Phase measurement

Hi Sander:

How about simply substracting both signals and then sending them to an absolute value. This should give you an average of your phase shift that can be fed to a lookup table to represent a number.

I guess I need to know more about your application.

Miguel

Miguel's idea would work, but it would have to be calibrated using a sort of mapping approach. You would have to use a bunch of test cases where the phase shift values are known, and use the corresponding outputs to generate some kind of best-fit curve for mapping the resulting values to a phase shift number that makes sense.

Hi Sander,

If you still need this measurement, perhaps you could use the method shown in my post:

https://ez.analog.com/thread/16947

Here I measured the phase shift of a voltage waveform with respect to current, to get the phase of an unknown impedance. The measurement begins by phase-locking two VCOs to the current waveform. One VCO is in-phase with the current, the other 90 degrees away. Next, multiply the in-phase and quadrature VCO outputs by the voltage waveform, then low-pass filter each result. This gives the voltage's 0 degree (A) and 90 degree (B) amplitudes, respectively. Finally, calculate phase = arc-tangent (B/A). I use a Taylor series to figure the arc-tangent. It can measure up to a + or - 45 degree shift.

Bob

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