[ntp:questions] measuring frequency

Ivan Shmakov oneingray at gmail.com
Fri Feb 8 07:34:14 UTC 2013

>>>>> David Woolley <david at ex.djwhome.demon.invalid> writes:

	[Cross-posting, and setting Followup-To:, to news:comp.dsp.]


 > In Fourier terms, the spectral width of a piano note is going to be
 > more than 12ppm and depend on the exact interval over which you
 > measure it.  I would also suspect that the zero crossing interval
 > changes significantly during the note, particularly at the start.

	As per my experience with guitar signals, such a waveform is
	likely to cross zero more than once per period.  Hence, by
	counting such crossings one typically gets the frequency of one
	of the note's harmonics, and not that of the pure tone.

	BTW, is there a kind of overview of a method that could allow
	for frequency measurement for such a signal?  (Preferably one
	oriented to the uninitiated.  I can probably handle complex
	math, though.)



FSF associate member #7257	np. nkl_vietnam.mod

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