Research And Implementation Of SDR Receiver Based On Digital Frequency Conversion

"Soft-Defined Radio-SDR" is the most important part in the 3G Mobile Communication System. As the key technology of SDR, DDC has been a hot research topic in this field, moreover, it plays a major role in the performance of SDR and itneeds a lot of resources and energies in the whole design process of SDR system.This paper puts emphasis upon the DDC technology of Digital Receiver. Itanalyzes and researches signal sampling theorem, digital signal orthogonal mixing theorem, multi-sample rate signal processing and high speed digital filter based on IF sampling. And it also designs a practical DDC platform after considering these classic theories.This platform is based on Digital Frequency Conversion technology, it consists of PA, Resist-mixing Filter, ADC, DDC, FPGA, DSP and so on. This paper introduces these crucial modules and their functions, especially does deep research in the DDC processor HSP50214B.And then, referenced in DAB system and taking the signal processing ability of the receiver platform into consideration, we design the suitable down frequency conversion parameters of this platform, and validate it theoretically by simulation. Based on these, we implemented the down frequency conversion processing of OFDM signals by software programming and hardware circuit debugging. Then we researched the flexibility of the platform and validate it practically using AM signal. Finally, the results after system debugging are given, and the analysis of part of the conclusions are also included.