|Re: [chrony-users] Setting up Chrony with PPS|
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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 | unruh@xxxxxxxxxxxxxx
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On Thu, 18 Feb 2016, Deven Hickingbotham wrote:
First off, thanks for all of the responses! I'm testing your suggestions as
fast as I can and if I apologize if I don't directly reply to a suggestion.
Does /var/run/chrony.ttyAMA0.sock exist? If not, then it is hard to read
it. Your gpsd does not seem to be writing to SHM0
Yes, it does exist:
pi@gps /var/run $ ls -l *.sock
srwxr-xr-x 1 root root 0 Feb 18 16:23 chrony.ttyAMA0.sock
srw-rw---- 1 root root 0 Feb 18 15:43 dhcpcd.sock
srw-rw-rw- 1 root root 0 Feb 18 15:43 dhcpcd.unpriv.sock
srwxr-xr-x 1 root root 0 Feb 18 16:23 gpsd.sock
OK, not sure what it does
But I don't think it existed before I configured chrony.
I suspect it is a socket that chrony listens to, but there needs to be
something that actually writes to that socket as well.
But I have never used sockets on chrony so have no idea.
I am also concerned that your outside clocks are way off ( hundreds of ms )
and have HUGE variances -- the network, unless you are using smoke
your network, should not be out by a hundred ms. Mind you telling your
that your SHM0 is out by 135ms is probably all wrong, and is part of the
So, I would first suggest that you get rid of the nmea, and just use the
external clocks as your reference. and get PPS working. Then you can
get nmea working. One thing at a time.
After removing the refclock references from chrony.conf I get:
pi@gps ~/SystemFiles $ chronyc sources
210 Number of sources = 4
MS Name/IP address Stratum Poll LastRx Last sample
^+ gopher.fart.website 3 7 43 +16ms[ +14ms] +/- 89ms
^? mirror 3 7 41 +17ms[ +17ms] +/- 134ms
^~ com1243.eecs.utk.edu 16 6 59 +71ms[ +55ms] +/- 55ms
^* tock.usshc.com 1 6 59 +15ms[ -696us] +/- 122ms
Is this more in line with what you expected?
Nope. Those are huge uncertainties for network timing. 134ms uncertainty
corresponds to light travel time around the earth uncertainty. I would expect
more like +- 100 microseconds, not milliseconds.
What is your network link?
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