All-digital receiving method for satellite-borne AIS

A receiving method and an all-digital technology, applied in digital transmission systems, shaping networks in transmitters/receivers, carrier adjustment, etc., can solve problems such as space-borne AIS receiving devices and methods that have not yet been found, so as to improve flexibility, The effect of improving the detection probability and improving the demodulation performance

Active Publication Date: 2016-07-13
NANJING UNIV OF SCI & TECH
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Problems solved by technology

The same type of spaceborne AIS receiving devi...

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  • All-digital receiving method for satellite-borne AIS
  • All-digital receiving method for satellite-borne AIS
  • All-digital receiving method for satellite-borne AIS

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Embodiment Construction

[0022] The FPGA-based spaceborne AIS receiving device of the present invention includes an FPGA hardware system 1 and an AIS signal processing and demodulation program 2 . FPGA hardware system 1 is a hardware platform for processing and demodulating AIS information, which is mainly composed of FPGA chip and peripheral clock, power supply, storage and communication interface and other devices. The AIS signal processing and demodulation program 2 is a program running on the FPGA hardware system 1, and mainly controls the space-borne AIS receiving device to process and demodulate the AIS signal transmitted by the ship-borne AIS transmitter. The receiving device directly performs high-speed sampling of the AIS RF analog signal, and then uses digital quadrature down-conversion and decimation filters to down-convert the mixed RF digital signal of AIS1 and AIS2 to the baseband according to the theory of software radio. Mixing technology finally separates the two signals. From the sh...

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Abstract

The invention provides an all-digital receiving method for a satellite-borne AIS.The method comprises the steps that a signal processed through radio frequency digitization and a local carrier are subjected to orthogonal frequency conversion and then filtered to acquire mixed baseband signals, and the mixed baseband signals are separated; burst detection is performed on separated one-way signals; after a frame header is detected, frequency offset estimation is performed, and frequency offset compensation is performed on the baseband signals on the basis of a frequency offset estimation result; a frame header sequence is selected as an input signal for symbol timing synchronization to acquire a symbol timing error estimation value, and optimal sampling point data is interpolated according to the symbol timing error estimation value; information demodulation is performed on the optimal sampling point data by adopting an incoherent Viterbi demodulation algorithm, a bit information sequence is verified on the basis of a cyclic redundancy check code, and an optimal sampling point sequence of a frame header symbol period and the frequency offset, the amplitude and the initial phase of the verified bit sequence are estimated; a demodulation signal is recovered on the basis of frequency offset, amplitude and initial phase estimation values; the recovered strong signal is subtracted from the separated mixed baseband signals.

Description

technical field [0001] The invention relates to a wireless digital communication technology, in particular to a satellite-borne AIS all-digital receiving method. Background technique [0002] Ship Automatic Identification System (AIS) is a kind of ship navigation equipment based on self-organizing time division multiple access (SOTDMA) communication protocol, which transmits and receives ship dynamics, static information, navigation information and safety information. During the navigation of the ship, collision avoidance can be effectively avoided by receiving the AIS signals issued by each other. The International Maritime Organization stipulates that all international voyage ships of 300 gross tonnage and above, and non-international voyage ships of 500 gross tonnage and above, as well as all passenger ships, must be equipped with this system. The International Telecommunication Union (ITU) also allocates two channels to AIS in the VHF frequency band, namely CH87B (AIS1,...

Claims

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Application Information

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IPC IPC(8): H04L27/00H04L27/144H04L1/00H04L25/03
CPCH04L1/0054H04L25/03019H04L27/0014H04L27/144H04L2027/0026
Inventor 李鹏邹正芮义斌谢仁宏郭山红
Owner NANJING UNIV OF SCI & TECH
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