Signal demodulation method and system of satellite-borne automatic identification system (AIS)

An automatic identification system and signal demodulation technology, applied in the field of communication, can solve the problems of coherent demodulation performance degradation and difficult implementation

Active Publication Date: 2020-03-31
SPACE STAR TECH CO LTD
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Problems solved by technology

At present, the GMSK demodulation technology is mainly coherent demodulation technology, which needs to restore the carrier at the same frequency and phase as the modulation at the receiving end, which is difficult to realize and is very sensitive to the receiving frequency offset (Frequency Offset). There is a large frequency offset, which will lead to a sharp drop in coherent demodulation performance

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  • Signal demodulation method and system of satellite-borne automatic identification system (AIS)
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  • Signal demodulation method and system of satellite-borne automatic identification system (AIS)

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Embodiment Construction

[0050] In order to understand the characteristics and technical contents of the embodiments of the present application in more detail, the implementation of the embodiments of the present application will be described in detail below in conjunction with the accompanying drawings. The attached drawings are only for reference and description, and are not intended to limit the embodiments of the present application.

[0051] figure 1 A schematic flow chart of the AIS signal demodulation method provided by the embodiment of the present application, such as figure 1 Said, said method comprises the steps of:

[0052] S101: Perform Gaussian minimum frequency shift keying GMSK modulation on the AIS service information to obtain the AIS signal of the GMSK signal system; perform band-pass filtering, digital frequency conversion and low-pass filtering processing on the AIS signal of the GMSK signal system to obtain the AIS baseband signal.

[0053] Specifically, here, the signal receiv...

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Abstract

The embodiment of the invention discloses a technical scheme. The method comprises the following steps: performing GMSK modulation on AIS service information; performing band-pass filtering, digital down-conversion and low-pass filtering on the modulated AIS signal to obtain an AIS baseband signal; performing the frame header detection, frequency offset estimation, frequency offset compensation, matched filtering and Viterbi decoding on an AIS baseband signal to obtain the demodulation signal of the AIS baseband signal. According to the invention, the good demodulation performance of a coherent demodulation algorithm is maintained, the problems of carrier recovery and phase blind bit estimation in coherent demodulation are avoided, and compared with the coherent demodulation algorithm, theimplementation process is simpler. The error rate and the packet error rate of the finally obtained demodulated AIS baseband signal are low, and the requirement for demodulating the AIS signal can bemet.

Description

technical field [0001] The embodiments of the present application relate to the field of communications, and in particular to a signal demodulation method and system for an on-board automatic identification system (AIS). Background technique [0002] The Automatic Identification System (AIS, Automatic Identification System) works in the maritime very high frequency (VHF, Very High Frequency) frequency band, adopts the open system interconnection (OSI, OpenSystem Interconnection) working mode, and can work autonomously and continuously in all areas, using automatic Self-Organized Time Division Multiple Access (SOTDMA, Self-Organized Time Division Multiple Access) communication protocol is a ship navigation device that transmits and receives ship dynamics, static information, navigation information and safety information. During the ship's navigation, as the position, speed, course and other information change, AIS will update the data information sending and receiving in real...

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H04L27/38
CPCH04L27/38H04L27/3818
Inventor 于雪晖张晓曼孙婷婷梁利环张佳培
Owner SPACE STAR TECH CO LTD
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