[LAD] Determining Phase

[Rui Nuno Capela]

On Sat, 25 Jun 2011 16:23:29 +0200 (CEST), pshirkey at boosthardware.com wrote:
> Hi,
>
> Can anyone point me to a simple code example for how to determine the
> phase at a specific time in a waveform?
>
> ex. if I have a sample that is 5 seconds long and want to know the
> phase
> at 2.5 seconds
>
> I'm open to code in any language or a scripted example if such a tool
> exists. If there is an ui which has that feature I am also
> interested.
>

in general, theory i mean, phase equals delay; it can be computed 
deterministically iif the signal is a pure tone (sinusoidal) otherwise 
you must have a reference signal and referring to its fundamental 
frequency (1st order harmonic) or, when in-the-field, you can pick one 
conventional signal tone (i've been told that a 1khz is a usual choice:) 
and compare to that.

if you are to compare two known signals (often input vs. output of some 
lti transformation, eg. filter), than the computation to do is 
correlation. well, you should use fft for that, but i'm sure you know that:)

cheers
-- 
rncbc aka Rui Nuno Capela
rncbc at rncbc.org