【作者】 李文亮；

【导师】 姚冬苹；

【作者基本信息】 北京交通大学 ， 通信与信息系统， 2008， 硕士

【摘要】 “软件无线电-SDR”是第三代移动通信系统(3G)的关键技术之一。数字下变频技术和同步技术一直是软件无线电研究的重点,也是影响软件无线电性能最大的部分。在整个软件无线电系统的设计过程中需要耗费很多的资源和精力。本文重点研究了数字接收机中的数字下变频(DDC)技术。在基于中频采样的条件下,对信号采样理论、数字正交混频理论、多采样率数字信号处理、高效数字滤波器进行探讨。并在此基础上设计和搭建了一个有实用价值的数字接收机平台。该平台基于数字下变频技术,主要由功率放大器、抗混叠滤波器、A/D转换器、下变频处理器、FPGA和DSP等部分组成。本文对该接收机的组成及各部分功能进行了介绍,对其中的数字下变频器HSP50214B作了深入的研究。然后以数字音频广播(DAB)系统为参考,结合接收机平台的信号处理能力,设计了一套适用于本系统的下变频参数,并通过仿真进行了理论验证。在此基础上,通过软件编程和硬件电路调试,实现了OFDM信号的下变频处理。之后对该平台的通用性进行了研究,并通过AM信号和ASK信号的下变频处理进行了实际验证。论文最后给出了系统调试的结果,并对部分结论进行了分析。更多还原

【Abstract】 "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.更多还原