Hal Murray <hmur...@megapathdsl.net>:
>
> >> How many of the NMEA devices have GPS rollover problems?
> >> (either now or soon)
>
> > It's impossible to tell. When a device will roll over is, because of the
> > pivot-date trick, not a function of its hardware type but of its firmware
> > release. --
>
> Are there any known examples?
We had a tracker issue relating to this on an OnCore GT. I think the
submitter promised a patch, but it hasn't landed.
I'm pretty sure I've seen one or two descriptions of people coping
with rollovers on time-nuts while chasing possible sources for old
refclock types.
It's not exactly a *common* problem - most people who buy consumer-grade
GPSes don't seem to keep them in service that long.
I've never seen it myself. I have one device that might be old enough -
one of the original DeLorme Earthmates from the eatly nineties - but I haven't
powered it up in a *long* time; not sure it still works.
> I have a collection of NMEA toys. I don't remember seeing GPS rollover on
> any of them. Some of them are quite old, but I don't think any have reached
> 20 years yet.
Right. You'd have to watch for 19.2 years after you acquired the device to be
*sure* of seeing it roll over.
> We could test fixup software by setting the system clock ahead far enough to
> look like GPS had rolled over.
What kind of fixup? I looked long and hard at this problem in the
context of GPSD. I never found one that wasn't as bad - or worse -
than relying on the sysrem clock date.
--
<a href="http://www.catb.org/~esr/";>Eric S. Raymond</a>
Please consider contributing to my Patreon page at https://www.patreon.com/esr
so I can keep the invisible wheels of the Internet turning. Give generously -
the civilization you save might be your own.
_______________________________________________
devel mailing list
devel@ntpsec.org
http://lists.ntpsec.org/mailman/listinfo/devel
