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how to caculate coherence function correctly

I am trying to calculate coherence function of two input signals. Both of the signals contain a sine wave and  ambient noisy. The two sine waves have the same frequence and different magnitude while the two ambient noisy is non-correlation. The input signals are from a digiter which its output is 1D-array. I have tried many method but the results are always  1 at all frequence. Is  the problem  the same as knowledgeBase document: Why is the Network Functions (avg) VI's Coherence Function Output "1"?) but I sitll don't know how to do it .
can anybody give some hints or idea ?Thanks very much!
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Message 1 of 3

 Thank you for posting the doubt.

I am also searching the detail.

What I have done so far is given in one of my papers,

attached for your convenience .

You can go though gradulally.

After the publication I am working out what it explains

Take a sin wave of say 50 c/s for some duration and magnitude .

Take another  50 c/s sin wave of same duration but of higher magnitude .

The coherence is 1.

Take another sin wave of higher frequency say 100 c/s or non harmonic frequency  of 80c/s .

the coherence is 1.

Take two sin wave of same frequency , same lenth ,same magnitude but displaced with refence to  time for a fraction.The coherence is not uniformly 1.


It is stated that it represents Spectral Pwer density.

I am trying to understand myself .Once I understand I will get back to you

In the meanwhile if you find any thing further please let me know.


Dr. B P Singh



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Message 2 of 3

Please see one of my papers,

Further in next mail




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