Design And Implementation Of DSSS Range And Velocity Measurement System Based On FPGA

This thesis introduces a kind of spread spectrum ranging and velocity measurementsystem based on FPGA, the system is used to measure the distance and velocity ofsatellites and to communicate between satellites and base station of the ground at the sametime.The system designed in this paper includes the range and velocity measurementchannel and the remote control channel. The range and velocity measurement channelreceives two frames from the ground, calculates the pseudo range and Doppler frequency,and insert the pseudo range of uplink and Doppler frequency into the downlink frame formodulation. The remote control channel receiving signals from the ground station andaccomplish demodulation before sending the remote control signal to the remote controlunit.Through large number of theoretical analysis and verification, this thesis uses FPGAto realize the baseband of the system. According to the parameters of the system and theindex requirements of design and implementation, the system include modules of pseudorandom code modulation of data for transmitting, pseudo code acquisition and tracing ofreceiving signal, carrier tracking, data demodulation and the interface design of embeddedprocessor.This thesis first introduces the basic principle of spread spectrum communication anddescribed the structure of direct sequence spread spectrum communication system,explain how to use the basic principle of spread spectrum communication for measuringdistance and velocity, then according to index the system required, this thesis gives thedesign scheme of the whole system, then describes the realization of the system withFPGAlogic design.The whole system has been successfully completed and functioning well, it have reached the requirements of the design.