Don A. Gilmore wrote: > ...Obviously the largest, slowest waves would be from the Big Daddy A0 > string > at 27.5 Hz. Then the counter would read 10,000,000 / 27.5 = 363,636 > pulses. > > The resolution of the counter is, obviously, one count (it can't count > fractions of a count, only integers). The frequency at one cent above > A0 is > > f = 27.5 x 2^(1/1200) = 27.5159 Hz > > This results in a count of 10,000,000 / 27.5159 = 363,426. This differs > from the other count by > > 363,636 - 363,426 = 210 pulses > > That's 210 pulses difference in reading to detune the note by just one > cent. I agree. So one pulse difference (the smallest difference that can be read) would be 1/210 of a cent, not 1/6000 of a cent, as you claimed. And even that requires that you be able to trigger your counter to an uncertainty of no more than 100 nanoseconds, which is hard to believe for a voltage that takes over 36,000,000 nanoseconds to rise through the trigger threshold. No way, man! In fact, if you derive your measurement from the period of a single cycle of 27.5 Hz and don't average over multiple periods, your accuracy is probably no better than 2 full cents at A0. Partials can be picked up by even the crappiest pickup, and these partials will distort the sine wave of the fundamental so that the one-shot triggering time has an uncertainly of many many clock pulses. Robert Scott Real-Time Specialties
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