【正文】 由于在電路實(shí)現(xiàn)時(shí)必須將數(shù)字信號看作離散時(shí)間信號,為方便起見，我們。但是，在采用很少的位數(shù)，比如4位或者8位的專用硬件中，量化誤差的研究是很重要的。量化時(shí),如果離散信號的幅度與量化電平不一致,那么就必須采用截?cái)嗷蛩纳嵛迦氲姆绞綄⑺炕癁槟硞€(gè)量化電平,在這兩種情況下,都會(huì)出現(xiàn)誤差，這種誤差被稱為量化誤差。然而,離散時(shí)間信號的研究就沒有這個(gè)問題。假設(shè)每個(gè)數(shù)值都四舍五入為最近的整數(shù)(即量化階為1)，則有　　這里Q表量化。然而，對于數(shù)字信號的分析研究是很困難的,因?yàn)榱炕皇蔷€性過程。在實(shí)際常見的信號大多是連續(xù)時(shí)間信號，要以數(shù)字化方式處理模擬信號,應(yīng)先對模擬信號在時(shí)間上離散化以產(chǎn)生離散時(shí)間信號，然后對其幅值量化以產(chǎn)生數(shù)字信號。例如,我們有　　1 1 0 0 1 1 ←→(1+0+0+1*+1*)=　　0 0 1 1 1 0←→0*+1*+1*+1*+0*=除符號位外最左邊的位是最高有限位,而最右邊的位是最低有效位。考慮以下序列，　　 符號位 每一稱為一個(gè)二進(jìn)制位或比特，取值只能是1或0。二進(jìn)制數(shù)編碼的方式有很多種。這種類型的表示受噪聲的影響較少,而且很容易實(shí)現(xiàn)。凹痕的前端和后端代表1。在此情況下，可以發(fā)送錯(cuò)誤信息，重傳信號。每個(gè)符號表示的精確電壓值并不重要,關(guān)鍵是它的值是否在上述任意一個(gè)允許的范圍內(nèi)。不過，由于這種表示法容易受噪聲、電源起伏及其他干擾的影響而未被采用。這些消息由26個(gè)英文字母組成，10個(gè)數(shù)字，逗號，句號等符號組成。 sonar, where national security was at risk；irreplaceable。 they can always be exactly reproduced.The storage of digital signals is easier than that of analog signals. Digital signals can be easily stored in shift registers, memory chips, floppy disks, or pact discs for an long an needed without loss of accuracy. These data can be retrieved for use in a few microseconds. This easy storage and rapid access is an important feature of digital techniques, the only convenient way to store analog signals is to tape or film them. Their retrieval is not an convenient and fast an in digital techniques.Digital techniques are more flexible and versatile than analog techniques. In digital display, digital signals can easily be frozen, expanded, or manipulated. A digital system can be easily ponents. Using time multiplexing, a digital syetem can be used to process a number of digital signals: for example, if the sampling period of a digital signal is and if the processing of the signal requires only , then the digital system will be free in the next and can be used to process other signals. Another example of this type of arrangement is the digital transmission of human voices. On a telephone line, the voice is sampled 8000 times per second。then we have where Q stands for quantization. Because of there nonlinear phenomena, analytical study of digital signals is plicated. There are, however no such problems in studying discretetime signals. In actual processing or implementation, all discretetime signals must be converted into digital signals. In quantization, if the amplitude of discretetime signal does not fall exactly on a quantization level, then the value must be approximated by a quantization level either by truncation or rounding, in either case, errors will occur. Such errors are called quantization errors.In general, quantization errors are studied separately in digital signal processing. Such a study is important in specialized hardware that uses a small number of bits such as 4 or 8 bits. On digital puters and DSP processors that have 16 or 32 bits, quantization errors are very small and can often be simply ignored. For convenience, we use digital signals and discretetime signals interchangeably with the understanding that all DT signals must be transformed into digital signals in implementation and al digital signals are considered an DT signals in analysis and design.Comparison of Digital and Analog TechniquesDigital techniques have bee increasingly popular and have replaces, in many applications, analog techniques. We discuss some of the reasons in the following.Digital techniques are less susceptible to noise and disturbance. In the transmission and processing of analog signals, any noise or disturbance will affect the signals. Digital signals are coded in 1s and 0s, which are represented by ranges of voltages。附錄1：外文文獻(xiàn)和翻譯外文原文 Introduction to Digital Signal ProcessingRepresentation of Digital SignalsMessages sent by telegraph are digital signals. They are written using 26 alphabetical characters, 10 numerals, are symbols such as mas and periods. These symbols certainly can be represented by different voltage levels, for example, A by 10V(volts), B by , C by 9V,and so forth. This type of representation , however, is not used because it is susceptible to noise, shifting of power supply, and any other disturbances. In practice, there symbols are coded sequences of dashes and dots or, equivalently, ones and zeros. The symbol 0 can be represented by a voltage from 0 to . the symbol 1 can be represented by voltage from to . The precise voltage of each symbol is not important, but it is critical that its value lies within one of the two allowable ranges. If the value lies outside the two allowable ranges, the telegraph must make a choice of either 1 or 0, On the pact disc, 1 and 0 are represented by dimples. The leading and trailing edges of dimple represent a 1。其次要感謝的是同一組導(dǎo)師的各位同學(xué)，每個(gè)人對我的設(shè)計(jì)都有或多或少的啟發(fā)和幫助，他們教會(huì)我怎樣使用MATLAB的界面設(shè)計(jì)，使我的設(shè)計(jì)有了突破性的進(jìn)展。 參考文獻(xiàn)[1] 陳后金、薛鍵、胡健.《數(shù)字信號處理》，高等教育出版社，2004 [2] 薛年喜.《MATLAB在數(shù)字信號處理中的應(yīng)用》，清華大學(xué)出版社，2008[3] 沈捷、實(shí)驗(yàn)技術(shù)與管理，2008（2），25卷第2期[4]沈捷、電腦開發(fā)與應(yīng)用，2009,20卷第九期[5]陳亮、郝衛(wèi)東、喬建華，基于MATLAB的濾波器分析界面設(shè)計(jì)，現(xiàn)代電子技術(shù)，2009，第10期[6]劉舒帆、陸輝、費(fèi)諾，信號處理類實(shí)驗(yàn)課的階梯式教學(xué)研究，電子高等教育學(xué)會(huì)2005年學(xué)術(shù)年會(huì)論文集，2005[7]吳永深，基于VB與MATLAB的數(shù)學(xué)與數(shù)字信號處理實(shí)驗(yàn)系統(tǒng)的設(shè)計(jì)與實(shí)現(xiàn)，東莞理工學(xué)院學(xué)報(bào)，2006，第13卷第3期[8]肖江、張鴻存、費(fèi)諾、劉舒帆，數(shù)字信號處理實(shí)驗(yàn)系統(tǒng)的結(jié)果與應(yīng)用，實(shí)驗(yàn)室研究與探索，2001，第20卷第4期[9]李顯宏，《》，電子工業(yè)出版社，2006[10]周明、李長虹、雷虎明，《MATLAB圖形技術(shù)》，西北工業(yè)大學(xué)出版社，1999[11]韓芝俠、王強(qiáng)、脫慧，基于MATLAB GUI 的數(shù)字濾波器設(shè)計(jì)與實(shí)現(xiàn)，陜西理工學(xué)院學(xué)報(bào)，2007，第23卷第1期致謝經(jīng)過了兩個(gè)多月的努力，在老師的精心指導(dǎo)下，終于完成了最終的畢業(yè)設(shè)計(jì)。本文將MATLAB作為二次開發(fā)平臺，結(jié)合理論教學(xué)的的內(nèi)容，利用圖形用戶界面的形式，開發(fā)該課程的教學(xué)實(shí)驗(yàn)系統(tǒng)，并對實(shí)驗(yàn)內(nèi)容所包括的主要功能進(jìn)行了詳細(xì)的說明。數(shù)字信號處理課程理論性教強(qiáng)，大多抽象難懂，如何幫助學(xué)生理解和掌握課程中的基本概念、基本原理、基本分析方法是該課程教學(xué)中所要解決的關(guān)鍵問題。大多數(shù)實(shí)驗(yàn)都是驗(yàn)證性實(shí)驗(yàn)，GUI界面操作起來有點(diǎn)煩雜，還需要改進(jìn)。（4）教學(xué)實(shí)驗(yàn)系統(tǒng)的設(shè)計(jì)：這一步中，要將選取的實(shí)驗(yàn)整合在一個(gè)系統(tǒng)中，借助的工具是MATLAB，通過GUI界面的設(shè)計(jì)，使各個(gè)實(shí)驗(yàn)的內(nèi)容和結(jié)果直觀可視，方便教學(xué)和學(xué)生自學(xué)。（2）資料查找：本次設(shè)計(jì)需要找數(shù)字信號處理的實(shí)驗(yàn)和MATLAB的使用步驟，特別是界面設(shè)計(jì)的知識。第6章 總結(jié)本次畢業(yè)設(shè)計(jì)，我選的課題以數(shù)字信號處理為基礎(chǔ)，結(jié)合MATLAB設(shè)計(jì)實(shí)驗(yàn)的圖形用戶界面，經(jīng)過了任務(wù)分析、資料查找、相關(guān)理論知識的學(xué)習(xí)和教學(xué)實(shí)驗(yàn)系統(tǒng)的設(shè)計(jì)等階段。點(diǎn)擊“實(shí)驗(yàn)結(jié)果”控件。等波紋FIR濾波器是指用Chebyshev誤差準(zhǔn)則設(shè)計(jì)出的FIR濾波器的幅度響應(yīng)在通帶和阻帶都會(huì)呈現(xiàn)等波波紋的波動(dòng)。點(diǎn)擊“實(shí)驗(yàn)內(nèi)容”控件。程序見（附錄2）。 實(shí)驗(yàn)內(nèi)容 本實(shí)驗(yàn)要求設(shè)計(jì)出多帶的FIR濾波器，并與期望的幅頻響應(yīng)的結(jié)果進(jìn)行比較。程序見（附錄2）。 實(shí)驗(yàn)內(nèi)容本實(shí)驗(yàn)要求實(shí)現(xiàn)系統(tǒng)的格型結(jié)構(gòu)。點(diǎn)擊“實(shí)驗(yàn)結(jié)果”控件，出現(xiàn)結(jié)