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How to recover the original signal using ifft

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Hello everyone,
I've written a code to test the ifft function in MATLAB. However, I've noticed that ifft returns the same number of points as fft. I'm aiming to recover the original signal, which had 1000 points along with the time vector, t. How can I achieve this?
Thanks in advance for your help!
clear;clc;close all;
dt=2.5e-9;
f = 10e6;
Nfft=8*4096;
t = (0:1000-1)*dt;
sinal = sin(2*pi*f*t);
figure(1)
plot(t,sinal)
%Cálculo da fft
fftsinal=fft(sinal,Nfft);
%Transformada inversa de Fourier
sinal_recuperado = real(ifft(fftsinal,Nfft));
figure(2)
plot(1:Nfft,sinal_recuperado);
  1 Comment
Paul
Paul on 11 May 2024
Hi Enzo,
For this problem, why zero-pad the FFT to Nfft points?

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Accepted Answer

Hassaan
Hassaan on 11 May 2024
clear; clc; close all;
% Time step
dt = 2.5e-9;
% Frequency of the sine wave
f = 10e6;
% Number of points in the original signal
N = 1000;
% Time vector
t = (0:N-1) * dt;
% Original signal
sinal = sin(2*pi*f*t);
% Plot the original signal
figure(1)
plot(t, sinal)
title('Original Signal')
xlabel('Time (s)')
ylabel('Amplitude')
% Compute the FFT of the original signal
fftsinal = fft(sinal);
% Compute the IFFT to recover the signal
sinal_recuperado = real(ifft(fftsinal));
% Plot the recovered signal
figure(2)
plot(t, sinal_recuperado)
title('Recovered Signal')
xlabel('Time (s)')
ylabel('Amplitude')
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