lixiangdaitonglvboqidebijin.m

理想带通滤波器的逼近,在某种程度上可以代替理想带通滤波器.

%带通滤拨( 逼近理想带通)
fs=8000;
wp=[400,3200]/(fs/2);
ws=[350,3250]/(fs/2);
rp=0.001;
rs=30;
 [n,wn]=cheb1ord(wp,ws,rp,rs);
[b,a]=cheby1(n,rp,wn);
[h,w]=freqz(b,a);
plot(w*fs/(2*pi),abs(h))

%的 到短时 能 ;量, 加 窗,FFT


input_filename='e:\B012_Ori.wav';
>> N=240;
>> Y=wavread(input_filename,[1 18000]);
>> L=length(Y);
>> LL=length(Y)/N;
>> Em=zeros(1,(LL-1)*240);
>> for ii=1:(LL-1)*240
temp=Y(ii:ii+240-1);
temp=temp.*hamming(240);
Em(ii)=sum(temp.*temp);
end
plot(jj,Em);
jj=[1:(LL-1)*240];
subplot(4,1,1);
YY=fft(Em,256);
>> f=500*(0:128)/256;
>> plot(f,YY(1:129));


% 汉明窗的短时的付立叶变换
input_filename='e:\B012_Ori.wav';
offset=17700;
N=400;
fid=fopen(input_filename,'r');
fseek(fid,offset*2,-1);
[y,count]=fread(fid,N,'int16');
fclose(fid);
y=y.*hamming(N);
%画出时域波形图
figure(1);
subplot(2,1,1);
x=0:N-1;
plot(x,y)
%画出频谱图
figure(2);
FFTSIZE=8000;
Y=zeros(FFTSIZE,1);
Y=20*log10(abs(fft(y,FFTSIZE)));
plot(Y(1:4000));