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1、Section:threeLaboratoryExercise3DISCRETE-TIMESIGNALS:FREQUENCY-DOMAINREPRESENTATIONS3.1DISCRETE-TIMEFOURIERTRANSFORMProject3.1DTFTComputationAcopyofProgramP3_1isgivenbelow:w=-4*pi:8*pi/511:4*pi;num=[21];den=[1-0.6];h=freqz(num,den,w);%PlotDFDTsubplot(2,1,1)plot(w/pi,real
2、(h));gridtitle('H(e^{jomega})的实部')xlabel('omega/pi');ylabel('振幅');subplot(2,1,2)plot(w/pi,imag(h));gridtitle('H(e^{jomega})的虚部')xlabel('omega/pi');ylabel('振幅');pausesubplot(2,1,1)plot(w/pi,abs(h));gridtitle('H(e^{jomega})幅度谱')xlabel('omega/pi');ylabel('振幅');subp
3、lot(2,1,2)plot(w/pi,angle(h));gridtitle('H(e^{jomega})相位谱')xlabel('omega/pi');ylabel('以弧度为单位的相位');Q3.1TheexpressionoftheDTFTbeingevaluatedinProgramP3_1is-Thefunctionofthepausecommandis–用于暂停matlab程序，用户按任意键继续。若pause含参数n，则n秒后继续执行。Q3.2TheplotsgeneratedbyrunningProgramP3_1
4、areshownbelow:按下任意键后：>TheDTFTisa______周期___functionofw.Itsperiodis-2*piThetypesofsymmetriesexhibitedbythefourplotsareasfollows:1、实部图是2pi为周期的偶对称2、虚部图是2pi为周期的奇对称3、幅度谱是2pi为周期的偶对称4、相位谱是2pi为周期的奇对称Q3.3TherequiredmodificationstoProgramP3_1toevaluatethegivenDTFTofQ3.3aregivenbel
5、ow:N=512;num=[0.7-0.50.31];den=[10.3-0.50.7];[h,w]=freqz(num,den,N);%PlotDFDTsubplot(2,1,1)plot(w/pi,real(h));gridtitle('H(e^{jomega})的实部')xlabel('omega/pi');ylabel('振幅');subplot(2,1,2)plot(w/pi,imag(h));gridtitle('H(e^{jomega})的虚部')xlabel('omega/pi');ylabel('振幅');
6、pausesubplot(2,1,1)plot(w/pi,abs(h));gridtitle('H(e^{jomega})幅度谱')xlabel('omega/pi');ylabel('振幅');subplot(2,1,2)plot(w/pi,angle(h));gridtitle('H(e^{jomega})相位谱')xlabel('omega/pi');ylabel('以弧度为单位的相位');>TheplotsgeneratedbyrunningthemodifiedProgramP3_1areshownbelow:<>
7、TheDTFTisa_____周期____functionofw.Itsperiodis-2*piThejumpinthephasespectrumiscausedby-要计算一个系统相频特性，就要用到反正切函数，计算机中反正切函数规定，在一、二象限中的角度为0～pi，三四象限的角度为0～-pi。若一个角度从0变到2pi，但实际得到的结果是0～pi，再由-pi～0，在w=pi处发生跳变，跳变幅度为2pi，这就叫相位的卷绕。Thephasespectrumevaluatedwiththejumpremovedbythecommandunw
8、rapisasgivenbelow:<>Q3.4TherequiredmodificationstoProgramP3_1toevaluatethegivenDTFTofQ3.4aregivenbelow:
