How to measure relative phase of several sine wave inputs

I'm using a USB-6229 to acquire 10 sine waves, and I would like to output their rms amplitudes and relative phases. The rms amplitude is not a problem, but I wasn't sure how to go about determining the phase of one signal relative to another. Do I need to use the Frequency Response analysis step? Thanks.

Hi,
There are some functions you can use to measure the relative phase. You can either measure the phase of every signal related to another one using like you said: a frequency response function step. Using one of these to functions might do the job: “Frequency Response, Express VI” or “Frequency Response Function (Mag-Phase).vi, if you are working in LabVIEW. The first one of these functions "Frequency Response" is also found in signal express and is the one I think you are refering to.
Although this functions is use for a stimulus response approach they will give you the relative phase of Y with respect to X, “Typically, time signal X is the stimulus, and time signal Y is the response of the system. in signal express your options is the frequency response step.
I would also like to point you to some references that might serve you as reference when doing spectrum analysis: An Overview of Frequency-Domain Measurements and FFT Analysis.
Message Edited by Jaime F on 02-06-2008 11:42 AM
Jaime Hoffiz
National Instruments
Product Expert
Digital Multimeters and LCR Meters
Attachments:
frf.png ‏37 KB

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How to measure relative phase of several sine wave inputs

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