A data-assisted method and system for estimating synchronization parameters of spaceborne AIS signals

Abstract

A data-assisted satellite-borne AIS signal synchronization parameter estimation method comprises that an antenna receives a radio frequency signal emitted by an earth ship AIS system and sends the radio frequency signal to a receiver; the receiver demodulates the received radio frequency signal into a baseband signal and inputs the demodulated radio frequency signal into an FPGA (field programmable gate array) data acquisition module; the FPGA data acquisition module subjects the received baseband signal to analog-digital conversion to obtain a digital baseband signal and inputs the digital baseband signal into a signal processing module; the signal processing module processes the received digital baseband signal to obtain correct AIS ship information and to send the correct AIS ship information into a data storage module; and the data storage module stores the received AIS ship information. The data-assisted satellite-borne AIS signal synchronization parameter estimation method has the advantages that under signal downsampling and by introducing the self-correlation operation and the maximum likelihood operation, the performance of large estimation range and small estimation error of frequency offset of the satellite-borne AIS signal can be achieved; and through the accumulation argument operation and the accumulation module value operation, high-accuracy timing estimation, phase shift estimation and amplitude estimation are achieved.

Description

(1) Technical field: [0001] The invention belongs to the field of ship automatic identification system (Automatic Identification System, AIS) communication technology, in particular to a data-assisted method and system for estimating a synchronization parameter of an on-board AIS signal. (two) background technology: [0002] In the spaceborne AIS receiver, there are often mixed signals of multiple channels. When separating the mixed signals and ensuring that other signals are not damaged, it is necessary to restore the signal more accurately on the basis of the known signal decoding sequence. , so a higher precision signal parameter estimation is required. This estimation method belongs to data-assisted synchronization parameter estimation. When the spaceborne AIS signal is separated, the estimation accuracy of this step is more demanding than that of blind estimation. [0003] Since the AIS signal is modulated by Gaussian Minimum Shift Keying (GMSK), the parameter estimati...

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Problems solved by technology

In the literature (Michael Rice, "Data-Aided Carrier Phase Estimation for GMSK", IEEE International Conference on Communications [J]. 2003 (5), 3560-3564), a data-assisted phase shift estimation is proposed. This technology mainly uses the maximum likelihood operation, but it can only be used for The phase shift is estimated, and the document (TuanFengWu, "NewData-AidedFrequencyEstimationAlgorithmBasedonDiscriminatorforGMSKSignals", Proceedingofthe2003InternationalConferenceon[J].2003,12(2):1706-1709) uses the original KAY working method and Fitz working method to estimate the frequency offset of the GMSK signal. 精度较低,不能达到星载AIS接收机的要求,(MICHAELRICE,“EstimationTechniquesforGMSKusingLinearDetectorsinSatelliteCommunications”,IEEETransactionsonAerospace&ElectronicsSystems[J].2007,4(43):1484-1495)和(WenliShen,“DataAidedSymbolTimingEstimationinSpace-TimeCodedCPMSystemsoverRayleighFadingChannels”,VehicularTechnologyConference[J ].2007,9(66):556-560) used autocorrelation and maximum likelihood calculation respectively, but the estimation range is small, and only the frequency offset within 1KHz can be estimated

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