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Furie series

I have any periodical signal. I want expand it to
Furie series (get harmonics of it).
There is any vi that make this?

Thanks,
Nadav Chernin.
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Message 1 of 9
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If you have the Advanced Analysis add-on the answer is, yes. Look in the library "2dsp.llb". That's where you'll find them.

Mike...

PS: The correct spelling is Fourier--he was French.

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I have 2dsp.llb. Can you give me name of this vi?
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Well, that depends on what exactly it is that you want. If you want a power spectrum of the input data, there's a VI in 2dsp.llb called "Power Spectrum.vi". If, on the other hand, you want the amplitude and/or phase spectrum of the input signal, the library 0measdsp.llb contains the VI "Amplitude and Phase Spectrum.vi".

Which one you use depends on what you need. If you're not sure what you need, start with the Amplitude and Phase Spectrum.vi.

Mike...

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I want get amplitudes and frequencies of harmonics (2 vectors). Spectrum is something another.
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If you checkout the VI I suggested this is exactly what you get. An amplitude array, and a frequency array.

Mike...

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I have little problem - amplitudes that i get are with absolute value, but i need for Fourier Series the real values of amplitudes. Do you know how get real signs of them.
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I'm sorry, I guess I don't understand what you need. The referenced routine calculates the Fourier series for the input data and outputs the amplitudes in the appropriate units.

Mike...

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"... after all, He's not a tame lion..."

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The problem seems to one of formatting the DFT result. The FFT returns a complex result, which can be displayed as magnitude/phase or real/imaginary. To get something analogous to Fourier series coefficients, use the real/imaginary format--the real part will be your cosine coefficient and the imaginary part will be your sine coefficient. You might have to worry about converting from RMS to peak by multiplying by sqrt(2) and perhaps another factor of 2 if you use a double-sided FFT. For an easy single-sided result on a waveform input, try the FFT Spectrum (Real/Im).vi in vi.lib\measure\maspectr.llb. If you prefer the array-based FFTs in 2dsp.llb, you will need to use the Polar to Complex and/or Complex to Re
/Im math primitives to convert your results.
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