AIS baseband signal receiving system and method suitable for satellite-borne environment

A baseband signal and receiving system technology, applied in the modulation carrier system, frequency modulation carrier system, transmission system, etc., can solve problems such as limited coverage of shore-based AIS, low signal-to-noise ratio, and inapplicability of AIS signals

Active Publication Date: 2021-07-13
UNIV OF ELECTRONICS SCI & TECH OF CHINA
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0003] Due to the limited coverage of traditional shore-based AIS, and the high cost and difficult maintenance of base stations in some special areas, space-borne AIS can effectively solve the problems faced by shore-based AIS, but satellite channels have limited power, large interference, and signal Low noise ratio, the traditional AIS receiver has a simple structure, cannot resist large frequency deviation, and has low receiving sensitivity, so it is not suitable for AIS signal reception in the spaceborne environment

Method used

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  • AIS baseband signal receiving system and method suitable for satellite-borne environment
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  • AIS baseband signal receiving system and method suitable for satellite-borne environment

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Embodiment 1

[0071] like figure 1 As shown, the present invention provides a kind of AIS baseband signal receiving system that is applicable to space-borne environment, comprises the local signal generation module that connects in sequence, signal detection and frame synchronization module, signal phase stripping module, filter synchronization module and based on frequency search and The maximum likelihood demodulation module for confidence calibration; the local signal generation module is used to use the 24bits training sequence and 8bits start mark contained in the AIS message as the synchronization sequence of the signal, and perform GMSK modulation on the synchronization sequence to obtain local I and Q signals ; The signal detection and frame synchronization module is used to perform cross-correlation calculations based on the phase variation of the local I and Q signals to obtain the initial sample point of the signal; the signal phase stripping module is used to analyze the local si...

Embodiment 2

[0080] like figure 2 As shown, the present invention provides a kind of AIS baseband signal receiving method applicable to spaceborne environment, and its implementation method is as follows:

[0081] S1, local signal generation: use the 24bits training sequence and 8bits start mark contained in the AIS message as the synchronous sequence of the signal, and carry out GMSK modulation to the synchronous sequence to obtain the local I, Q signal, and its implementation method is as follows:

[0082] S101, using the 24bits training sequence and the 8bits start mark contained in the AIS message as the synchronization sequence of the signal, and performing differential encoding processing on the synchronization sequence;

[0083] S102. Use a Gaussian low-pass filter to smooth the phase path of the differentially encoded signal;

[0084] S103. Integrate the smoothed signal;

[0085] S104. Using GMSK modulation, taking cosine and sine respectively from the integrated signal phase to...

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Abstract

The invention provides an AIS baseband receiving system and method suitable for a satellite-borne environment, and belongs to the technical field of maritime communication, and the AIS baseband receiving system comprises a local signal generation module, a signal detection and frame synchronization module, a signal phase stripping module, a filtering synchronization module and a maximum likelihood demodulation module based on frequency search and confidence coefficient calibration which are connected in sequence. In the invention, the signal detection and frame synchronization part adopts a cross-correlation algorithm based on phase variation to determine whether useful signals exist and determine the initial position of the signals, the carrier synchronization part adopts an FFT (Fast Fourier Transform) algorithm to obtain initial estimation of frequency and phase, and the demodulation part adopts coherent demodulation of frequency search, ML (Markup Language) demodulation, confidence coefficient calibration and strong error correction. By adopting the structure, the satellite-borne AIS signal receiver can resist larger frequency offset and has high receiving sensitivity at the same time.

Description

technical field [0001] The invention belongs to the technical field of maritime communications, and in particular relates to an AIS baseband signal receiving system and method suitable for a spaceborne environment. Background technique [0002] The ship automatic identification system (AIS) can automatically receive and send important information such as the speed, position, and course of the ship. Therefore, AIS plays an important role in avoiding collisions between ships, reducing marine damage incidents, ensuring ship navigation safety, and promoting marine traffic management. important role. [0003] Due to the limited coverage of traditional shore-based AIS, and the high cost and difficult maintenance of base stations in some special areas, space-borne AIS can effectively solve the problems faced by shore-based AIS, but satellite channels have limited power, large interference, and signal Due to the characteristics of low noise ratio, the traditional AIS receiver has a...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H04B7/185H04L27/00H04L27/10H04L27/12H04L27/14
CPCH04B7/18513H04B7/18517H04L27/0014H04L27/106H04L27/12H04L27/14H04L2027/0026
Inventor 李桓朱继飞杨鍊王坚朱闲省
Owner UNIV OF ELECTRONICS SCI & TECH OF CHINA
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