[time-nuts] Frequency reference
alan.melia at btinternet.com
Sun Apr 20 19:43:43 EDT 2008
It does not matter how many references you build you will never know how
good they are. There can only one judgement "goodness", and this is
comparison with the national standard. You reference may even be "better"
that a national standard but must be judged against the national standard.
Most countries provided a certification scheme for your reference but you
will pay a lot of money for that, else you use one of the distributed
national standards and then you must know the degradation in the
distribution system which is normally made available. There are several NIST
(NPL in the UK) monographs I believe....surely that is the place to start.
----- Original Message -----
From: "Attila Kinali" <attila at kinali.ch>
To: "Jim Lux" <james.p.lux at jpl.nasa.gov>
Cc: "Discussion of precise time and frequency measurement"
<time-nuts at febo.com>
Sent: Monday, April 21, 2008 12:23 AM
Subject: Re: [time-nuts] Frequency reference
> On Sun, 20 Apr 2008 09:25:37 -0700
> Jim Lux <james.p.lux at jpl.nasa.gov> wrote:
> > > Stupid question, but if one builds his on frequency
> > > reference, how can you be sure it's acurate and precise?
> > not a stupid question at all..PhD dissertations have been written
> > about answering it.
> If there are dissertations written on this, are there any
> good ones to read?
> > > Or to but it in other words: how do you measure self build
> > > devices?
> > Build 2 or 3, and compare them against each other. (can't have too
> > many frequency and time standards...<grin>)
> Well.. then you have to build multiple frequency sources
> that exhibit different physical behaviour, otherwise
> slight changes in the enviroment that degrate your
> precision will go unnoticed (ie, if all sources have
> the same temperature coefficient then temperature
> changes will affect all of them the same way making
> you unable to measure this effect)
> > or, take it to somewhere that has a higher quality standard and compare
> Which is quite difficult if you don't have access to a physics
> lab which you can use for a few days to weeks.
> > or, just trust that the performance is inherent in the design, and if
> > it works at all, it's good enough. Typically, if you are building a
> > copy of a known good design, this is a good start.
> I'm an engineer, i don't trust anything i cannot measure,
> because i know that errors and mistakes are inherent in any design :-)
> Attila Kinali
> The true CS students do not need to know how to program.
> They learn how to abstract the process of programming to
> the point of making programmers obsolete.
> -- Jabber in #holo
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