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Discussion Groups | Matlab DSP | FFT Magnitude doubt

Technical discussion about Matlab and issues related to Digital Signal Processing.

  

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FFT Magnitude doubt - Sonia Ramwaswamy - May 27 14:04:00 2003



Hi

Sorry there was some problem with previous mail. Its not == but = only. I dont
know hot it got changed. Any how find below the new piece of code.

*********************************************************
clear all;
clc;
Fs=100;
t=[0:100]/Fs;
s1=sin(2*pi*5*t);
s2=sin(2*pi*10*t);
s=(s1+s2);
figure(1);
plot(t,s)
N=1024;
S=fft(s,N);
w=((0:((N/2)-1))/(N/2))*(Fs/2);
figure(2);
plot(w,abs([S(1:(N/2))']))
xlabel('FREQUENCY');
Ylabel('Magnitude');
*******************************************************

Now the magnitude of the FFT curve is 50. But the input signal is having
amplitude of 1 in both the cases. Then how come during FFT this thing got
magnified to 50.
Can anybody explain this thing?

Sonia




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