Unwrap Phase from signal

[JimS]

Hi all,

I am quite new to LabVIEW, I am using it as a part of my final year project (in my mechanical engineering course)

There us one issue I am having huge difficulties with is phase measurement.

Essentially I am using sine wave signals (comparing two to find the diiference in phase) however I cannot measure the phase greater than 360 degrees. For example when the phase difference is say 420, the tone measurement gives a phase of 60 degrees. For what I am using LabVIEW for I will need to know the total phase 420.

Included is a simple vi showing this issue.

Does anybody know any solutions to this? Any help at all will be greatly appreciated.

Regards

simple phase measurement.vi

[hooovahh]

Hi all,

I am quite new to LabVIEW, I am using it as a part of my final year project (in my mechanical engineering course)

There us one issue I am having huge difficulties with is phase measurement.

Essentially I am using sine wave signals (comparing two to find the diiference in phase) however I cannot measure the phase greater than 360 degrees. For example when the phase difference is say 420, the tone measurement gives a phase of 60 degrees. For what I am using LabVIEW for I will need to know the total phase 420.

Included is a simple vi showing this issue.

Does anybody know any solutions to this? Any help at all will be greatly appreciated.

Regards

Interestingly of the 3 things you put on the block diagram (not including wires) I've never used 2 of them.

You do know that 420 degrees = 60 degrees? (or is is 420==60)

I'm not sure how you would know it is 420 degrees off instead of 60, unless you take a look at the time that each signal starts, and see how many cycles one starts before the other. I have an idea on how to do this in a FPGA type of VI but no clue how it would be done with express VIs.

[mzu]

Unwrap phase.vi may be your solution

[JimS]

mzu: the unwrap phase vi needs an array of phase inputs, I am un sure how to extract this from a sine wave signal.

hooovahh: another method I could employ is to calculate the phase, to do this I would need measure the time delay between two real signals, could you offer any ideas on how to accomplish this?

[rpursley]

mzu: the unwrap phase vi needs an array of phase inputs, I am un sure how to extract this from a sine wave signal.

hooovahh: another method I could employ is to calculate the phase, to do this I would need measure the time delay between two real signals, could you offer any ideas on how to accomplish this?

Take a look at using the Hilbert Transform to turn each of your signals into an analytic signal (original signal is real part, Hilbert transform signal is the imaginary part). Then you can get the phase of the complex number.