Applied Research In Experimental System For The Software Radio Adapt To Teaching And Studing

The main task of this project is to research partial key technique of the software radio,and to complete a experimental system adapt to teaching and studying based upon the DSP chips.The software radio is based on an open ,standardized, modularized, general platform .And all kinds of waveforms are achievable with software,which include frequence range, modulation signal, data type,security critical and communica- tion protocol.The wide Analog- Digital(A/D) conversion and Digital- Analog (D/A) conversion move to the antenna as close as possible by dowmloading software to the platform.This paper researches into a passband sampling theorem for multiplex signals,gives an algorithm to solve the least sampling rate and analyse the relation between the sampling rate and the Signal-to-Noise.It discusses the algorithm of quadrature modulation and demodulation about all kinds of signals and points out the advantage in the software radio.The method of digital up and down convert of frequncy is studied,which is very useful but realized difficu- ltly.And the models of multicenter transmitter and multicenter receiver are presented.The paper studies the identification of digital modulation about ASK,FSK,PSK and QAM.The relation between the identification error probability and the Signal-to-Noise is reviewed.And the synchronization technology is described,including carrier-frequency synchronization,bit synchronization and frame synchronization.In hardware design,we have finished a smaller platform of software radio based on DSP chips,which include transmitter and receiver .The transmitter is composed of a DSP chip and a D/A conversion,then the receiver is composed of another DSP chip and a A/D conversion .By this hardware platform , modulation and demodulation of ASK,FSK,DPSK,QPSK and QAM,and synchronization are finished.Then the communication system is realized.