信号课程设计报告书---语音信号处理学院：信息工程学院专业班级：通信工程081姓名：XX学号：XXXXXX1、信号的抽样和恢复正弦波2KHz抽样输出正弦波2KHz抽样恢复正弦波8KHz抽样输出正弦波8KHz抽样恢复正弦波16KHz抽样输出正弦波16KHz抽样恢复三角波2KHz抽样输出三角波2KHz抽样恢复三角波8KHz抽样输出三角波8KHz抽样恢复三角波16KHz抽样输出三角波16KHz抽样恢复巴特沃斯低通滤波器图形低通李沙育图形巴特沃斯高通滤波器图形高通李沙育图形巴特沃斯带通滤波器图形带通李沙育图形2、对连续信号进行抽样恢复t=0:0.001:6;x=cos(5*pi*t);subplot(3,1,1);plot(t,x);axis([0,1,-1.1,1.1]);title('原有x');xlabel('t');ylabel('x(t)')fs=2;%采样频率ts=1/fs;tp=1;n=0:tp/ts;xn=cos(n*ts*0.5*pi);subplot(3,1,2)stem(n*ts,xn);title('fs=2HZ取样后的x');xlabel('t');ylabel('x(nT)')dt=ts/50;%每个采样间隔上取点数t1=0:dt:6;%生成序列t1tp=1;%重构时间区间为1sn=0:tp/ts;tmn=ones(length(n),1)*t1-n'*ts*ones(1,length(t1));xr1=sinc(fs*tmn);x2=xn*xr1;subplot(3,1,3)plot(t1,x2);axis([0,1,-1.1,1.1]);x0=cos(0.5*pi*t1);emax=max(abs(x0-x2))emax=1.9492title('用抽样内插函数恢复的结果');3、语音信号抽样恢复比较[x,fs]=wavread('xiang1.wav');subplot(2,2,1)plot(x);title('语音信号原有16k采样波形');x1=fft(x);subplot(2,2,2);plot(abs(x1));title('语音信号原有16k采样波形频谱');n=1:length(x);n2=1:0.25:length(x);yi=interp1(n,x,n2);sound('yi')subplot(2,2,3)plot(n2,yi);title('内差恢复波形');y2=fft(yi);subplot(2,2,4);plot(abs(y2));title('语音信号内差恢复波形频谱');figure(2)y2=decimate(yi,2);subplot(2,2,1)plot(y2);title('8k采样波形')y21=fft(y2);subplot(2,2,2);plot(abs(y21));title('8k采样波形频谱');sound('y21')y3=decimate(yi,4);sound('y3');subplot(2,2,3)plot(y3);title('4k采样波形');y31=fft(y3);subplot(2,2,4);plot(abs(y31));title('4k采样波形频谱');sound('y31')4、模拟及数字滤波器设计N=4;fc=22000;fs=160000;T=1/fs;wc=2*pi*fc;[B,A]=butter(N,wc,'s');[mag0,w0]=freqs(B,A);subplot(2,1,1);plot(w0/1000/2/pi,abs(mag0));title('模拟巴特沃思低通滤波器幅频特性’);xlabel('频率/KHz');ylabel('幅度');[B,A]=butter(N,wc*T,'s')[b,a]=imp_invr(B,A,1)[db,mag,pha,grd,w]=freqz_m(b,a);subplot(2,1,2);plot(w/pi,mag);title('数字巴特沃思低通滤波器幅频特性');xlabel('w/pi');ylabel('幅度');axis([0,1,0,1]);、N=4;fc=26000;fs=200000;T=1/fs;wc=2*pi*fc;[B,A]=butter(N,wc,'high','s');[mag0,w0]=freqs(B,A);subplot(2,1,1);plot(w0/1000/pi/2,abs(mag0));title('模拟巴特沃思高通滤波器幅频特性');xlabel('频率/KHz');ylabel('幅度');[b,a]=bilinear(B,A,fs);[mag1,w1]=freqz(b,a);subplot(2,1,2);plot(w1/pi,abs(mag1));title('数字巴特沃思高通滤波器幅频特性');xlabel('w/pi');axis([0,0.8,0,1]);N=4;fs=160000;T=1/fs;fc1=23000;fc2=28000;wcl=fc1*2*pi;wc2=2*pi*fc2;wc=[wcl,wc2];[B,A]=butter(N,wc,'bandpass','s');[mag0,w0]=freqs(B,A);subplot(2,1,1);plot(w0/pi/2,abs(mag0));title('模拟巴特沃思带通滤波器幅频特性');xlabel('频率/Hz');ylabel('幅度');axis([10000,40000,0,1]);[b,a]=bilinear(B,A,fs);[mag1,w1]=freqz(b,a);subplot(2,1,2);plot(w1/pi,abs(mag1));title('数字巴特沃思带通滤波器幅频特性');xlabel('w/pi');ylabel('幅度');axis([0.1,0.5,0,1]);5、语音加噪声及滤波后比较[x,fs]=wavread('ai30');N=length(x);n=0:length(x)-1;c=2*pi*n/N;y=fft(x,length(x));subplot(2,2,1);plot(x);title('语音信号时域波形');subplot(2,2,2);plot(c,abs(y));title('语音信号幅频特性');x1=0.008*cos(0.75*2*pi*n);y1=x'+x1;y2=fft(y1);subplot(2,2,3);plot(y1);title('加噪音后的波形');subplot(2,2,4);plot(abs(y2));title('加噪音后的频谱');figure(2)[n,m]=butter(4,0.5,'low');[db,mag,pha,w]=freqz_m(n,m);subplot(2,...
