[sdiy] Cheap frequency counter for oscillator calibration

[ASSI]

On Monday 26 April 2010, David G. Dixon wrote:
> I have assumed that, for any
> frequency F(0), the frequency 5 cents below may be calculated
> thus:
> 
> F(-5c) = F(0)*[1-0.05*(1-2^(-1/12))]

Not quite, five cent deviation would actually be:

f(-5c) = f(0) * 2^(-5/1200)
f(+5c) = f(0) * 2^(+5/1200)

or generally:

f(x[c]) = f(0) * 2^(x/1200) # x[c] means x in cent
f(x[s]) = f(0) * 2^(s/12)   # x[s] means x in semitones

The error you made is small enough not to mess up your table too 
terribly, but if you were to try the same calculation with semitones 
or octaves you'd see it more clearly. :-)


Achim.
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