[ntp:questions] measuring frequency
Terje Mathisen
"terje.mathisen at tmsw.no" at ntp.org
Tue Feb 12 13:41:16 UTC 2013
robert bristow-johnson wrote:
> On 2/11/13 6:48 PM, unruh wrote:
>> ["Followup-To:" header set to comp.protocols.time.ntp.]
>
> why do that?
>
>
> hey guys, fix the Newsgroup: header here.
>
> On 2/11/13 6:48 PM, unruh wrote:
> > ...
> > Yes. However what you can do is to filter out the all but the strongest
> > harmonic, and count which harmonic number it is.
>
> how do you know what the harmonic number is? how would that information
> be determined in the general case.
This is what FFT was developed for, a single piano key will turn up as a
somewhat smeared comb function, with peaks around the fundamental
frequency plus the main harmonics.
Doing multiple FFTs should also show you any time-based change in pitch
of the various peaks.
Terje
--
- <Terje.Mathisen at tmsw.no>
"almost all programming can be viewed as an exercise in caching"
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