FFT (up to harmonic (n) of the 2D array

Hello 150,.

I want to record a FFT for the specific frequency range. The entrance is a 2D table in which each row represents a record. I just need phase und amplitude of the harmonics (up to the n - controllable). I didn't need too many harmonics, so I would avoid calculations and do to the amount of certain frequencies in the FFT.

I would take this VI, but y at - it an option to set a range for the FFT? Or another VI accesses Magn. & Phase for harmonics?

https://zone.NI.com/reference/en-XX/help/371361H-01/lvanls/amp_and_phase_spectrum/

VS_03 wrote:

... (or is there a better way?)

Well, if you know exactly the spectral positions and the data are clean (no spectral leakage, without periods truncated, etc.), all what you need to do is multiply with the waves of the complex unit of frequency. (See also this for the amplitude of the fundamental frequency, can be easily added for more spectral positions.) Note that the FFT is very effective, so if you need a large amount of spectral positions, it might be faster.

Tags: NI Software

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