FFT

[jyothi prasad]

sir

i am determining natural frequency of a beam ,i am using FFT for that i.e,in fft the corresponding X-axis value of the highest peak in FFT is the natural frequency.my question is i can see this peak but is there any sub-vi which gives this x-axis value corresponding to highest peak in FFT.

[LV_Pro]

The output of the FFT is just an array of values. The "spacing" in frequency of each member of the array is based on how big the array is versas the original sampling frequency. There is a peak detector vi in the "Signal Operations" part in the LabVIEW Full Development system that will give the index of the peak.

[Ravi_Shankar]

Check the attached Example Code.

It shows the FFT and corresponding Peaks. (Both Frequency and Amplitude)

[Coq_Rouge]

Take a look at this program. It is a general FFT prog. It sums up almost all basic Labview FFT functions. And not a single Express VI is used. It is quite old made in Labview 6i, but recompiled to 8.6