kb8tq@n1k.org said: > Well, if you actually sit down and measure the serial timing on a modern GPS > module, you will find that it is very consistent. That degrades quickly if > you enable a few dozen sentences. Sub 10 ms accuracy is not a tough target > to hit when standing still. Do you have brand names/models for units that give good serial timing? (or even reasonable?) All the ones I've tried have ballpark of 100 ms of wander. The short term jitter is in the ms range but the long term wander is more like 100 ms peak-peak. I assume it's a firmware screwup, probably because it didn't get into the requirements sheet. The last time I looked carefully was quite a few years ago. Maybe one of the newer brands is reasonably good. The Garmin 18 was reasonably good. The 18x is crap. I assume they outsourced some of the work rather than updating their old firmware. In case anybody is concerned about the PC end of serial timing, I have good data from a Z3801A feeding Linux. With ntpd's filtering, it's well under a ms. -- These are my opinions. I hate spam.

Hi From what I have seen, both uBlox and Furuno are very consistent in their serial timing. I’ve looked at a lot of modules, but those two come to mind pretty quick. Bob > On Jul 15, 2016, at 4:50 PM, Hal Murray <hmurray@megapathdsl.net> wrote: > > > kb8tq@n1k.org said: >> Well, if you actually sit down and measure the serial timing on a modern GPS >> module, you will find that it is very consistent. That degrades quickly if >> you enable a few dozen sentences. Sub 10 ms accuracy is not a tough target >> to hit when standing still. > > Do you have brand names/models for units that give good serial timing? (or > even reasonable?) > > All the ones I've tried have ballpark of 100 ms of wander. The short term > jitter is in the ms range but the long term wander is more like 100 ms > peak-peak. I assume it's a firmware screwup, probably because it didn't get > into the requirements sheet. > > The last time I looked carefully was quite a few years ago. Maybe one of the > newer brands is reasonably good. > > The Garmin 18 was reasonably good. The 18x is crap. I assume they > outsourced some of the work rather than updating their old firmware. > > In case anybody is concerned about the PC end of serial timing, I have good > data from a Z3801A feeding Linux. With ntpd's filtering, it's well under a > ms. > > > -- > These are my opinions. I hate spam. > > > > _______________________________________________ > 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.