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thentangler
USA
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 Posted - 07/15/2011 : 01:59:58 AM
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Hi,
I think a user has posted this question before, but I could not find a specific answer. Perhaps some new reader might be able to give some insight. I have 2 sinusoidal waveforms that are shifted by a slight phase shift. I can calculate the phase shift if I can some how find the time delay between teh 2 curves. Right now I am manually doing it by finding the time (t) at a peak for each waveform and subtracting them to find delta t. But is there a way to automatically do this?
Also in the curve fit waveform method, there is a parameter called phase shift, but I dont know what it relates too.
I would really appreciate some help.
Thank You |
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couturier
France
291 Posts |
Posted - 07/15/2011 : 06:15:24 AM
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you can try this toolbar that computes shift between two or more datasets using cross correlation
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thentangler
USA
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Posted - 07/17/2011 : 02:52:18 AM
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Thank you very much for the reply couturier. I tried it, but I am unable to get the correct phase shift.The phase angle in degree is given as the phase shift delta t *frequency*360. When I do that with my existing data I m getting a phase angle of 1325 degrees. But when I do it manually im getting a more reasonable value of 116 degrees.
Do help please.
Thank You |
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couturier
France
291 Posts |
Posted - 07/17/2011 : 04:12:30 AM
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well, if your data are sinusoidal, maybe you can try the circular data button (with rounded arrow).
By design, cross correlation will find the max likehood shift. So 1325 degress is 3*360 + 245. With sinusoidal waveform, a 245 degree shift is also a 115 degree shift (depending on which data is shifted), which is about what you found manually. |
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thentangler
USA
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Posted - 07/27/2011 : 3:45:42 PM
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oh that makes sense. Thank You
But could you tell me how the 245 degree shift would correspond to 115 degrees?
Thanks
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Phase shift