[time-nuts] LPRO-101 with Brooks Shera's GPS locking circuit

[Magnus Danielson]

From: "Poul-Henning Kamp" <phk at phk.freebsd.dk>
Subject: Re: [time-nuts] LPRO-101 with Brooks Shera's GPS locking circuit 
Date: Sat, 16 Dec 2006 17:06:00 +0000
Message-ID: <29410.1166288760 at critter.freebsd.dk>

> In message <20061216.171802.-1808230165.cfmd at bredband.net>, Magnus Danielson writes:
> 
> >> The way you do this is by measuring the ADEV between your two sources
> >> and how it changes with changes in your timeconstant.
> >
> >I.e. out of your TIC. The trouble is that you do not get one result but
> >several. Either you just drive the time-constant to minimize ADEC(100) or
> >something or you are a little more creative and make a (possibly weighted)
> >sum of a few ADEVs (say 10, 30, 100, 300 and 1000) and then let that be the
> >parameter to be minimized. Maybe an integral over ADEV to integrate the
> >energy would be appropriate, maybe not.
> 
> No, that is too simple.
> 
> Both OCXO and Rb units have the same basic ADEV shape and all
> GPS receivers have the same basic ADEV curve and the combined
> ADEV curve has a limited range of shapes.  All you need to do
> is monitor the shape and you know if your timeconstant is too
> short or too long.

Hmm, yes indeed. Also recall that the GPS receiver and TIC have similar ADEV
shapes.

You still want to produce some form of quality measure for the ADEV shape in
order to form some form of control loop. It needs to be articulated.

Cheers,
Magnus