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Aymen
Posts:
5
Registered:
10/28/09
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generate Time signal from a given PSD
Posted:
Nov 3, 2009 10:04 AM
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Hello people,
i'm a novice in the field of signal processing and this problem maybe easy for you ...
I want to extract a stochastic time signal from a given PSD using the inverse fourier transform.
the PSD contains frequencies from 0 to 2557,5 and i'm trying to generate a time signal corresponding to that PSD (it goes over a time period of 35 sec ).
I think i'm having a scaling problem but i don't know where ...
could you please help me with this :
First of all i tried to generate random phases for my PSD-amplitudes to be able to perform the ifft.
M=[freq Amplitude]; %PSD Matrix
a=sqrt(Amplitude);
phase = 2*pi*rand(size(a)); %random phases in [0 2*pi]
Y=a.*exp(j*phase); % complex vector for ifft
signal = ifft(Y,N); %inverse Fourier Transform, problem in N ??????
t=0:35/(N-1):35; %time vector
plot(t,real(signal)) %plot of time signal
my time vector sould have 179200 values between 0 sec and 35 sec
which N should i use to get the correct answer ?
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