FPGA Design And Implementation Of QPSK Modulation And Demodulation System

Software defined radio with its flexible configuration, wide applicable range, goodportability, flexible and convenient upgrade, a variety of compatible modecharacteristics has become a hot topic in the field of modern communication. QPSKdigital modulation system with strong anti noise ability, more suitable for multi-usertransmission and other quality characteristics, become the modulation and demodulationtechnology is widely used in the wireless communication technology. This thesis is touse the method of the realization of software defined radio modulation anddemodulation of QPSK has very wide application value.This thesis introduces the basic principle of QPSK modulation and demodulationtechnology, provides the theoretical basis for the design and analysis of the subject. Theoverall structure of the system are given, modulation end by using numericallycontrolled oscillator and shaping filter, modulation is mainly using improved Costasloop to realize the carrier synchronization, symbol synchronization of the Gardner loop,and the design principle of each module described in detail. On this basis, establish thesimulation model of the modulation and demodulation module using Matlab software,and by observing the simulation waveform, analyzes the influence of differentparameters on the system, to verify the feasibility of the design system, and it providesthe basis for the parameter selection in subsequent design. Finally, the VHDL hardwaredescription language to realize the modulation and demodulation system developed inthe QuartuesII environment, describes in detail the digital controlled oscillator, shapingfilter, timing synchronization loop and bit synchronization loop design process.In this thesis, based on the basic theory of QPSK modulation and demodulationsystem, the implementation of Matlab software simulation system, and finally the wholesystem is implemented on FPGA hardware platform, to achieve the desired results. Asthe integration of FPGA technology and communication technology in teaching, to lay a solid foundation.