how can i add zero padding to DFT

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Moshe
Moshe 2016-5-1
回答： Star Strider 2016-5-1
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?

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回答（2 个）

Azzi Abdelmalek
Azzi Abdelmalek 2016-5-1
x=[1 2 3]
y=[x zeros(1,10-numel(x))]
Star Strider
Star Strider 2016-5-1
Probably the best way is to use the nextpow2 function. See this documentation for fft for an illustration.

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