Question

Write Matlab Code Only

Generate a multi-tone sinusoidal signal with f1=2000Hz and f2=4000Hz, then by sampling generate the Oversampled and Undersampled version of it and display the frequency response also.

Answer 1

clc
clear all
%% fso is the oversampling frequency
fso=15000;
%% time defined
to=0:1/fso:0.1;
%% multi tone signal defined
xo=sin(2*pi*2000*to)+sin(2*pi*4000*to);
%% fast fourier transform perform on the signal to find
%% frequency domain
fftxo=fft(xo)/length(xo);
%% fftshift shifts the transform toward the center
fo = linspace(-fso/2,fso/2,length(xo));
%% time domain representation of the oversampled signal defined
subplot(4,1,1)
stem(to,xo);
%% xlabel ylabel are used for naming axis and plot
xlabel('time');
ylabel('magnitude');
title('time domain representation of the oversampled signal at fs=15000Hz');

%% frequency domain representation of the oversampled signal defined
subplot(4,1,2)
plot(fo,fftshift(abs(fftxo)));
%% xlabel ylabel are used for naming axis and plot
xlabel('frequency');
ylabel('magnitude');
title('frequency domain representation of the oversampled signal at fs=15000Hz');

%% fsu is the undersampling frequency
fsu=3000;
%% time defined
tu=0:1/fsu:1;
%% multi tone signal defined
xu=sin(2*pi*2000*tu)+sin(2*pi*4000*tu);
%% fast fourier transform perform on the signal to find
%% frequency domain
fftxu=fft(xu)/length(xu);
%% fftshift shifts the transform toward the center
fu = linspace(-fsu/2,fsu/2,length(xu));
%% time domain representation of the undersampled signal defined
subplot(4,1,3)
stem(tu,xu);
%% xlabel ylabel are used for naming axis and plot
xlabel('time');
ylabel('magnitude');
title('time domain representation of the undersampled signal at fs=3000Hz');

%% frequency domain representation of the undersampled signal defined
subplot(4,1,4)
plot(fu,fftshift(abs(fftxu)));
%% xlabel ylabel are used for naming axis and plot
xlabel('frequency');
ylabel('magnitude');
title('frequency domain representation of the undersampled signal at fs=3000Hz');