[ntp:questions] Re: announce: NTP FAQ v3.8
Ulrich Windl
Ulrich.Windl at RZ.Uni-Regensburg.DE
Wed Jan 26 14:51:28 UTC 2005
"David J Taylor" <david-taylor at invalid.com> writes:
> Ulrich Windl wrote:
> > Alain <alainm at pobox.com> writes:
> >
> >> Some questions:
> >>
> >> - in Section 3.3 it says: "Some of the best clocks available still
> >> have errors of about 1E-8 PPM" Is this really 1E-14 ?
> >
> > 1E-8 Parts per Million are 1E-14 parts. Right?
> >
> > Like 1E-1cm is 1E-3m.
> >
> > Regards,
> > Ulrich
>
> Mixing numbers like that is very confusing. My personal feelings are that
Isn't "PPM" wrong per se? Shouldn't it be micropart (µP)? ;-)
Wo we easily could have milliparts and nanoparts...
> if you use PPM, then the units should be whole numbers: 15 PPM, 2 PPM
> etc, certainly /not/ fractional parts. If you must use fractions, then
> not more than one decimal place - 1.6 PPM, 0.3 PPM If you need to express
> smaller quantities, just stick with scientific notation 1E-12, 1E-14 etc.
> Clarity of communication is very important.
>
> Even better, of course, where you can use superscripts to write 10-12,
> 10-14 (but not in this plain text e-mail!).
OK, I'll try to keep in mind.
Ulrich
>
> Cheers,
> David
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