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difference phase tension-current
skees
Member
06-09-2005 08:41 AM
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Hi,
Thank you Joris for your answer but I'm still in trouble with my mesaurement.
I've try with the VI "Extract single tone" but it doesn't work.
I can't understand how the system can measure the phase of my analogic signal (from the DAQpad) without any other signal reference.
My signal come into the Extract single tone Vi from the DAQmx assistant. It's a voltage signal and when It goes trough the VI the phase is 90°. If tried other solution, without success.
I'm using LabVIEW 7.0
Have you an example for my version or another explanation.
Thanks a lot
Thank you Joris for your answer but I'm still in trouble with my mesaurement.
I've try with the VI "Extract single tone" but it doesn't work.
I can't understand how the system can measure the phase of my analogic signal (from the DAQpad) without any other signal reference.
My signal come into the Extract single tone Vi from the DAQmx assistant. It's a voltage signal and when It goes trough the VI the phase is 90°. If tried other solution, without success.
I'm using LabVIEW 7.0
Have you an example for my version or another explanation.
Thanks a lot
JorisV
NI Employee (retired)
06-10-2005 09:04 AM
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Hi,
I don't see any problems with the example I've posted before. I've included a Daq Assistant VI that measures two voltage signals, I calculate the phase of each signal and subtract them. It works just fine. I've tested it with a PCI-daq card with a real-life signal. You can see the phase changing.
So the phase is the shift of a periodic signal, often measured referenced to its zero crossing, compared to a reference signal of the same frequency. OK, I agree, you need some kind of reference signal but it can be done mathematically. If I'm not mistaking It's just a formula that calculates the phase shift of the FFT of your signal. You can find these formaulas if you search the web but I'm not able to give you the actual code behind the Single Tone VI.
Anyway, this is the VI that calculates the Phase from signals coming from the daq assistant.
Regards.
JorisV
I don't see any problems with the example I've posted before. I've included a Daq Assistant VI that measures two voltage signals, I calculate the phase of each signal and subtract them. It works just fine. I've tested it with a PCI-daq card with a real-life signal. You can see the phase changing.
So the phase is the shift of a periodic signal, often measured referenced to its zero crossing, compared to a reference signal of the same frequency. OK, I agree, you need some kind of reference signal but it can be done mathematically. If I'm not mistaking It's just a formula that calculates the phase shift of the FFT of your signal. You can find these formaulas if you search the web but I'm not able to give you the actual code behind the Single Tone VI.
Anyway, this is the VI that calculates the Phase from signals coming from the daq assistant.
Regards.
JorisV
