Research On Direct Sequence Spread Spectrum Receiver Based On Software Radio

Recently, how to use the spectrum effectively and how to adapt to all kinds of application environment becomes a hot topic. The software radio technology put forward a feasible way to solve it. It also changes the method of designing. Direct sequence spread spectrum is a key technology in the intending communication system. It can increase the efficiency of the spectrum bandwidth utilization. This dissertation mainly studies the application of the software radio technology in the direct sequence spread spectrum (DSSS) receiver.Firstly, the concept of the software radio (SDR) and its characteristic are introduced, and the way to realize it is analyzed. And then focus on some stick point of the technology about SDR. Three kinds of structure of SDR were discussed here. We choose the mid-frequency structure as the topic in this thesis.Secondly, the method to link SDR with DSSS is discussed. The model of the DSSS receiver is built. Then, the technical indicators of the system as the design standard are proposed. The structure of the DSSS receiver is chosen to be the super heterodyne type. The software flow of the receiver is shown.Thirdly, the essential theories for the receiver design are introduced in detail. DSP is used to process the baseband signal, and it is used to design sampling filter for its flexibility and fast processing. The analog filter is replaced by digital filter after A/D conversion to improve the filter's range and the system's flexibility.Finally, the realization of de-spreading and demodulation is discussed in the software section. Meanwhile, the implement of the DSP system is introduced.Through the experiment, the result is desirable. The thesis shows the results of the graduate's research.