Phase Meter

fabiopertile · Joined: Jan 21, 2010 Posts: 3 Location: Melbourne

Anyone know how to build a phase meter?
Scope does this very nicely in a visual form, but what I'm after is the ability to stream data expressing the phase (0-180 degrees) between left and right of a signal.. Any help would be awesome..

thanks

EdisonRex · Posted: Thu Jan 21, 2010 5:56 am Post subject:

You might try reading this nasa paper for some ideas.

There are a couple of ways to go about it, but the problem gets tougher when you aren't dealing with two static frequencies.

It certainly will involve FFT of the two signals, although there are varying techniques for deriving differential phase information.

Seems like an interesting problem to solve.

fabiopertile · Joined: Jan 21, 2010 Posts: 3 Location: Melbourne

thanks EdisonRex,
Yes, ffft will certainly be involved.
I had a quick skim over the paper. Very interesting stuff.
Wouldn't it be great if scope had output data to work with?

EdisonRex · Posted: Thu Jan 21, 2010 6:12 am Post subject:

yeah, wouldn't that be nice. Either as two streams of pulses, a single PWM stream representing the difference in phase at zero crossing, or just numbers. Ah well. You know they're doing some of this stuff in Scope just to render the scope trace.

fabiopertile · Joined: Jan 21, 2010 Posts: 3 Location: Melbourne

I was sent this in another forum.
Perhaps a good start.
It does measure and display difference from 0 degrees (mono)

But, when you feed perfectly out of phase audio it expresses only in the + range.

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