak. The higher the data code rate of the signal, the easier it is to introduce sign bit jumps in the process of coherent integration. For GPS L1 signal, its data code rate is 50bps. For the Beidou B1I signal, the data code rate of the D1 navigation message is 50bps, and after secon...

Claims

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Application Information

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IPC IPC(8): G01S19/29G01S19/30
CPCG01S19/29G01S19/30
Inventor 吴虹杨梦焕杨海效彭鸿钊陈琢乔红玉
Owner NANKAI UNIV