[sdiy] pro EQs

[Magnus Danielson]

From: "Colin f" <colin at colinfraser.com>
Subject: RE: [sdiy] pro EQs
Date: Fri, 31 Dec 2004 18:31:34 -0000
Message-ID: <20041231183131.864CF2543B5 at smtp.nildram.co.uk>

> 
> > I do tend to think of this list as more a place where people 
> > discuss the 
> > restoration of antiques and the building of copies of 
> > antiques. This is 
> > fine if you want an authentic grandfather clock in your hall, 
> > but some of 
> > us do occasionally wonder what the audio equivalent of a GPS 
> > satellite 
> > network with built-in relativistic corrections would look and 
> > sound like.
> 
> Don't those modern atomic GPS timesources lack the fuzzy warmth of sidereal
> time ? ;-)

Not entierly! UTC is being phase-corrected to track the actual time of the
earth +/- 0.9 s but inbetween there is follows the TAI time. The time
difference between UTC and TAI has been corrected with 32 leapseconds but been
quite stable. We will not celibrate a leapsecond this newyearseve, if you ever
wondered.

Many thinks that GPS clocks are "quite" and "stable". That *really* depends.
Most of them are not, and most of them depends on a fair amount of atmosferic
prediction. Long-term tracking is good, but the short and mid term noise can be
rather large.

BTW, the time difference between UT1 and UTC jumped 150 us between the 26th and
27th according to the continous measurements being done. This was being
predicted by early simulations but now have measurements confirmed this.

Cheers,
Magnus