[time-nuts] Frequency reference
attila at kinali.ch
Sun Apr 20 19:23:38 EDT 2008
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 :-)
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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