[time-nuts] GPS for Nixie Clock

Bob Camp kb8tq at n1k.org
Fri Jul 15 18:18:25 EDT 2016


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. 


> On Jul 15, 2016, at 4:50 PM, Hal Murray <hmurray at megapathdsl.net> wrote:
> kb8tq at 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.
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