[time-nuts] Introduction & GPSDO Question

Tim Lister listertim at gmail.com
Thu Apr 19 23:00:44 EDT 2018

On Thu, Apr 19, 2018 at 1:47 PM, Tom Koza <wb6fyr at gmail.com> wrote:
> Hello Everyone,
> My name is Tom and my amateur callsign is WB6FYR, I'm a newcomer to this
> group.
> I'm mainly interested in creating a reasonable 10mHz standard for my
> various pieces of test equipment here at home.  To that end I've purchased
> and received an Ebay "Trimble Inside" GPSDO unit, described as model
> 57963.  No instructions or manual were included with the hardware.
> The unit has now been powered up for the past 18 hours with the GPS antenna
> connected with a favorable outside view of the southern sky.  I am however
> uncertain if the hardware is GPS locked based on the two external ACT
> status LEDs, the leftmost LED is solid yellow and the adjacent right LED is
> rapidly flashing red.  The 1pps LED is flashing once per second as expected.

Welcome Tom. This unit sounds very similar to the green-fronted BG7TBL device
that I have and which seem to be popular on ebay etc right now. As
Bryan suggested,
your best bet is to get a serial cable and get Lady Heather. Assuming
it detects the
unit, a good thing to do is to get the serial terminal up and check
the status. To do
this, do:
!t (this starts terminal emulator mode)
F1 (turns off echo)
If a series of 2 hex digits groups are scrolling by, do:
TOD DI (This DIsables TimeOfDay output)
This should give you a 'UCCM >' prompt. Try:
which will print out the status display which will tell you if it is
tracking the satellites, what the survey location is (it may need a
new survey done)

> Can anyone point me to an online manual or explain the ACT status LEDs and
> how to interpret those indications.

I asked my ebay seller for the manual and eventually got a 4 page PDF
of not very helpful Chinglish, most of which was on configuring the
serial port. It's probably not worth the electrons to send but I can
try and dig it out. There is a good thread on the eevblog forum but
that seems to be down right now. There is a good write up at

One question: did you power the unit on before attaching a decent
outdoor antenna ? I had problems with mine with an indoor patch
antenna (the Trimble is an old GPS receiver, has a small no. of
channels and is not very sensitive compared to a modern unit) and it
would turn most of the lights on after a while and stop working. These
problems went away after I connected on outdoor antenna and
powercycled the unit.


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