[ntp:questions] Using NTP to calibrate sound app

jimp at specsol.spam.sux.com jimp at specsol.spam.sux.com
Sun Jan 27 21:00:11 UTC 2013

David Taylor <david-taylor at blueyonder.co.uk.invalid> wrote:
> On 27/01/2013 19:33, unruh wrote:
>> On 2013-01-27, no-one at no-place.org <no-one at no-place.org> wrote:
> []
>>> In case you are wondering, my app is a professional piano tuning app.
>>> The standard in this industry is that tuning devices should be
>>> accurate to 12 parts per million.  I know that is probably overkill
>>> for tuning pianos, but that is what the professionals expect from
>>> their equipment.
>> Ah. I would expect 1 cent, which is more like 500PPM.
> 1% (10,000 ppm) is a 4.4 cycles per second beat at 440 Hz!  Completely 
> unacceptable.  You want an imperceptible beat, ideally, well under 1 Hz. 
>  Agreed that 12 ppm is overkill.

The general rule of thumb for metrology is that your instrument should be
at least an order of magnitude better than the allowable error, i.e. if
your allowed error is 1%, your instrument should be capable of measuring
to an accuracy of at least 0.1% for the measurement to be meaningful.

More information about the questions mailing list