[time-nuts] need recomendation for a portable 10mhz reference oscilator
magnus at rubidium.dyndns.org
Wed Dec 12 05:08:42 EST 2007
From: bg <bg at lysator.liu.se>
Subject: Re: [time-nuts] need recomendation for a portable 10mhz reference oscilator
Date: Wed, 12 Dec 2007 06:58:15 +0100
Message-ID: <1197439095.11811.3.camel at bg-desktop>
> On Tue, 2007-12-11 at 18:38 -0500, John Ackermann N8UR wrote:
> > To get decent (for some definition of "decent") timing, you need to
> > operate the receiver in "0-D" mode, telling it where it is and letting
> > it solve just for time. I haven't done the experiments myself but I
> > believe that the time accuracy is pretty dramatically degraded when
> > operating in 2-D or 3-D mode.
> > > How long does a survey take (in good conditions) and what sort of time
> > > constant would you want to use with a navigation box?
> > It depends on the receiver, but usually it's a few hours to a full day.
> > Of course, if you use external software you can use whatever time
> > period you want.
> > John
> I am surprised surveying mode is needed anymore. In a SA environment it
> makes sense, but for me its hard to understand with the current accuracy
> given by the GPS system.
For the 2,13E-9 precission needed, very simple arrangements should be needed
around a standard GPS receiver. No fancy features like sawtooth correction and
TRAIM needed. My little bluetooth-GPS would do after a very mild modification
If you use a OSA 8712 together with a simple GPS, only very simple control
should be needed. Powerbudget and price could be held fairly low.
The optimum design does not always relate to optimum Allan Deviation curve you
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