Measuring frequency and phase of a square wave using Extract Single Tone Information vi

[looloo]

Dear all,

I am trying to measure the frequency and phase of a square wave from a DAQ card using Extract Single Tone Information vi. So far the frequency could be measured correctly but there is some problems with the phase measurement.

I have attached a sample program here. I generate the square wave using Square Wave PtByPt vi. The default sample size is 1000. When I set frequency = 7.43, phase = 80, the frequency could be measured correctly but the phase is completely out. Is there anything wrong with my program? 

Thank you very much for your help.

Best regards

[Henrik_Volkers · Accepted solution]

A square wave is not a single tone 😉

If you have a square wave use the edges to do measurements. 

[looloo]

Thank you Henrik. it is possible to do it that way.

Another problem is that I need to measure the phase difference between a square wave and a sine wave from a DAQ card. They are expected to have the same frequency. For sine wave, I guess it could be done by the Extract Single Tone vi but for the square wave, do I need to do the manual calculation and compute the phase difference? Is there any other ways to accomplish that?

Thanks for the help