[time-nuts] Quick Allan deviation measures

[Magnus Danielson]

From: "Tom Van Baak" <tvb at leapsecond.com>
Subject: Re: [time-nuts] Quick Allan deviation measures
Date: Mon, 24 Jul 2006 12:59:48 -0700
Message-ID: <005501c6af5b$b967a520$790ff204 at computer>

> > See how the GPS diciplined 10811 with extra oven keeps it track above that
> of
> > a normal 10811 sitting in a unit. Notice also that the Cx1 had been
> powered
> > only for an hour instead of over 24 hours.
> 
> Since you're only looking at tau of 0.001 to 1 second
> things like warm-up time and ovens have little or no
> effect.

Just heated, it show of like hell at 100 ms and 1 s. But that quites down quite
quickly. I just wanted to make the point that it was not to be suspected as
being a main part of the noise.

> > Infact, the GPS is worst of all these sources!!!
> >
> > I am quite sure that a 10 s measure would should the GPS even more
> > infavourable.
> 
> Correct (as it should) and even worse at 100 s and maybe
> even 1000 s. But beyond an hour of averaging time your
> Z3801A will start to shine.

It does track, but it tracks badly. Infact, it tracks so badly that it goes
out of lock regularly!!! That when there is 5-6 sats being tracked and even a
bunch more visible above my 10 degrees.

> See typical Z3801A ADEV plot:
> 
> http://www.leapsecond.com/museum/z3801a/log8286v.gif

I suspect mine to be worse. If I where to make a similar measurement I would
have to do some automation that I haven't time.

I have got a few good advices and hints about what may be wrong. Measuring the
clock with the EFC unhooked and grounded is one of my approaches that is
comming right up.

Cheers,
Magnus