harmonics analyze

[yogui]

Hello,

I did a FFT and I obtained a power spectrum. I would like to know the harmonics' frequencies. Are there a VI to do this ??

Thank you

[altenbach]

Yes, try the "Harmonic Anayzer.vi", it's in the "Advanced ... Signal Processing ... Frequency Domain" palette. 🙂

Message Edited by altenbach on 07-13-2005 09:22 AM

[Dr._Imad]

Theortically, for a single frequency waveform, you should have 1 peak at the fundamenmtal frequency.  If the signal contains harmonics, you should also see peaks at the harmonic frequencies.

You can also use the

Harmonic Distortion Analyzer.vi

[yogui]

Yes, I used harmonic analyzer. But I have a problem. On the graphe, my fundamental frequency is 500 Hz but in the option "detected fundamental frequency", I have 0,1705. Are there adjustments to do ????

Thank you

[yogui]

Hello,

I tried an other thing. I used the VI "harmonic analyzer" for a signal sinus, and I have the good fundamental frequency. But with a spectrum, it doesn't work ? I don't understand why ?

Thank you

[Dr._Imad]

You may want to attach your code for examination.

[yogui]

Yes.

[Dr._Imad]

The signal input to the harmonic distortion analyzer.vi   is the time domain signal.

in your example, attach the signal out of the   "formula waveform .vi" directly to the   signal in   of the  harmonic distortion analyzer.vi  .   (not the output of the FFT) 

[yogui]

Ok.

But If I want to know the frequencies of my fundamental frequency and my harmonics, how must I do (without looking at the graphes) ? I can't use harmonic_distorsion_analyser.vi ?

Thank you.

[Dr._Imad]

The  components level output should indicate the amplitudes of the harmonics detected, including the DC level.

You need to plot really for visulization and to make sure the results do make sense.