FFT and Inverse FFT question

[therealkilkenny]

Hi,

Couldn't find the answer to this question anywhere. I've attached a vi where i create a waveform, zero pad it to give a corresponding required delta f step, fft it and then inverse fft it. The problem here is that the resultant waveform from the inverse fft is not the same as the original one (either in amplitude or in time).

What i ultimately want to do is to take a pulse, fft it, modify the amplitude fft and convert back to the original waveform. Thus i will be able to modify the frequency content of waveforms.

Any suggestions?

Thanks, Phil

[johnsold]

Phil,

Use the true FFT VI rather than the scaled Amplitude and Phase Spectrum VI. When I substitute that and the Complex to Polar conversion from the Numeric palette, it seems to return the windowed time domain signal.

Lynn

[therealkilkenny]

Hi Lynne,

Simple but effective. Thanks.

Phil