how can i add zero padding to DFT

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Moshe
Moshe on 1 May 2016
Answered: Star Strider on 1 May 2016
Hi all, i write code that doing DFT for signal see code here:
f0=46.875;
W0=2*pi*f0;
Fs=1000;
T=1/Fs;
NFFT=512;
FFTperiod=NFFT*T;
t=(0:NFFT-1)*T;
str=['FFT period is ',num2str(FFTperiod), ' seconds'];
Freq=10*1/FFTperiod
strFreq =['Frequency is ', num2str(Freq), ' Hz'];
Freqbin =1/FFTperiod
strFreqbin =['FFT frequency bin is ',num2str(1/FFTperiod), ' Hz'];
strFreqNyquist =['FNyquist is ',num2str(1/FFTperiod*512), ' Hz'];
disp(str);
disp(strFreq);
disp(strFreqbin);
disp(strFreqNyquist);
x_t=sin(W0*t);
subplot(3,1,1)
plot(t,x_t);
title('time domain signal')
xlabel('Time')
ylabel('Amplitude')
Y=fft(x_t,NFFT)/NFFT;
f=Fs/2*linspace(0,1,NFFT/2);
subplot(3,1,2);
plot(f,abs(Y(1:NFFT/2)))
title('freq domain')
xlabel('Hz')
ylabel('Amplitude')
To this code i want to plot new graph with zero padding on the signal, that Change the length of the series to 4096.
can some one advise me how to do it?

Answers (2)

Azzi Abdelmalek
Azzi Abdelmalek on 1 May 2016
x=[1 2 3]
y=[x zeros(1,10-numel(x))]

Star Strider
Star Strider on 1 May 2016
Probably the best way is to use the nextpow2 function. See this documentation for fft for an illustration.

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