Research On Modulation And Demodulation Algorithm Of ASM Baseband And Implementation By FPGA

VHF Data Exchange System(VDES)is an enhanced and upgraded system of Automatic Identification System(AIS)in the field of maritime mobile services.With the growth of the maritime data communication needs,AIS gradually undertake the task of ship-shore data communication,which was developed to achieve mutual identification and avoid collisions of ships in the first place.This changing increased the risk of utilization and protection of VHF data link resources,and brought negative influence in navigation safety and maritime communication.After the integration,VDES,which is constituted by AIS,ASM and VDE,can tremendously alleviate the pressure of the AIS data communication at current stage.In order to meet the increasing demand of maritime communication as response to the World Radio Communication Conferences(WRC),this paper mainly studied the theory and implementation of Application-specific Message(ASM)channel in VDES.Based on a deep analyze of ITU-R M.2092 proposal,the article detailed introduced the parameter index of physical layer and link layer in ASM channel.In addition,the author built a complete set of mathematical models of ASM baseband data modulation and demodulation method--?/4 QPSK.According to the theoretical analysis,the ?/4 QPSK method is carried on the MATLAB software tool to simulate,and finished implementation on Xilinx FPGA platform.The paper divided the project into two parts of modulation and demodulation to present realization.It discusses the overall architecture first,and then the realization of each module is introduced in detail.To sum up,the project complete the basic requirements of ASM data modem processing.Moreover,it has developed a set of embedded real-time data display system on Zynq architecture,which is elaborated in the last section of the paper.The projects in this paper contain two aspects of MATLAB simulation and implementation based on FPGA platform.As to the FPGA part,it is developed by using Xilinx Company Vivado 13.4 system development kit,with Zedboard platform,Zynq series.Additionally,the paper bring up an innovative real-time data display system under AXI4 bus in Zynq architecture,which could separate the task into physical and application layers to fulfill.The results achieve anticipated goals,and have guiding impact to further development.