From: "John Jardine"
Subject: Re: Audio Phase meter cct wanted
Date: Mon, 18 Nov 2002 12:42:32 -0000
NNTP-Posting-Date: 18 Nov 2002 12:31:08 GMT
X-Newsreader: Microsoft Outlook Express 5.00.2615.200
Tom Bruhns wrote in message
> Very simple circuit: digitizer, feeding a processor. In the
> processor, do a DFT (e.g. Goertzel algorithm) on the frequency you're
> interested in. If you run the algorithm on two inputs at the same
> time, you can easily get the (apparent) phase difference; you can
> pretty easily account for non-simultaneous sampling if you want. I'd
> guess pretty much any processor with a hardware multiply could do the
> task for audio frequencies, one freq at a time. If you do an FFT
> instead of DFT, you can have a whole band of freqs. Depending on the
> accuracy you need and the speed, even a built-in 8-bit ADC could be
> enough, making for very few parts. Lots of options for the display.
> "Jeff" wrote in message
> > I need a simple circuit to measure relative phase of audio tones, but
> > accurately than using scope patterns. Perhaps some sort of audio squarer
> > with phase comparator and meter output. Has anyone seen such a circuit?
> > Thanks.
> > JEFF
> > ZL3TNV
Looks interesting. I'd seen (a suggestion of) Goertzel's use wrt commercial
LRC meters final phase extraction but had thought the Goertel was just a
sharp bandpass filter?. Using say alternate, 'zig zag' sampled signals, how
does the phase info' present itself?.