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A receiving method, receiver and communication satellite of a ship automatic identification system

A technology for automatic identification and reception of ships, applied in the field of ship satellite communications, can solve the problems of small Doppler frequency offset, low signal-to-noise ratio of AIS signals, slow relative running speed, etc., and achieves excellent demodulation and decoding performance, improved Demodulation and decoding performance, the effect of reducing frame error rate

Active Publication Date: 2021-08-10
SHANGHAI SPACEFLIGHT INST OF TT&C & TELECOMM
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, AIS spaceborne receivers are facing new technical problems: (1) In land / sea-based AIS systems, the relative speed between ships and between ships and shore base stations is slow, resulting in Doppler frequency shift Therefore, the existing AIS signal demodulation algorithm does not consider Doppler frequency offset as a main performance factor
However, for spaceborne receivers, due to the long transmission distance and large link loss of AIS signals, the signal-to-noise ratio of AIS signals received by satellites is low, and the performance requirements for demodulation algorithms are high. The demodulation performance is relatively poor under the signal-to-noise ratio

Method used

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  • A receiving method, receiver and communication satellite of a ship automatic identification system
  • A receiving method, receiver and communication satellite of a ship automatic identification system
  • A receiving method, receiver and communication satellite of a ship automatic identification system

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Embodiment 1

[0098] see image 3 , the present embodiment provides a method for receiving an automatic identification system for ships, comprising the following steps:

[0099] S1: Receive the AIS radio frequency signal sent by the ship automatic identification system, and directly sample the AIS radio frequency signal to obtain the AIS baseband signal;

[0100] S2: Perform frame synchronization on the AIS baseband signal to determine the exact starting position of the data of the AIS baseband signal;

[0101] S3: Obtain carrier frequency estimation and timing error estimation of the AIS baseband signal according to the AIS baseband signal, and synchronize the AIS baseband signal according to the carrier frequency estimation and timing error estimation;

[0102] S4: The cyclic redundancy check error correction decoder demodulates and decodes the AIS baseband signal to obtain the message content in the AIS radio frequency signal.

[0103] Now specifically describe this embodiment in detai...

Embodiment 2

[0197] see image 3 , the present embodiment provides a receiver based on the ship automatic identification system of embodiment 1, including: a radio frequency front-end processing module and a baseband signal processing module, the baseband signal processing module includes a frame synchronization unit, a preprocessing module, a cyclic redundancy check error correction decoder;

[0198] The RF front-end processing module is used to receive the AIS RF signal sent by the ship automatic identification system, and directly sample the AIS RF signal to obtain the AIS baseband signal;

[0199] The frame synchronization unit is used for frame synchronization of the AIS baseband signal to determine the exact starting position of the data of the AIS baseband signal;

[0200] The preprocessing module is also used to obtain carrier frequency estimation and timing error estimation of the AIS baseband signal according to the AIS baseband signal, and synchronize the AIS baseband signal ac...

Embodiment 3

[0288]This embodiment provides a communication satellite based on the automatic ship identification system of the second embodiment, and the communication satellite adopts the receiver of the automatic ship identification system as required by any one of the second embodiment.

[0289] The communication satellite of this embodiment is equipped with a receiver of the ship automatic identification system, which can realize communication with the ship and identification of the ship, and can monitor and track ships around the world in real time through networking satellites, thereby ensuring the navigation safety of ocean-going ships , where the communication satellite has the following technical advantages:

[0290] In this embodiment, the AIS baseband signal is synchronized by carrier frequency estimation and timing error estimation, and the AIS baseband signal is demodulated and decoded by a cyclic redundancy check error correction decoder, which solves the problem of large Dopp...

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Abstract

The invention discloses a receiving method, a receiver and a communication satellite of a ship automatic identification system. Wherein, the receiving method includes the following steps: AIS radio frequency signal receiving, filter amplification, analog-to-digital conversion, multi-stage orthogonal down-conversion and decimation filtering, storage, constant false alarm rate inspection, carrier synchronization, matched filtering, symbol synchronization, and whitening filtering , demodulation and decoding; the receiver includes a radio frequency front-end processing module and a baseband signal processing module, and the radio frequency front-end processing module is used to perform intermediate frequency filtering and power amplification, radio frequency sampling, quadrature down-conversion and decimation filtering on the received radio frequency signal to obtain the baseband signal , the baseband signal processing module is used to detect, synchronize, demodulate and decode the AIS message in the AIS baseband signal. The invention has the technical characteristics of excellent demodulation performance, resource saving and collision signal processing.

Description

technical field [0001] The invention belongs to the technical field of ship satellite communication, and in particular relates to a receiving method, a receiver and a communication satellite of a ship automatic identification system. Background technique [0002] Mutual communication and identification between ships is the premise of maritime navigation safety and ship traffic management. In order to avoid the loss of human life and property and the pollution of the marine ecological environment due to ship collisions, the Automatic Identification System (AIS) came into being. AIS works in the maritime VHF frequency band (30MHz~300MHz). At the same time, due to the limited height of shore-based and ship-borne antennas, the AIS transmitter can only cover an area with a diameter of about 40 nautical miles. With the rapid development of social economy, economic, trade and political exchanges between countries are becoming more and more frequent. The increase in the number of ...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H04B7/185H04L1/00H04L27/00H04L27/26
CPCH04B7/18517H04L1/004H04L27/0014H04L27/2656H04L27/2657H04L2027/0026
Inventor 周昊苏陆文斌吕振彬周雷曾媛秦夷朱秋菊
Owner SHANGHAI SPACEFLIGHT INST OF TT&C & TELECOMM
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