[time-nuts] The link to the "introduction"

Attila Kinali attila at kinali.ch
Wed Mar 14 15:53:22 UTC 2012


On Wed, 14 Mar 2012 08:10:42 -0700 (PDT)
George Allen <george_gloria99 at yahoo.com> wrote:

> I understand the cartoon at the beginning; but, it will take me
> a very, very long time to understand the concepts of the paper!

Don't worry. There isn't that much magic to it. With a little bit
of technical background you can understand most of the stuff in
a very short time.

The most important "Concept" is that of fractional deviation.
It's expressed in ppm (part per million, 10^-6), ppb (per billion, 10^-9)
or just as a fraction (eg 10^-12). It tells you that if you measure
some value x, you will be +/- x * 10^-9 (in the case of 1ppb) off of
the true x value.

What is important to note here is, that this deviation is dependent
on how large x is. I.e. if you measure 5 units your deviation could
be 1ppb, going up to 100 units, you will get 10ppb. Also note that
knowing some deviation values for some points does not tell you 
much (or anything at all) about the deviation at other values.
In the above example you could guess that the large x is, the higher
the deviation is. But it could actually be that at 200 units, you
get a deviation of 5ppb. To get a better feeling of this, google
for ADEV plots, or go to febo.com or leapsecond.com and have a look
at some of the graphs.

If you get that concept, everything else is just technicalities
or getting better clocks ;-)

Oh.. by the way.. would you mind not to top post? I know it's common
on this mailinglist, but i think it makes the mails harder to read.


			Attila Kinali

-- 
The trouble with you, Shev, is you don't say anything until you've saved
up a whole truckload of damned heavy brick arguments and then you dump
them all out and never look at the bleeding body mangled beneath the heap
		-- Tirin, The Dispossessed, U. Le Guin



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