[ntp:questions] Accuracy of audio tones via VOIP
spam at goes.nowhere.com
Wed Jul 17 10:46:43 UTC 2013
In article <CKdFt.91109$%u3.58105 at fx08.iad>, unruh at invalid.ca says...
> Except what he wants is a way for Joe bloggs, your everyday piano tuner,
> to calibrate his piano tuning software so that it gives 10PPM accuracy
> for frequencies. Since it is a software solution, it means that his
> clients cannot and will not have Thundbot GPSS0 or anything else, and
> any hardware purchase they are forced to make will mean that they will
> go out and buy an all-in-one piano tuning device instead.
> He has been going on with the question "How can his software reliably
> self calibrate itself to 10PPM absolute frequency standard". His idea is
> to use the test tones sent out by phone, and is worrying (as he should )
> the result of some of his clients using voip services to get those
> tones instead of standard wired phones.
> Now, I strongly suspect that his competition, who claim 10PPM accuracy
> on their ability to measure the frequency (against an absolute time
> standard) of a piano string, are just lying. And that furthermore, the
> necessity of them making those measurements to that accuracy is not
> there. But that is the challenge he has set himself. Note that he wants
> his clients to connect to that tone and to have that tone delivered
> reliably, for many minutes, in order to calibrate to that accuracy,
> while a piano string vibrates with a decay time of a second or so, and
> that he (or anyone) can then measure its to 100PPm accuracy in a second
> or so.
It ain't going to happen then. Bet he also has Oxygen Free Copper, or
Gold plated Sterling Silver speaker leads, er.. "Interconnects" too, in
his home "stereo", then plays worn out plastic records, or noisy tape
through it all.
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