use absolute time in dft and fft

matlab/DFT_time2freq.m

@@ -20,8 +20,6 @@ if numel(t) ~= numel(val)
     error 'numel(t) ~= numel(val)'
 end
 
-% convert absolute time into relative time
-t = t - t(1);
 dt = t(2)-t(1);
 
 f_val = zeros(1,numel(freq));

matlab/FFT_time2freq.m

@@ -11,3 +11,6 @@ val = fft( val, NFFT)*dt;
 f = 1/(2*dt) * linspace(0,1,NFFT/2+1);
 
 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));

matlab/ReadUI.m

@@ -53,7 +53,4 @@ for n=1:numel(filenames)
         UI.FD{n}.f = freq;
         UI.FD{n}.val = DFT_time2freq( t, val, freq );
     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