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Produce anti-noise

Gerrit Holl gerrit at nl.linux.org
Tue Feb 3 04:50:39 EST 2004 
Josiah Carlson wrote:
> I am curious though, isn't an inverse in phase just a phase shift of 180 
> degrees?  If so, shouldn't inverting the phases of all input waveforms 
> (if we were to decompose the signal) produce an output that is 
> funnctionally an amplitude inversion?

That's only true for sin(x).

I think a phase shift is measured in time or as a fraction of the
period, not in degrees. Suppose you have a simple harmonic oscillator,
then a phase shift of a half period means you get a oscillator which
exactly cancels the first one. In the case of harmony, the oscillation
is described with trigonometric functions, so in the simplest case we
define the period to me 2*Pi (or 360 degrees). A half period would then
be Pi (180 degrees) - I think you're confused with that case...

But here, of course, we have no harmonic oscillation, and certainly not
a period of 2*Pi.

yours,
Gerrit.
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