[sdiy] Measuring Audio Sine Purity

[Scott Gravenhorst]

How would a DIY person measure the purity of a sine wave beyond using a
spectrum analyzer?  To give a figure of sine purity, of distortion (THD?) ?

Say you have an oscillator you built, it's supposed to be a sine oscillator
and you'd like to know just how pure it is.  What would you use?

I've used RMAA to analyze a wav file of a sine signal, but that doesn't
give purity numbers, it just gives the spectrum.  

Is there software that might be used with a good sound card? 
(understanding, of course, that soundcard artifacts will present themselves
in the results)

I imagine that there is expensive hardware, but that's out of the question
for me.

-- ScottG
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-- Scott Gravenhorst
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