is my code logically correct? will i get the same output when i do it manually?

clear;

clc;

close all;

x = input('Enter a sequence: ');

figure(1);

subplot(3,1,1);

stem(x);

ylabel('Amplitude');

xlabel('Samples');

title('Input sequence');

% Decimation by 4

y1 = resample(x, 1, 4);

subplot(3,1,2);

stem(y1);

ylabel('Amplitude');

xlabel('Samples');

title('Decimation by 4 - Sequence');

% Interpolation by 4

y2 = resample(x, 4, 1);

subplot(3,1,3);

stem(y2);

ylabel('Amplitude');

xlabel('Samples');

title('Interpolation by 4 - Sequence');

% Sinusoidal signal

fs = 10;

N = 50;

f = 1;

n = 0:N-1;

Ts = 1/fs;

x1 = sin(2*pi*f*Ts*n);

figure(2);

% Sine signal

subplot(3,1,1);

stem(x1);

ylabel('Amplitude');

xlabel('Samples');

title('Sine signal');

% Decimation of sinusoidal signal by 4

yd_decimate = resample(x1, 1, 4);

subplot(3,1,2);

stem(yd_decimate);

ylabel('Amplitude');

xlabel('Samples');

title('Decimation by 4 - Sinusoidal signal');

% Interpolation of sinusoidal signal by 4

yd_interpolate = resample(x1, 4, 1);

subplot(3,1,3);

stem(yd_interpolate);

ylabel('Amplitude');

xlabel('Samples');

title('Interpolation by 4 - Sinusoidal signal');

Answer 1

[Mathieu NOE]

hello

I wondered if the exercise was more to prove that decimating then resampling (by the same factor) would give (almost) the original signal

if yes , you have to modify your code , like

% Interpolation of sinusoidal signal by 4
yd_interpolate = resample(x1, 4, 1);

must be changed into

% Interpolation of sinusoidal signal by 4
yd_interpolate = resample(yd_decimate, 4, 1);

(otherwise you are resampling the input signal not the decimated signal)

all the best

clear;
clc;
close all;
x = input('Enter a sequence: ');
figure(1);
subplot(3,1,1);
stem(x);
ylabel('Amplitude');
xlabel('Samples');
title('Input sequence');
% Decimation by 4
y1 = resample(x, 1, 4);
subplot(3,1,2);
stem(y1);
ylabel('Amplitude');
xlabel('Samples');
title('Decimation by 4 - Sequence');
% Interpolation by 4
% y2 = resample(x, 4, 1);
y2 = resample(y1, 4, 1);
subplot(3,1,3);
stem(y2);
ylabel('Amplitude');
xlabel('Samples');
title('Interpolation by 4 - Sequence');
% Sinusoidal signal
fs = 10;
N = 50;
f = 1;
n = 0:N-1;
Ts = 1/fs;
x1 = sin(2*pi*f*Ts*n);
figure(2);
% Sine signal
subplot(3,1,1);
stem(x1);
ylabel('Amplitude');
xlabel('Samples');
title('Sine signal');
% Decimation of sinusoidal signal by 4
yd_decimate = resample(x1, 1, 4);
subplot(3,1,2);
stem(yd_decimate);
ylabel('Amplitude');
xlabel('Samples');
title('Decimation by 4 - Sinusoidal signal');
% Interpolation of sinusoidal signal by 4
% yd_interpolate = resample(x1, 4, 1);
yd_interpolate = resample(yd_decimate, 4, 1);
subplot(3,1,3);
stem(yd_interpolate);
ylabel('Amplitude');
xlabel('Samples');
title('Interpolation by 4 - Sinusoidal signal');

[Mathieu NOE]

hello again

problem solved ?