A data demodulation and synchronization method for ship automatic identification system

A technology for automatic identification and data demodulation of ships. It is applied in transmission systems, digital transmission systems, FM carrier systems, etc. It can solve the problems of difficulty in synchronization and synchronization of burst short frame signals, and achieve cost savings, performance improvement, and simplified processing. effect of the process

Active Publication Date: 2019-12-20
BEIJING RES INST OF TELEMETRY +1
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  • Application Information

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Problems solved by technology

[0003] The purpose of the present invention is to overcome the deficiencies of the prior art and provide a data demodulation and synchronization method for the automatic identification system of ships. Synchronization accuracy of burst short-frame signals; in addition, the present invention adopts 2bit differential and Viterbi iterative judgment processing methods to simplify the data demodulation process and improve the performance of data demodulation. This method avoids the traditional 1bit differential demodulation method The complex processing and resource requirements of

Method used

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  • A data demodulation and synchronization method for ship automatic identification system
  • A data demodulation and synchronization method for ship automatic identification system
  • A data demodulation and synchronization method for ship automatic identification system

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Embodiment

[0040] In this embodiment, the data rate f of the ship's automatic identification system (AIS) b It is 9.6kbps, the modulation system is GMSK, the frame length is 256bit, the encoding method is NRZ-I, the data start is 0X7E, the data end is 0X7E, and the CRC check is 16 bits.

[0041] Adopt data demodulation of the present invention and synchronous method to process, concrete realization steps are as follows:

[0042] (1) ADC is used to sample and quantize the received signal to obtain received data. Wherein, the sampling rate of the ADC module in this embodiment is set to 9.6 MHz, so the number of sampling points corresponding to each data symbol in the sampled and quantized received data is N=1000.

[0043] (2) After the above received data is delayed by 2000 sampling points, it is multiplied by the current received data to obtain a mixed frequency signal.

[0044] (3) According to performance requirements, data extraction is performed on the above mixed frequency signal. W...

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Abstract

The invention discloses a data demodulation and synchronization method for a ship automatic identification system. In the method, data synchronization is realized through phase lookup based on a time domain sequence and verification-detection, so that the problems of difficulty in synchronizing burst short frame signals and poor synchronization difficulty can be solved, and the burst short frame signal synchronization accuracy is increased. Moreover, a processing way of 2bit difference and Viterbi iterative decision is adopted, so that a data modulation processing process is simplified, and the data demodulation performance is improved. Through adoption of the method, a complicated processing process and a resource demand of a conventional 1bit differential demodulation way are avoided.

Description

technical field [0001] The invention relates to the technical field of signal detection and demodulation, in particular to a data demodulation and synchronization method for a ship automatic identification system. The method is used for data demodulation and synchronization of burst and short frame signals. Background technique [0002] In February 2014, Recommendation ITU-R M.1371-5 of the International Telecommunication Union proposed the technical characteristics of the automatic identification system (AIS) using time division multiple access in the VHF maritime mobile frequency band, and the communication of the automatic identification system (AIS) system Corresponding provisions are made for the technical characteristics, but no corresponding provisions are made for the implementation methods. Especially for the realization of burst short frame signal synchronization and demodulation, there is no clear description of the realization. Contents of the invention [000...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H04L27/14H04L1/00
CPCH04L1/0054H04L1/0061H04L27/14
Inventor 曹巍吴鹏程郭立浩武光辉翟万涛
Owner BEIJING RES INST OF TELEMETRY
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