[time-nuts] DATUM GPS Thingies...

[Burt I. Weiner]

There is a master reset in the units that should be done when moving 
the units any considerable distance.  It will eventually find itself 
but takes considerably longer if you don't do the reset.  Without 
doing that it's trying to go by it's last collected almanac.  On my 
units it's a matter of turning the unit off off, flipping a dip 
switch, turning it on and waiting for a message to tell you to turn 
the power off and put the switch back.  After that it will start 
collecting birds within a very few minutes and probably have them all 
within about 15 minutes.

Burt, K6OQK

At 09:00 AM 11/18/2007, you wrote:
>From: "John Miles" <jmiles at pop.net>
>Subject: [time-nuts] Datum 9390 Rb phase noise
>To: "Discussion of precise time and frequency measurement"
>         <time-nuts at febo.com>
>Message-ID: <PKEGJHPHLLBACEOICCBJIEPGCKAB.jmiles at pop.net>
>Content-Type: text/plain; charset="us-ascii"
>
>Well, I bought the other Datum 9390 that was for sale at the time Mike
>posted this message (eBay 260177272556), and it's certainly an impressive
>box of stuff for $150.  There is an Efratom Rb module, a couple of power
>supplies, and a bunch of cards with a wirewrapped(!) back plane.
>
>I hooked up an antenna and it's reporting '1 USABLE SATELLITE' so far, so I
>guess there's not much wrong with it if anything.  The last-known GPS
>location corresponds to "Cavium Networks HQ" in Google Earth, in Mountain
>View, CA.  The rubidium oscillator works and appears to be in calibration.
>
>The only fly in the ointment is the phase noise at the 10 MHz output:
>http://www.thegleam.com/ke5fx/compare.gif
>
>Is -120 dBc/Hz par for the course for Efratom FRS-C rubidium modules, or is
>there likely to be a problem with this one?
>
>-- john, KE5FX

Burt I. Weiner Associates
Broadcast Technical Services
Glendale, California  U.S.A.
biwa at earthlink.net
K6OQK