语音信号处理及数字滤波器设计报告.docx
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语音信号处理及数字滤波器设计报告
Forpersonaluseonlyinstudyandresearch;notforcommercialuse
Forpersonaluseonlyinstudyandresearch;notforcommercialuse
信号课程设计报告书
Forpersonaluseonlyinstudyandresearch;notforcommercialuse
---语音信号处理
Forpersonaluseonlyinstudyandresearch;notforcommercialuse
学院:
信息工程学院
专业班级:
通信工程081
姓名:
XX
学号:
XXXXXX
1、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t1
tp=1;%重构时间区间为1s
n=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=1.9492
title('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(2,2,1);plot(w,mag);title('滤波器的幅度特性');
subplot(2,2,2);plot(w,pha);title('滤波器的相频特性');
T=200000;wc1=1;N=4;
[B,A]=butter(N,wc1,'s');[Bz,Az]=impinvar(B,A);
z=filter(Bz,Az,y1);
z1=fft(z);
subplot(2,2,3);plot(z);title('加噪音滤波后的波形');
subplot(2,2,4);plot(abs(z1));title('加噪音滤波后的频谱');
6、三个频率信号叠加及滤波实现
t=0:
1000;x=cos(0.3*pi*t)+2*sin(0.6*pi*t)+cos(0.8*pi*t);X=fft(x);
figure
(1)
subplot(2,2,1);plot(t,x);title('连续信号时域波形');axis([0,60,-4,4]);
subplot(2,2,2);plot(abs(X));title('连续信号频谱图');
figure
(2)
wp1=0.35;ws1=0.4;As=20;Rp=1;
[N1,wc1]=buttord(wp1,ws1,Rp,As);[b1,a1]=butter(N1,wc1);
[mag1,w1]=freqz(b1,a1);
subplot(3,1,1);plot(w1/pi,abs(mag1));title('数字巴特沃思低通滤波器幅度特性');
wp2=[0.5,0.65];ws2=[0.45,0.75];
[N2,wc2]=buttord(wp2,ws2,Rp,As);[b2,a2]=butter(N2,wc2,'bandpass');
[mag2,w2]=freqz(b2,a2);
subplot(3,1,2);plot(w2/pi,abs(mag2));title('数字巴特沃思带通滤波器幅度特性');
wp3=0.7;ws3=0.65;
[N3,wc3]=buttord(wp3,ws3,Rp,As);[b3,a3]=butter(N3,wc3,'high');
[mag3,w3]=freqz(b3,a3);
subplot(3,1,3);plot(w3/pi,abs(mag3));title('数字巴特沃思高通滤波器幅度特性');
figure(3)
y1=filter(b1,a1,x);Y1=fft(y1);
subplot(3,2,1);plot(t,y1);title('低通滤波器滤波后时域波形');axis([0,60,-1,1]);
subplot(3,2,2);plot(abs(Y1));title('低通滤波器滤波后频谱图');
y2=filter(b2,a2,x);Y2=fft(y2);
subplot(3,2,3);plot(t,y2);title('带通滤波器滤波后时域波形');axis([0,60,-2,2]);
subplot(3,2,4);plot(abs(Y2));title('带通滤波器滤波后频谱图');
y3=filter(b3,a3,x);Y3=fft(y3);
subplot(3,2,5);plot(t,y3);axis([0,30,-1,1]);title('高通滤波器滤波后时域波形');
subplot(3,2,6);plot(abs(