Research On Carrier Synchronization In VDE-TER

The VHF Data Exchange System(VDES)is a maritime communications system developed on the basis of the Automatic Identification System(AIS).It is one of the core communications modes of IMO e-Navigation strategy.VDES includes AIS,ASM and VDE traffic channels.VDE channels are divided into two channels:VDE-TER and VDE-SAT.This thesis focuses on VDE-TER carrier synchronization in different modulation modes.The thesis firstly introduces the technical features of VDE-TER channel,the architecture and technical characteristics of VDES system,base on which builds VDE-TER simulation platform on Matlab platform.Based on the carrier synchronization performance index and carrier signal model,the phase synchronization and frequency synchronization processing methods and synchronization algorithms of VDE-TER carrier synchronization are mainly studied on this platform.Aiming at the carrier phase synchronization technique,we study the decision-directed estimation algorithm,the histogram estimation algorithm and the Viterbi estimation algorithm,including the theoretical model of the algorithm,the calculation and implementation method.Simulations are run to analyze and compare the performance of different phase synchronization algorithms.In the aspect of VDE-TER carrier frequency synchronization,we focus on data-assisted algorithms like M&M,L&R and other algorithms in frequency offset estimation and make use of the special structure of the training sequences to propose a frequency synchronization algorithm based on phase offset of Barker sequences and it's reverse sequences.The performance analysis and comparison of different frequency synchronization algorithms are also performed on the above simulation platform.Based on the work above,a VDE-TER carrier synchronization platform system based on the software defined platform is further established and a data aid synchronization scheme is proposed.Synchronization performance of frequency synchronization algorithm is studied in the actual channel on the software defined platform.Results show that,the double Barker code frequency offset estimation algorithm performs better than M&M algorithm and Fitz algorithm.The research content of this thesis is "Science and Technology of IMO e-Navigation Strategy and Development of China's e-Navigation Strategy"(2016-04)and "VDES System Research" of China Civil Aviation R&D Fund Project of China Academy of Aeronautical Technology(JMRH-THYT-2017001)part of the study.