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use absolute time in dft and fft

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This commit is contained in:
Thorsten Liebig 2011-06-08 11:23:55 +02:00
parent ca8c5eeee4
commit 36c933c208
3 changed files with 3 additions and 5 deletions
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2
matlab/DFT_time2freq.m
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@ -20,8 +20,6 @@ if numel(t) ~= numel(val)
error 'numel(t) ~= numel(val)' error 'numel(t) ~= numel(val)'
end end
% convert absolute time into relative time
t = t - t(1);
dt = t(2)-t(1); dt = t(2)-t(1);
f_val = zeros(1,numel(freq)); f_val = zeros(1,numel(freq));

3
matlab/FFT_time2freq.m
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@ -11,3 +11,6 @@ val = fft( val, NFFT)*dt;
f = 1/(2*dt) * linspace(0,1,NFFT/2+1); f = 1/(2*dt) * linspace(0,1,NFFT/2+1);
val = 2*val(1:NFFT/2+1); % single-sided spectrum val = 2*val(1:NFFT/2+1); % single-sided spectrum
%correct phase for time-shifted signals
val = val .* exp(-1j*2*pi*f * t(1));

3
matlab/ReadUI.m
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@ -53,7 +53,4 @@ for n=1:numel(filenames)
UI.FD{n}.f = freq; UI.FD{n}.f = freq;
UI.FD{n}.val = DFT_time2freq( t, val, freq ); UI.FD{n}.val = DFT_time2freq( t, val, freq );
end end
%correct phase error for time-shifted signals
UI.FD{n}.val = UI.FD{n}.val .* exp(-1j*2*pi*UI.FD{n}.f * t(1));
end end