frequency response of discrete time signal
DESCRIPTION
Frequency Response of Discrete Time SignalTRANSCRIPT
Time – Frequency Response of a Discrete-time Signal
uiopen('C:\Users\Sean\Downloads\EC41FA1_ECE401_Veeneebeni_Experiment5\Chipmunks_sound-Uday-1052330468.wav',1)[x,Fs,nbits]=wavread('C:\Users\Sean\Downloads\EC41FA1_ECE401_Veeneebeni_Experiment5\Chipmunks_sound-Uday-1052330468.wav');t=0:1/Fs:(length(x)-1)/Fs;subplot(211);plot(t,x);subplot(212);specgram(x,512,Fs,hamming(256),128);title('Figure 1. Spectrogram plot of waveform chipmunks sound')
Frequency Response of a Two – Dimensional Signal
img = imread('lena_gray','tiff');X =fftshift(img(:,:,2));X1=fft2(X);Xabs=abs(fftshift(X1));Xlog=100*log(1+Xabs); subplot(221);colormap(gray);imagesc(img);title('Original Image')axis off; subplot(222);colormap(gray);imagesc(Xlog);title('Corresponding Spectrum')axis off; subplot(223);colormap(gray(256));imagesc(angle(X1));title('Magnitude Spectrum')axis off
Two-Dimension Lowpass Filter
h=[-1 -1 -1; -1 8 -1; -1 -1 -1];H=fft2(h,512,512);Hlog=log(1+abs(H));u=-256:255;v=-256:255;[u,v]=meshgrid(u,v);subplot(221);imagesc([Hlog(257:512,257:512),Hlog(257:512,256)]);axis offsubplot(222);mesh(u,v,[Hlog(257:512,257:512),Hlog(257:512,1:256);Hlog(1:256,257:512) Hlog(1:256,1:256)]);
Magnitude spectrum of low pass filter
Laboratory Exercises
1.
%Fs=8000Hz Resolution= 512n=[0:31];x=[ones(1,4) zeros(1,4) ones(1,4) zeros(1,4) ones(1,4) zeros(1,4) ones(1,4) zeros(1,4)];stem(n,x);title('Square Wave sequence, n= 0.....31');figureFs=8000;freqz(n,x,512,Fs);figure
Fs=8000Hz Resolution= 512%Fs=16000Hz Resolution= 512n=[0:31];x=[ones(1,4) zeros(1,4) ones(1,4) zeros(1,4) ones(1,4) zeros(1,4) ones(1,4) zeros(1,4)];stem(n,x);title('Square Wave sequence, n= 0.....31');figureFs=16000;freqz(n,x,512,Fs);figure
Fs=16000Hz Resolution= 512%Fs=8000Hz Resolution= 1024n=[0:31];x=[ones(1,4) zeros(1,4) ones(1,4) zeros(1,4) ones(1,4) zeros(1,4) ones(1,4) zeros(1,4)];stem(n,x);title('Square Wave sequence, n= 0.....31');figureFs=8000;freqz(n,x,1024,Fs);figure
Fs=8000Hz Resolution= 1024%Fs=16000Hz Resolution= 1024n=[0:31];x=[ones(1,4) zeros(1,4) ones(1,4) zeros(1,4) ones(1,4) zeros(1,4) ones(1,4) zeros(1,4)];stem(n,x);title('Square Wave sequence, n= 0.....31');figureFs=16000;freqz(n,x,1024,Fs);figure
Fs=16000Hz Resolution= 1024
2.
uiopen('C:\Users\Sean\Downloads\Chipmunks_sound-Uday-1052330468.wav',1)[x,Fs,nbits]=wavread('C:\Users\Sean\Downloads\Chipmunks_sound-Uday-1052330468.wav');t=0:1/Fs:(length(x)-1)/Fs;subplot(211);plot(t,x);subplot(212);specgram(x,512,Fs,hamming(256),128);figuretitle('Figure 1. Spectrogram plot of waveform chipmunks sound')
b=[ 0.0947 0.2841 0.2841 0.0947]a=[ 1.0000 -0.713 0.6287 -0.1581] H=fft2(b,512,512);Hlog=log(1+abs(H));u=-256:255;v=-256:255;[u,v]=meshgrid(u,v);subplot(221);imagesc([Hlog(257:512,257:512),Hlog(257:512,256)]);axis offsubplot(222);mesh(u,v,[Hlog(257:512,257:512),Hlog(257:512,1:256);Hlog(1:256,257:512) Hlog(1:256,1:256)]);title('Filter coefficient:');title(' b=[ 0.0947 0.2841 0.2841 0.0947]');figure H=fft2(a,512,512);Hlog=log(1+abs(H));u=-256:255;v=-256:255;[u,v]=meshgrid(u,v);subplot(221);imagesc([Hlog(257:512,257:512),Hlog(257:512,256)]);axis offsubplot(222);mesh(u,v,[Hlog(257:512,257:512),Hlog(257:512,1:256);Hlog(1:256,257:512) Hlog(1:256,1:256)]);title('Filter coefficient:');title('a=[ 1.0000 -0.713 0.6287 -0.1581]');
%3.1b=[1];a=[0.9 0.36];Fs=8000;freqz(b,a,512,Fs)figure
%3.2b=[1];a=[0.8 -0.25];Fs=8000;freqz(b,a,512,Fs)figure
%3.3b=1;a=[ 1 -1.4 1.13 ];Fs=8000;freqz(b,a,512,Fs)
Assessmentimg = imread('puppy_gray.jpg','jpg');X =fftshift(img(:,:,2));X1=fft2(X);Xabs=abs(fftshift(X1));Xlog=100*log(1+Xabs); subplot(221);colormap(gray);imagesc(img);title('Original Image')axis off; subplot(222);colormap(gray);imagesc(Xlog);title('Corresponding Spectrum')axis off; subplot(223);colormap(gray(256));imagesc(angle(X1));title('Magnitude Spectrum')axis off figuresubplot(221)h=[-1 -1 -1; -1 8 -1; -1 -1 -1];H=fft2(h,512,512);Hlog=log(1+abs(H));u=-256:255;v=-256:255;[u,v]=meshgrid(u,v);subplot(221);imagesc([Hlog(257:512,257:512),Hlog(257:512,256)]);axis offsubplot(222);mesh(u,v,[Hlog(257:512,257:512),Hlog(257:512,1:256);Hlog(1:256,257:512) Hlog(1:256,1:256)]);
