[PD] feedback detection

[Mathieu Bouchard]

On Mon, 21 Aug 2006, matthew jones wrote:

> cross-correlation
[...]
> This is all time domain stuff.  As Jamie says, freq domain can be harder 
> to interpret.

Cross-correlation in the time domain is the same as ordinary product by 
conjugate. This is again the Convolution Theorem, with a slight variation 
because of the little difference between convolution and 
cross-correlation.

This means that cross-correlation of two sinewaves of different 
frequencies will be zero, and cross-correlation of two sinewaves of same 
frequency will give a sinewave of that same frequency again, with an 
amplitude that is the product of the two amplitudes, and a phase that is 
the difference of the two phases. (in convolution, phases add up instead).

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| Mathieu Bouchard - tél:+1.514.383.3801 - http://artengine.ca/matju
| Freelance Digital Arts Engineer, Montréal QC Canada