frequency to time domain conversion

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Muhammad Ali Qadar 2014-5-13

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https://ww2.mathworks.cn/matlabcentral/answers/129423-frequency-to-time-domain-conversion

评论： dpb 2014-5-15

hi,

I have some data in text file, I want to read that data and convert the data from frequency to time domain. the data is like this

 Frequency [Hz]           Current(A)     
000000000000E+07   2.500234034000E-06         
018679245283E+07   2.546990258195E-06        
074716981132E+07   2.687277097052E-06 
149433962264E+07   2.874370653929E-06 
242830188679E+07   3.108313963777E-06 
336226415094E+07   3.342348535650E-06

I already tried the Wizard, load, fopen , fread, textscan,

suggestion please

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Muhammad Ali Qadar 2014-5-15

@dpb, I really can not understand whats going on, is there is no example that could show this

dpb 2014-5-15

Any text on the FFT or tutorial on the internet. The problem is that if you have only the PSD of a real time signal you've lost the underlying phase data and therefore have no way of regenerating the original time history any longer. You just don't have enough information left on hand.

The math is such that to generate a real output from the IFFT the input must be complex conjugate symmetric and you have no imaginary component from which to build a meaningful conjugate as the PSD is the amplitude-only result of the FFT; the phase has been mushed out.

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