rebuild signal from frequency domain to time domain tia sal22

[Rick T]

rebuild signal from frequency domain to time domain tia sal22

Greetings all 

I would like to rebuild a signal from the frequency domain

can this be done using fft?  If so does anyone have some 

example code?

Here's what I have so far.  I create/import a signal and plot

using the time domain.  Then I use fft to convert to 

the frequency domain and plot.  What I want to do now is 

be able to convert from the frequency domain data back to the time

domain.  Then I'll be able to export the file as a wave file 

PS: I won't have an equation to work with because I'll be importing

an audio file, and I'll be making changes when the signal is

in the frequency domain.  

But at the moment I'm just trying to convert from the 

frequency domain back to the time domain. So the third plot 

when created would look just like the first plot in the time domain 

in the example below

%time domain

%create time domain

Fs = 1000;                    % Sampling frequency

T = 1/Fs;                     % Sample time

L = 1000;                     % Length of signal

t = (0:L-1)*T;                % Time vector

y = 0.7*sin(2*pi*50*t) + sin(2*pi*120*t); 

%frequency domain

NFFT = 2^nextpow2(L); % Next power of 2 from length of y

Y = fft(y,NFFT)/L;

f = Fs/2*linspace(0,1,NFFT/2+1);

subplot(2,1,1),plot(Fs*t(1:50),y(1:50))

title('Signal ')

xlabel('time (milliseconds)')

% Plot  amplitude spectrum.

subplot(2,1,2),plot(f,2*abs(Y(1:NFFT/2+1))) 

title('Amplitude Spectrum of y(t)')

xlabel('Frequency (Hz)')

ylabel('|Y(f)|')

tia sal22

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