Propeller Head Plaza

RE: Q:

130.199.3.130

In Reply to: RE: Q: posted by gymwear5@hotmail.com on March 24, 2008 at 12:43:41

gymwear: ""
By definition any time varying function can be converted to a a frequency domain function via the Fourier Transform, and the voltage of an audio signal is certainly a time varying function... A digitally sampled signal leads to a Discrete Fourier Transform and an FFT (Fast Fourier Transform) is just a speedy lossless way to calculate a DFT. By the way - it works the other way, too. A frequency response that contains phase information can be converted to a time varying function. ""
I will respond with a question...Is it possible for two different time varying voltage waveforms to have the same spectral characteristics as viewed on an FFT?
IOW, if I use an FFT to examine a multi-sine component mix that goes into a "black box", and measure again as it exits the "black box", am I guaranteed that identical spectral analysis between input and output guarantees identical waveforms?
If I choose two black boxes, and only one of them delays one of the sines 45 degrees, can I spot that using the FFT? It would be obvious using a differential voltage comparison..
Cheers, John

Edits: 03/25/08

Follow Ups:

RE: Q: long.... - gymwear5@hotmail.com 11:14:12 03/25/08 (1)
- RE: Q: long.... - jneutron 12:21:14 03/25/08 (0)

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