Key Technologies Research Of Modulation And Demodulation System Based On Software Defined Radio

Because of flexibility,openness,programmability and scalability,Software Defined Radio (SDR) has become an important study architecture of communication field.Being a new design idea,SDR is widely used in the design of communication system in the world,and in the system of radio,radar,measurement and control. And in the commercialization age of 3G ,SDR led the idea.In research and design of digital communication system,one of the main objectives is to find a way of digital modulation,which spectrum utilization is high.Because of this,Quadrature Amplitude Modulation and Demodulation (QAM) is widely used in the field of modern communications. In the article,the simulation idea of modulation and demodulation system by software ,and the module researching base by FPGA is from the application of SDR.The author has detail analysis the QAM,and the key technologies of the system,such as frequency synthesizer,digital filtering,multi-rate signal processing, synchronization etc. First,analysis the principle of QAM,include two forms 4QAM and 16QAM,simply introduce the theory of SDR and the simulation and analysis software of SystemView ,ISE,ModelSim,and the hardware description language of Verilog HDL.And then established two systems based on QAM and simulated, compared by the software of SystemView.Last,the author has researched the key technologies modules of modulation and demodulation system,such as frequency synthesizer,digital filtering etc.She has simulated and analysis the system in the software environment. It got the expected purpose,which has reference for the whole design of radio system.The author has done much work.First,she searched a large number of materials,systematically study and researched the technology of SDR. Its basic idea is realize the hardware design of communication system by software. An important means of realize is Field-Programmable Gate Array (FPGA). For research the key technologies of modulation and demodulation system,the author depth study the design way of the software of SystemView and simulation tools based by FPGA. Based on FPGA,the author has achieved parameters verification by the theory,and simulation of the key moduls by the language of Verilog HDL in the simulation environment,which is constituted by the software of ISE and ModelSim. It laid the foundation of next hardware design.After resarching of this article,the author has learned about the architecture of the whole modulation and demodulation system,transmission and features of signal, familiarized the advantages of QAM,and hold the design way of key technologies of the system based on FPGA,the ability of analysis and design has improved.The experience laid the foundation of next communication rearch work.