基于FPGA的数字下变频器的设计与应用

【作者】 刘力；

【导师】 李广军； 任小军；

【作者基本信息】 电子科技大学 ， 电子与信息工程， 2006， 硕士

【摘要】 软件无线电的中心思想是构造一个具有开放性、标准化和模块化的通用硬件平台，将宽带A／D和D／A转换器尽可能靠近天线，用软件完成各种通信功能，以研制出高度灵活性和适应性的无线通信系统。A／D变换器制造技术的进步，其工作带宽覆盖到中频频段，并具有较高的采样频率和足够大的动态范围，从而使无线电接收机技术由基带数字化向中频数字化方向发展，因此，实现基于带通采样定理的宽带数字中频软件无线电接收机成为可能。本文设计和实现了基于FPGA的数字下变频器DDC，用于宽带数字中频软件无线电接收机中。采用自上向下的模块化设计方法，将DDC的功能划分为基本单元，实现这些功能模块并组成模块库。在具体应用时，优化配置各个模块来满足具体无线通信系统性能的要求。这样做比传统ASIC数字下变频器具有更好的可编程性和灵活性，从而满足不同的工程设计需求。本文章首先阐述了软件无线电中关键的数字信号处理技术，包括中频处理中的下变频技术、抽取技术以及带通采样技术。利用MATLAB的Simulink完成了对系统的设计与仿真，验证了设计的正确性。之后用QuartusⅡ进行了基于FPGA抽取滤波器和NCO等关键模块的设计，编译后进行了时序仿真，最后在PCB板上实现了实际电路并应用于工程项目中。更多还原

【Abstract】 The foundamental idea of Software Defined Radio(SDR) is to establish a open,standard and modular universal hardware platform where the A/D converter is moved asclosed as possible to antenna and all of the communication function is realized bysoftware. The aim is to research and develop a high flexible and adaptablecommunication system. The technology of making A/D converter has been advancedfast. The A/D working bandwidth has covered the intermediate frequency (IF)supporting high sampling frequency and wide dynamic range and long length. Thewireless receiver technology has been developing from digital baseband to digital IF.Thusit is possible to implement the wide bandwidth digital IF receiver based onbandpass sampling theory.In this paper, a digital down converter (DDC) applied on wide bandwidth digital IFreceiver is design and implemented by FPGA. This DDC can translate digital IF signalto baseband, extract desired channel, decimate the sample sequence, multirate converterand channel shape. Using Top-Down design method, the whole DDC function is dividedto many units implemented respectively and organized to the module library. Whenapplying DDC on receiver, these function modules are selected, configured andoptimized to a complex module a designed to satisfy the wireless system demand. ThisDDC based module library and re-conftgurable structure are more flexible andprogrammable than classic ASIC down converter.This dissertation introduced the concept and the structure of Software DefinedRadio, as well as an specific application of FPGA for Software Radio.According to therequirement of system, system design and simulation was processed with MATLABSimulink, which verified the vaIidity of design. Then the design of some keymodules(interpolation and decimation filters, NCO, etc.) which were based on FPGAwas carried into execution with QuartusⅡ, and the simulation was implemented aftercomplitatioin. At last circuit was realized on PCB and applied to our project.更多还原