How to increase amplitude of a peak in fft in MATLAB?

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Payal Arora
Payal Arora 2013-7-23
Hello Everybody,
I am writing following code to plot fft in matlab from the ascii values. But i am getting less amplitude of the peak(as i get from the other software). How can i increase the amplitude? or is it a problem of windowing in fft? please suggest..am i doing right or wrong?
the code is following..
I = load('data1.asc');
for i = 1:2048
x = I(:,2);
end
plot(x)
Fs = 40000;
T = 1/Fs;
L = 2000;
NFFT = 2^nextpow2(L);
Y = abs(fft(x,NFFT))/L;
f = Fs/2*linspace(0,1,NFFT/2+1);
figure, plot(f,2*abs(Y(1:NFFT/2+1)))
xlabel('Frequency (Hz)')
ylabel('Magnitude')

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回答（1 个）

Dishant Arora
Dishant Arora 2013-7-23
编辑：Dishant Arora 2013-7-24
In the other software you might be plotting fft against indices and here you are doing it differently i.e fft vs frequency samples. you can try below mentioned code to get the desired result.
Y = abs(fft(x));
plot(y)
  1 个评论
Dishant Arora
Dishant Arora 2013-7-24
Also you can omit the for loop, simply use:
x = I(:,2);
and there's no need for NFFT as your data length is already in powers of 2.

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