Dear Bob ( I shouldn't write email while walking around doing the housework!)
The possibility of other constellations causing a problem was one of the things I checked, running it in GPS only mode. No improvement. Cheers Michael On Wednesday, 20 April 2016, Bob Camp <[email protected]> wrote: > Hi > > Actually there is one other possibility: > > If you have more than one “system” enabled *and* it’s doing “all in view” > *and* it’s applying that > to the timing *and* the population in view changes significantly … (whew !) > > As the solution pops between GPS and Glonass, you will get a time shift. > Since it’s a “which one > is right?” sort of thing … Trimble probably does not want to get into the > debate. They would love > to sell stuff to everybody. > > Bob > > > > On Apr 19, 2016, at 3:32 PM, Logan Cummings <[email protected] > <javascript:;>> wrote: > > > > Hi Michael, Bob, > > > > I had been very curious about this myself - the new ICM SMT 360 > > modules at first glance seem like a great deal - < $50 and 10MHz TCXO > > disciplining built right in. > > > > I came across this paper which compares the older (GPS-only) ICM SMT > > to a LEA-6T - the Trimble fares poorly in their testing. The graphs > don't > > show an issue quite like yours Michael, so I'd be curious about the line > of > > questioning Bob brings up, how many satellites are being used by the > > receiver - say in GPS-only mode? > > > > http://www.imeko.org/publications/tc10-2013/IMEKO-TC10-2013-028.pdf > > > > Does anyone else have comparative experience with the new SMT modules > > from Trimble? RES or ICM? > > > > Thanks, > > -Logan > > > > On Tue, Apr 19, 2016 at 4:01 AM, Bob Camp <[email protected] <javascript:;>> > 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 < > [email protected] <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 -- [email protected] <javascript:;> > >>> To unsubscribe, go to > >> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > >>> and follow the instructions there. > >> > >> _______________________________________________ > >> time-nuts mailing list -- [email protected] <javascript:;> > >> To unsubscribe, go to > >> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > >> and follow the instructions there. > >> > > _______________________________________________ > > time-nuts mailing list -- [email protected] <javascript:;> > > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > > and follow the instructions there. > > _______________________________________________ > time-nuts mailing list -- [email protected] <javascript:;> > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. > _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
