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 <logan.cummi...@gmail.com> 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 <kb...@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 <michaeljwout...@gmail.com> >> 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@febo.com >>> 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@febo.com >> 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@febo.com > 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@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.