Interchannel delay and phase measurement

[JacktheLad]

Hi all,

Below is my latest vi, which I am using to measure the phase shift across the RC circuit. The values I am getting each time I run the program have an error of 0-0.3 radians. When testing for interchannel delay (i.e I put the two analog inputs at the same point on the RC circuit expecting the same readings). However the delay (measured also in radians of phase shift) varies 0-0.3.

It appears that error is related to the interchannel delay but they are not constant (each run the error is different). Can anyone provide me with insight on how to correct this?

If someone could also check the program to see if anything is amiss there.

Sorry the explanation is poor I am having trouble wording the problem. Please ask for any more details. Feedback/advice as always would be hugely appreciated.

[rsw]

Hi,

I think I understand the issue you're seeing, I'd suggest taking a look at the Example Finder (Help > Find Examples) and navigate to "Hardware Input and Output > DaqMX" and looking at those examples to create your program using lower level DAQmx functions as the program flow all looks correct to me.

Kind Regards, 

[TLE]

You can account for interchannel delay using the "AI Convert Rate" property available in DAQmx.  Invert it (to get how long the interchannel delay is) and multiply it by the current frequency (in radians per sec) and subtract that from your phase calculation.