Research And Implementation Of Demodulation System Based On VDES

In recent years,Automatic Identification System(AIS)plays an essential role in ensuring maritime traffic safety,maintaining maritime traffic order and tracking ships.The space-based AIS has become an important tool for marine navigation and vessel data communication.However,with the rapid increase in the number of AIS vessels and the diversification of users' demands,the traffic density at sea becomes larger and larger,and the amount of data in maritime communications is also increasing.At the same time,the extensive application of AIS technology places a heavy burden on the AIS system.As a result,the existing AIS system will not be able to meet the needs of data switching in the future.In order to relieve the pressure of AIS data communication and ensure the integrity of the basic functions of AIS,the VHF Data Exchange System(VDES)came into being.The VDES system takes full advantage of the original intention and potential features of AIS system,and expands the compatibility of the existing AIS system,which can comprehensively strengthen the data transmission capability of maritime communication.The proposal of VDES system has attracted widespread attention of research institutions at home and abroad.This paper relies on the "VDES technology research" project cooperated by the aerospace institute and recommendations of VDES.In this paper,the key demodulation technology of VDES system is studied and analyzed in detail,and the simulation and implementation are carried out for the demodulation part of VDES system to provide appropriate data support.First of all,this paper introduces the background of VDES system,and expounds the research significance of VDES system and the research status at home and abroad.In addition,the system architecture and related core technology of VDES system are analyzed emphatically.Then,based on the proposals and recommendations of VDES,this paper focuses on the non-orthogonal multi-carrier modulation technology and the joint demodulation technology of collision signals in the VDES system.The simulation and performance analysis of the key algorithms and technologies are realized by using the MATLAB platform.Finally,according to the characteristics of the received signal,a design scheme of the demodulation system based on VDES is proposed.On the basis of the related specifications and core demodulation technology,the receiver of VDES is implemented modularly,which includes time-frequency frame synchronization algorithm,multi-carrier modulation technology and so on.Besides the simulation of the design scheme is carried out to verify the feasibility and rationality of the demodulation system.The purpose is to provide appropriate theoretical basis for the proposal.