摘要
DSP技术一般指将DSP处理器用于完成数字信号处理的方法与技术。目前的DSP芯片以其强大的数据处理功能在通信和其他信号处理领域得到广泛注意，并已成为开发应用的热点技术。美国德州仪器（TI）开发的DSP处理器芯片占据目前DSP市场50％以上的份额，许多领域对于数字信号处理器的应用都是围绕美国德州仪器所开发的DSP处理器来进行的。
DSP芯片是一种特别适合于进行数字信号处理运算的微处理器，其主要应用是实时快速的实现各种数字信号处理算法，如卷积、相关以及各种变换等。
其中，利用DSP来实现数字滤波器就是很重要的一种应用。
本文深入研究基于美国德州仪器公司(TI)TMS320C5402 DSP芯片的滤波器系统软件实现方法，并实现了能独立完成语音降噪的硬件系统。算法系统由C及汇编语言编写，并通过RCP或CMD文件对内存分配，最终写入片内实现预期功能。完成的主要工作如下：
1.窗口设计法实现FIR滤波器。此设计法实现的滤波器，可通过调用四种窗口函数，截取不同的滤波原型，以满足不同的性能要求。
2.用时间抽取法实现的FFT/IFFT算法。通过此算法，可以对信号进行频域分析、频域处理，在通讯工程领域有着重要的应用。
3.三段均衡器的设计实现。本均衡器通过对各频点信号幅值的控制，达到对信号频谱控制的目的。
4自适应滤波器，目前数字滤波器领域中最为活跃的分支。采用经过改进的LMS（最小均方误差）算法来实现自适应滤波器，它以均方误差最小为准则，能自动调节单位的最小脉冲响应，以达到最优滤波效果，这种方法简便易行，已经被广泛采用。讨论如何通过改进的LMS算法，利用DSK上的资源对混入噪音的语音信号进行实时处理以得到纯净的语音信号的。
5 语音降噪的硬件系统：以TMS320C5402芯片为核心、包括模数、数模转换电路，外存储器和逻辑控制电路在内的硬件电路，实现了语音降噪。
本论文共分为五部分。第一章为绪论部分介绍DSP及滤波器的发展现状，第二章详细介绍DSP的特点、性能指标、软件开发工具、指令系统及硬件结构，第三章介绍FIR滤波器的窗口设计法实现及其简单应用，第四章介绍自适应滤波的实现及其应用，三、四章是本论文的核心部分，最后一部分给出结论以及本工作的改进方向。
DSP technology means the technology to accomplish digital signal processing. Nowadays DSPs are getting more and more attentions in the information field, due to its powerful signal processing ability, becoming a hot-point technique in communication and other relating signal processing areas. DSP chips produced by TI(Texas Instrument ) hold 50 percent in whole DSP market, many applications of digital signal processing are carried out around TI DSP.
DSP chip is especially fit for digital signal processing, its main application is realizing all kinds of digital siginal processing arithmetics such as clove hitch、 correlation 、all kinds of transforms etc. Realizing digital filters with DSP is an important application.
The paper discusses the filter's software realization based on TMS320C5402, and finished the hardware system of noise-restraining. The arithmetic system was compiled with C and assemble language, distributing memory with RCP or CMD files , writing into chip and realizing expectable functions. The main works accomplished are as following:
1 realizing FIR filter with window function. The filter can satisfied different characteristics requirements by transferring four window functions, intercepting different filter archetypes.
2 realizing FFT/IFFT with time-drawing. we can make frequency domain analysis and disposal with it. The arithmetic has important application in communication engineering.
3 realization of three-segment equalizer. we can control spectrum through control to the signal amplitude.
4 Self-adaptive filter, the most active one in digital filters. The improved LMS arithmetic can adaptive the minimum pulse response automatically by the guide line of minimum average square error and have the best filtering effect. The method is easy to practise and has been introduced extensively. We can process real time disposal to the voice signal with noise and get pure voice signal.
5 noise restraining hardware system: the system's core is TMS320C5402 chip, including A/D、D/A、ROM and Logical circuit, it has realized noise restraining.
There are five parts in this paper. The first chapter introduces the developing statement of DSP and filters. The second one discusses DSP's characteristics、 performance index、 development tools of software、 repertoire and hardware structure. The third part in this paper describes FIR filter's window function method and its application. The fourth introduces self-adaptive filter's realization and its
application. The kernel of this paper locates in the third and fourth chapters. The last part of this paper draws the conclusion and conceives this task's betterments.
引文
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