Center of gravity of FFT shape

[ceties]

Hello I have following question. I have incoming signal and I want to compute the most important frequency. Extract Single Tone Information.vi extracts only the highest frequency from FFT and I want to compute something like center of gravity of the FFT shape.

Thx for any help

Message Edited by ceties on 02-12-2007 07:08 AM

[Rudi_N]

Ceties:

Are you trying to calculate the center frequency as described here? If so, how would you determine the lower and upper cutoff frequencies? Please let me know if I misunderstood your question.

Rudi N.

[ceties]

Hello Rudi,

We are estimating frequency from incoming signal. It isn't worth to take the maximum frequency itself but better is to set neighbourhood around this max frequency
and compute average of surrounding frequencies. I was wondering if there is some function in LabView but finally I haven't found anything so I wrote my own function.

It works following. Wipes off DC part of the signal. Than finds the maximum frequency and checks how many points are on the left side and right side. If it is less than
neighbourhood entered by user it takes the smallest possible neighbourhood. Then it calculates something like centroid.

thx

[Rudi_N]

ceties:

I looked at the attached VI and it seems like you were indeed able to achieve what you were trying to do. Please let me know if I can help further.

Regards,

Rudi N.

[ceties]

It works perfect. I posted it just in case somebody would face same problem.

[Rudi_N]

Thank you very much !!!