PXI-6251 Phase Angle

[TomJr]

Good Day,

I am currently using a PXI-6251 module and I need to measure Phase Angle between two sinusoidal waveforms. I have done a lot of searching and can not find much. If anyone is able to help I would appreciate it.

TIA,

TomJr

[lrallen]

TomJr,

Have you looked at the Signal Processing >> Waveform Measurements pallette?  Here you will find Dual Channel Spectral Measurement Express VI.  This can give you the phase between two input signals.  Let me know if this works for you.

Regards,

Lon

[TomJr]

Irallen,

Thanks for the tip, I will check it out.

Regards,

TomJr

[Tom_W_[DE]]

Hi TomJr-

I'm not sure if it will be very significant, but there will be some phase difference introduced into your sampled signals due to the fact that the input lines are MUX'd through a single PGIA and ADC.  This means that there will inherently be some skew between channels that you may want to account for. 

The easiest way to accomplish this is to query the AI.Convert.Rate propery as shown below. 

This value is the frequency of the clock that initiates samples from each channel in succession, so the reciprocal will represent the system-introduced phase difference in the sampled values.  If the amount of time introduced by this multiplexing is significant you might want to manually add it to the value you calculate with lrallen's suggestion.  Alternatively, you could use a simultaneously sampled S Series board to remove these effects if they are very significant in your system.

Hopefully this helps-

Message Edited by Tom W [DE] on 03-06-2006 01:15 PM