How to find phase difference?

[sbomy]

I measured accelerations using 4 accelerometers at the same time (as attached *.txt file).

Based on the FFT analysis, all of them has 29 and 58 Hz as dominant frequencies

(*.jpg file shows the time domain signal, corresponding to the second column in *.txt file,  and its FFT from the second accelerometer.).

In order to use the measured signals as the input to a FE model, I want to find the phase differences among them.

I found one program source to find the phase difference, but that program is only for very smooth sine wave, not for my case.

Should I filter out the noise of high frequency to find phase difference more easily?

Hope to see a helper for my problem soon. Thank you.

[Hillman]

Hi Sbomy,

Good afternoon and I hope your well today.

Thanks for the post.

I have found a VI and tested it from the NI Community pages,

LabVIEW VI Mathematically Calculates Phase Between Waveforms

Below is a picture of the two waveforms I compared, a noise sinewave vs a non multiple frequency clean sinewave... I also tried it with squarewaves etc and it seemed to perform well.

Please let me know your thoughts, 

Message Edited by Hillman on 05-14-2009 01:17 PM

[sbomy]

Dear Hillman ,

Thank you for the post. Could you tell me how I can read my measured signal in this program?

Sorry for that I am a novice to labview. Thank you.

Soobum

[Hillman]

Hi Sbomy

Good afternoon and I hope your well today.

I am sorry but I dont understand your question?

Are you asking how to get your acquired data into the DBL array - orange wire? to connect as the input waveforms?

[sbomy]

Dear James,

Yes, how can I put in measured signal (as attachmed) in DBL array?

Thank you.

[Hillman]

Hi Sbomy,

Good Morning and I hope your well today.

Are you talking about the  text file attached?

How did you generate it? using LabVIEW Express VI?

Below would be my suggestion, use the Read from measurement file Express VI and then convert dynamic data type to DBL

 

Please let me know how you get on, and if no joys - more details on how you generated the file and can you attach the file in a zip so I downlaod it?

Message Edited by Hillman on 05-15-2009 11:11 AM