[time-nuts] Trimble SMT 360

[Michael Wouters]

Dear Bob,

Sorry, the two plots are identical; it was a drag and drop fumble.

I should have given more detail - "tried many things" included running the
receiver in position hold ( which is the default ) and free run. The
receiver was being logged during operation and always claimed 5 to 10 SVs.
The antenna is roof-mounted with an excellent view of the sky. I tried
multiple antennas just in case, added a bit of gain, tried multiple SMT
360s, compared with other receivers in the lab ( Resolution T, Javad,
Septentrio, VP Oncore) ...

Another thing I didn't mention was that I tried it on a GPS simulator,
except with a position in the Northern hemisphere ( I'm in the South ) and
it worked fine for 12 hours. I wasn't sure what to make of this but decided
to stop spending my time on this because it was really Somebody Else's
Problem to solve.

In the end, I decided to use another receiver for my application ( GPS
common view, for which we'd been using the Resolution T previously ) but
now that that's almost done, I thought I'd have another look at the the SMT
360 problems.

Cheers
Michael

On Tuesday, 19 April 2016, Bob Camp <kb8tq at n1k.org> wrote:

> Hi
>
> The two plots shown appear to be identical. If they are actually two
> different
> runs, the problem repeats very closely.
>
> If the GPS is not in position hold *and* the antenna is less than ideal -
> That’s
> the sort of thing you may see. Essentially it’s got two locations it
> “thinks” are
> correct. Another possibility is a position hold situation with a very low
> satellite count.
> As a single observed satellite goes in and out of multi path, the solution
> goes all over the place.
> Again, you need a challenged antenna for this to happen. Pretty much all
> of this
> would be apparent from the normal messages out of the part.
>
> Bob
>
>
>
> > On Apr 18, 2016, at 10:13 PM, Michael Wouters <michaeljwouters at gmail.com
> <javascript:;>> wrote:
> >
> > Does anyone have  experience with the Trimble SMT 360 ?
> >
> > I bought some of these four or five months after they were released.
> During
> > testing, the 1 pps output evidenced a problem, as shown in the attached
> > plot (the 1 pps is being measured against a Cs  beam standard), which is
> > not sawtooth-corrected. While there are longish periods of nominal
> > operation, the receiver seems to hop between two solutions.  This
> behaviour
> > is well out of specification.
> >
> > When I contacted Trimble support, they said that the firmware in the
> > receivers was very early, and replaced the receivers. However, the
> problem
> > was still evident with the new firmware. Trimble did not respond to
> further
> > emails.
> >
> > I tried many things to isolate the problem, including restricting the
> > receiver to GPS-only but I was unable to make an improvement.
> >
> > I would like to know if anyone else is operating an SMT 360 and if they
> > have seen any similar behaviour.
> >
> > Cheers[image: Inline image 2]
> > Michael[image: Inline image 1]
> > <smt360.png><smt360.png>_______________________________________________
> > time-nuts mailing list -- time-nuts at febo.com <javascript:;>
> > To unsubscribe, go to
> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> > and follow the instructions there.
>
> _______________________________________________
> time-nuts mailing list -- time-nuts at febo.com <javascript:;>
> To unsubscribe, go to
> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.
>