Re: [chrony-users] PPS correction not being applied

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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
Canada V6T 1Z1 ____|____ and Gravity ______|_ www.theory.physics.ubc.ca/

On Fri, 24 Feb 2017, Brian Gieryk wrote:


Ok, there is one GPS (with PPS out on a second output, going to GPIO 18 on the rpi)

I did a little change (commented out the two NMEA sources.

I am running gpsd for the GPS source.

It is a Dragino LoRaWAN/GPS hat.

As I mentioned, the GPS is functioning (what appears to me) correctly.

I will add refclocks logging right now.

I will most likely add a second GPS, or more probably, tie it into my Rubidium standard.

As for the PPS signal, ppstest /dev/pps0 give the expected output, finds the PPS signal, and is happy with it.

Chronyc sources just does not seem to recognize it.


No, the problem probably is that PPS only gives time to the second and gives
no idea which second it is. Ie, it is time%1sec. It needs something else and
it needs to know that that something else is actually already working to give
the time with an accuaracy of a bit better than a second. In your case you
told the pps to use nmea, and nmea was not working at all, so the PPS had
nothing to use to tell it which second it was. Lichvar gave you some suggestions. You might try them. 




Thank you!

Brian

Sent from my iPhone


On Feb 24, 2017, at 00:43, Bill Unruh <unruh@xxxxxxxxxxxxxx> wrote:

On Thu, 23 Feb 2017, Brian Gieryk wrote:

I apologize for my seeming ignorance, I have been trying everything I could find in the archives here.


No problem. JUst remember that we have no information about your system except
what you tell us.




I have been using Linux for a grand total of one week, so some patience will be much appreciated.

My Pi does not seem to send email directly to anyone other than myself, so it is a 2 step process to send anything from it.

As for locking to the GPS, the time/date are being set correctly from it now, I would just like some redundancy, and a tad more accuracy, if it can be had.


But I am a bit confused. Do you have two or 3 GPS receivers attached to
your Pi? Or are all of GPS, the two NMEA and PPS coming (as I suspect) from one GPS receiver. If my suspicion is true, then that is not redundancy.
The various attempts t read 3 different times from the same receiver could
actually make things worse, not better (the readings fighting with each other).

Secondly try to get one thing going at a time. GPS, whatever it is (what
reports the gps to the SHM?-- are you using gpsd?) seems to work now. THe NMEA
are not. Use what works to gine the PPS its seconds-resolution, so PPS can
deliver its soperior accuracy, and so you can see if you can get it working.
Worry about redundancy later.



I will get more info shortly.

Thank you for your understanding.

Brian

Sent from my iPhone


On Feb 23, 2017, at 17:46, Bill Unruh <unruh@xxxxxxxxxxxxxx> wrote:



On Thu, 23 Feb 2017, Brian Gieryk wrote:


Relevant chrony.conf snipet:

You do not know what is relevant do you?



# offline sources

refclock SHM 0 refid GPS precision 1e-1


What is putting this info into shm?


refclock SHM 1 refid NMEA precision 1e-9
refclock SOCK /tmp/chrony.ttyS0.sock refid NMEA


Two different sources with the same name. That could cause confusion. Where do these come from?



refclock PPS /dev/pps0 poll 0 refid PPS lock NMEA

Sources output:

pi@raspberrypi:~ $ sudo chronyc sources
210 Number of sources = 5
MS Name/IP address         Stratum Poll Reach LastRx Last
sample
===============================================================================
#* GPS                       0   4   377 15-+1007us   [-1476us]+/-100ms


GPS reports. So why not lock to it?


#? NMEA                      0   4     0      -+0ns   [   +0ns]+/-  0ns
#? NMEA                      0   4     0      -+0ns   [   +0ns]+/-  0ns


Neither of your nmea sources report so PPS has nothing to lock to.


#? PPS                       0   0     0      -+0ns   [   +0ns]+/-  0ns
^? 2610:20:6f15:15::27       0   8     0      -+0ns   [   +0ns]+/-  0ns


What is this source?



pi@raspberrypi:~ $

I don't see anything unusual(?) in the log...


Do you see anything? Why not give us 10 or 20 lines from the refclock log?




I am not an old hand at this......

Thank you!

Brian





On Feb 23, 2017, at 09:09, Bill Unruh <unruh@xxxxxxxxxxxxxx> wrote:

You tell it to lock to NMEA. Do you actually have an NMEA refclock running?
Ie you might want to show us what your complete chrony.conf is.

Also in your sources, what sources are listed? Ie, what is the complete output of chronyc sources command.

In the logging of the refclock, are there any entries? Do they give you a
clue?



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
Canada V6T 1Z1 ____|____ and Gravity ______|_ www.theory.physics.ubc.ca/


On Thu, 23 Feb 2017, Brian Gieryk wrote:

Good morning.

Running chrony 3.1, raspberry Pi 3 model B with the latest Raspbian Jessie.

Have GPS working to set the clock with no issue.

Have good PPS on /dev/pps0

From searching the archives I have :
refclock PPS /dev/pps0 poll 0 refid PPS lock NMEA

Appended to the end of /etc/chrony/chrony.conf

Running chronyd produces no errors

PPS shows in chronyc sources

However the #? next to PPS never changes (48 hours so far) and there are no corrections.

Any thoughts?

Thank you all!

Brian

Sent from my iPhone
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