Hello,
Below is the program I am using to measure the phase difference in an RC circuit. Simply put I generate a 2kHz sine wave in LabView and send it to the circuit using an Analog output. Then I measure the output sine wave using an analog output.I also measure this using n oscilliscope. I cna clearly measure the phase difference with the oscilliscope and know it to be approximately 1.4 radians.
Issues with the program:
Different phase difference measured each time the program is run for the circuit. It is also never correct.
Possible causes:
You will notice by looking at the vi I measure the phase from the signal generator. Should I be using a second analog input to measure the sine wave as it is outputted at the start of the circuit?
I mainly think that it is a timing issue. While the phase difference is constant each time the program it varies each on run. So the time each tone measurement begins its first measurement seems to be different each time and causes this different phase reading.
The card I am using is a PCI 6221, is there a timing issue related from switching to input and output acquistion or are they seperate.
Is there anyway to ensure that both tone measurements are measuring phase at the same point in (actual) time?
I would really appreciate any advice or alterations on the program anyone could offer me (I am a college student and LabVIEW is not on our curriculum so I have no support, yet I am using it for my project (D'oh!))
