Finally got a chance to grab more stats. my refclock line now looks like this:
refclock SHM 0 refid GPS offset 0.060 delay 0.22 minsamples 64 I'm attaching the latest stats. On Mon, Aug 15, 2016 at 10:18 AM, Bill Unruh <un...@physics.ubc.ca> wrote: > On Mon, 15 Aug 2016, Chris Greenman wrote: > > >> No. We're just fine tuning the refclock line in chrony.conf. I don't >> really >> experience huge jumps. It might fall behind during a reboot because the >> pi doesn't >> have an RTC but rather it saves time on shutdown and restores on boot. >> > > Ah sorry. they yes, during that time period gps settled down to being out > about 10ms > which is well within your requirements. Unrotunately, nmea is not the most > stable of references. Thus if for some reason your gps puck becomes busy > for > some reason, (moving the computer, something happens with the gps > constellation,...) that offset could change, but certainly not by a second. > The handling of leap seconds by your puck could be an issue. Not sure how > it > handles that. But at worst it would mean that some midnight (UTC) at the > end > of Dec or Jun, the clock would suddenly be out by a second, and would > slowly > (well not that slowly with chrony) drift its way back into sync. > > > > >> >> Really my only goal is to have somewhat accurate (less than a second) >> time whether I >> have internet or not. We've already achieved this, now it's just a >> matter of >> making sure GPS doesn't clobber ntp and vice versa. >> > > Not sure what you mean by "ntp". > >> >> >> >> On Aug 14, 2016 7:24 PM, "Bill Unruh" <un...@physics.ubc.ca> wrote: >> Is this supposed to be at a time when your system suddenly looses >> track >> of the >> time and jumps by hours or days? I see nothing in the gps signal >> that >> indicates anything like that. >> >> If it is supposed to be at the begining of this sample, please give >> a >> sample >> which spans across, not begins at, one of those weirdnesses. >> >> Note also that probably a copy of the measurements and the refclock >> logs >> ove >> onw of those times might be more illuminating. Statistics is rather >> processed >> already. >> >> >> >> >> >> >> William G. Unruh __| Canadian Institute for|____ Tel: >> +1(604)822-3273 >> Physics&Astronomy _|___ Advanced Research _|____ Fax: >> +1(604)822-5324 >> UBC, Vancouver,BC _|_ Program in Cosmology |____ >> un...@physics.ubc.ca >> Canada V6T 1Z1 ____|____ and Gravity ______|_ >> www.theory.physics.ubc.ca/ >> >> On Sun, 14 Aug 2016, Chris Greenman wrote: >> >> Ok I grabbed a sample of the clock statistics. >> >> >> On Fri, Aug 12, 2016 at 2:53 PM, Bill Unruh >> <un...@physics.ubc.ca> wrote: >> On Fri, 12 Aug 2016, Chris Greenman wrote: >> >> it's a usb puck. so no. Actually I haven't >> actually looked but >> typical USB is +5v data+ data- and gnd. As >> far as I know the only place the pps signal is >> available is inside the >> puck between the GPS module and the usb >> interface. >> >> >> Well, usb serial immitatiors can also immitate the >> control lines from a serial >> line. Thus one of the usb packets can be a simlation >> of the PPS signalalong >> the appropriate serial line. But those are likely to >> have far worse behaviour >> than the actual lines. >> It might however be better than the data phrases >> usually coming along the >> serial line. >> >> >> >> like I said I COULD crack it open and run a new >> cable that included >> the pps line. >> >> On Fri, Aug 12, 2016 at 2:24 PM, Bill Unruh >> <un...@physics.ubc.ca> >> wrote: >> >> >> William G. Unruh __| Canadian Institute >> for|____ Tel: >> +1(604)822-3273 >> Physics&Astronomy _|___ Advanced Research >> _|____ Fax: >> +1(604)822-5324 >> UBC, Vancouver,BC _|_ Program in Cosmology >> |____ >> un...@physics.ubc.ca >> Canada V6T 1Z1 ____|____ and Gravity >> ______|_ >> www.theory.physics.ubc.ca/ >> >> On Fri, 12 Aug 2016, Chris Greenman wrote: >> >> I CAN hook it up for PPS but it will >> require cracking open >> the puck and it's not that >> crucial for my use >> anyway. >> >> >> Isn't there an output line from the puck >> which carries the PPS >> signal? >> >> >> >> >> >> >>
statistics.log.tmp
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