數(shù)字信號(hào)處理實(shí)驗(yàn)四

學(xué)生姓名：強(qiáng)亞倩指導(dǎo)教師：范杰清華北電力大學(xué)(北京)一、實(shí)驗(yàn)?zāi)康纳羁汤斫怆x散時(shí)間系統(tǒng)的系統(tǒng)函數(shù)在分析離散系統(tǒng)的時(shí)域特二、實(shí)驗(yàn)原理MATLAB提供了許多可用于分析線性時(shí)不變連續(xù)系統(tǒng)的函數(shù)，主H(z)=Y(z)==b(z)點(diǎn)分析注意：在利用這些函數(shù)時(shí)，要求H(z)的分子多項(xiàng)式和分母多項(xiàng)z=ejH(ej)=H(z)=H(ej)ej()z=ej 通過(guò)測(cè)量系統(tǒng)在已知輸入x[k]激勵(lì)下的響應(yīng)y[k]來(lái)確定系統(tǒng)的特為Y(ej)，則系統(tǒng)的頻率特性可表示為：H(ej)=Y(ej)X(ej)Xfftx,N);Y=fft(y,N);HYXhifft(H,N) y1,y[2]=2，輸入x[k]=u[k]計(jì)算系統(tǒng)的(2)當(dāng)以下三個(gè)信號(hào)分別通過(guò)系統(tǒng)時(shí)，分別計(jì)算離散系統(tǒng)的零狀態(tài)響應(yīng)：x[k]=cos(k)u[k];x[k]=cos(k)u[k];x[k]=cos(7k)u[k]11025310(3)該系統(tǒng)具有什么特性？N0;b675,0.1349,0.0675];a.412];baxziN;b675,0.1349,0.0675];a.412];ziy=Columns1through60.38650.23220.37600.60410.80540.9416Columns7through121.01431.04131.04221.03221.02021.0108Columns13through181.00491.00201.00121.00151.00211.0027Columns19through241.00311.00331.00341.00351.00341.0034Columns25through301.00341.00341.00331.00331.00331.003Columns31through361.00331.00331.00331.00331.00331.0033Columns37through421.00331.00331.00331.00331.00331.0033Columns43through481.00331.00331.00331.00331.00331.0033Columns49through541.00331.00331.00331.00331.00331.0033Columns55through601.00331.00331.00331.00331.00331.0033Columns61through661.00331.00331.00331.00331.00331.0033Columns67through721.00331.00331.00331.00331.00331.0033Columns73through781.00331.00331.00331.00331.00331.0033Columns79through841.00331.00331.00331.00331.00331.0033Columns85through901.00331.00331.00331.00331.00331.0033Columns91through961.00331.00331.00331.00331.00331.0033Columns97through1001.00331.00331.00331.0033y=yy=y(1)計(jì)算系統(tǒng)的單位脈沖響應(yīng)。(2)當(dāng)信號(hào)x[k]=u[k]+cos(k)u[k]+cos(k)u[k]42y=yColumns1through60.03570.21550.58630.97371.14921.1002Columns7through120.99030.94720.9735Columnsrough0.99510.99400.9989Columnsrough0.99930.9996ColumnsroughColumnsroughColumnsroughColumnsroughColumnsroughColumnsroughColumnsroughColumnsroughColumnsrough1.00021.00021.0002Columns79through841.00021.00021.0002Columns85through901.00021.00021.0002Columns91through961.00021.00021.0002Columns97through1001.00021.00021.00021.0002111(a)x[k]=()ku[k],y[k]=()ku[k]+()ku1112424444(1)利用系統(tǒng)辨識(shí)原理從頻域分別求解系統(tǒng)的單位脈沖響(2)利用解析方法確定H(ej)，并求出系統(tǒng)的單位脈沖響 X1=fft(x1);Y1=fft(y1);H1=ifft(H1)4666，-55.2433，70.7979，-87.7810(1)繪出輸入輸出信號(hào)的波形。(2)計(jì)算該系統(tǒng)的頻率響應(yīng)H(ej)，并繪出其幅頻特性。(3)計(jì)算該系統(tǒng)的單位脈沖響應(yīng)h[k]，并繪出其波形。(1)x=[2,0.8333,0.3611,0.162,0.0748,0.0354,0.017,0.0083,0.0041,0.002,0.001,0.0005,0.0002,0.0001,0.0001];y=[0.0056,-0.0259,0.073,-0.1593,0.297,-0.4974,0.7711,-1.1267,1.5702,-2.1037,2.724,-3.4207,4.174,-4.9528,5.7117,-6.3889,6.9034,-7.1528,7.012,-6.3322,4.9416,-2.648,-0.7564,5.4872,-11.7557,19.7533,-29.6298,4(2)x=[2,0.8333,0.3611,0.162,0.0748,0.0354,0.017,0.0083,0.0041,0.002,0.001,0.0005,0.0002,0.0001,0.0001];y=[0.0056,-0.0259,0.073,-0.1593,0.297,-0.4974,0.7711,-1.1267,1.5702,-2.1037,2.724,-3.4207,4.174,-4.9528,5.7117,-6.3889,6.9034,-7.1528,7.012,-6.3322,4.9416,-2.648,-0.7564,5.4872,-11.7557,19.7533,-29.6298,41.4666,-55.2433,70.7979,-87.7810];(3)h=ifft(H);plot(h0);(1)下列數(shù)字濾波器能夠?yàn)V除信號(hào)y[k]中500Hz正弦型干擾器的幅頻特性和相頻特性，比較零極點(diǎn)分布與濾波器頻率特性的關(guān)(2)利用該數(shù)字濾波器濾除信號(hào)中的噪聲，利用FFT觀察其頻(1)a=[1,-3.594,5.17,-3.494,0.945];b=[0.6877,-2.509,3.664,-2.509,0.6877];z=roots(b);p=roots(a);subplot(2,2,1);zplane(b,a);[H,w]=freqz(b,a);subplot(2,2,2);plot(w,abs(H));xlabel('w(rad)');ylabel('H0');title('·ù?μì?D?');subplot(2,2,3);plot(w,angle(H));xlabel('w(rad)');ylabel('');title('?à?μì?D?');(2)loadmtlbN=150;x=mtlb(1:N);k=1:N;subplot(2,3,4);plot(k,x);title('′|àí?°');X=fft(x,150);h=ifft(H);H=fft(H,150);Y=X.*H;y=ifft(Y);subplot(2,3,5);plot((1:N),y);title('′|àíoó');(2)loadmtlbN=150;x=mtlb(1:N);k=1:N;subplot(2,3,4);plot(k,x);title('′|àí?°');X=fft(x,150);h=ifft