[time-nuts] GPS noise reduction

Magnus Danielson magnus at rubidium.dyndns.org
Sun Apr 6 06:45:22 EDT 2008

From: "Richard H McCorkle" <mccorkle at ptialaska.net>
Subject: [time-nuts] GPS noise reduction
Date: Sat, 5 Apr 2008 13:20:56 -0800 (AKDT)
Message-ID: <24415. at mymail.acsalaska.net>


> Hello,
> I looked at the dual standard data from yesterdays run, and
> once again the predominance of the short-term variations in
> phase occur simultaneously in both systems. As pointed out
> earlier a 3-corner hat is the wrong methodology as what I
> am doing is closer to a common view comparison.

You missed the point then. The 3-corner hat is indeed a useable methodology,
but you where not doing the measurements to acheive a 3-corner hat, so you
can't analyze it like one.

The common-view meaurement you are doing allows you to use the common reference
(the GPS) as a transfer standard such that you can compare A and B with each
other. The sad thing is that this is not very useful to you.

> If I relax
> my goal to just attempting to reduce the GPS variations that
> are common to both data sets is there any way this can be
> accomplished without adverse effects on the long-term
> stability?
> When I flip between the charted data between the standards
> there are small variations unique to each standard but the
> GPS variations common to both data sets are 10 to 100 times
> larger than the unique variations. It would seem logical
> that some approach could be used with multiple oscillators
> disciplined to a common receiver to reduce the common data
> variations so the unique data would become more predominant.
> Would going to a triple oscillator design allow prediction
> of the common variations?

Adding another oscillator is adding another noise-source. The trouble you have
is that you add too little measurements for each oscillator you add. In this
case, three noise sources needs three measurements.

Once you have your complete three-corner hat, you can solve noises for each
member and then add additional oscillators comparing only to one of the
members in the three-corner hat since you now compare a known noise source with
one unknown and that only takes one measure.


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