Re[2]: NTPsec reports excessive jitter from GPSD/KPPS SHM

[Nick Burkitt]

Hi Gary.

I think it's time to stick a fork in this one.

In summary, the issue was that my ntp.conf settings for the GPS and PPS shared memory units did not match the device declarations on the gpsd command line. This was exacerbated by ordering those devices' on the command line in a non-standard way.

ntpmon numbers seem much more reasonable now:

remote  refid st t when poll reach delay   offset   jitter
*SHM(2) .PPS.  0 l    2    8  377    0ns -10.37us  7.337us
 SHM(0) .GPS.  0 l   60   64  377    0ns -60.73ms 6.4122ms

I've uploaded a 1/2 day's ntpviz stats to https://drive.google.com/open?id=1YXOxaQq94zurABpwtocW3gbpSDPSW5dO. Configuration details are in ntp.txt, graphs in ntpgraphs/. The drift file was inaccessible for most of the period due to incorrect ownership, so it was only updated once.

Thank you for your help. I greatly appreciate the time and effort you put into this discussion, and all the other discussions on the list. I can't imagine getting this kind of access to a principal developer for a commercial product.

Thanks again,

-Nick

------ Original Message ------

From: "Gary E. Miller" <address@hidden>

To: address@hidden

Sent: 3/9/2020 12:27:10 PM

Subject: Re: NTPsec reports excessive jitter from GPSD/KPPS SHM

Yo Nick!

 

On Mon, 09 Mar 2020 19:01:48 +0000

"Nick Burkitt" <address@hidden> wrote:

 

No problem, but let's get back in sync. Here's the info again. This

configuration seems to be working. Am I mistaken?

 

Looking better. But my previous comments still stand. SHM(0) should

be last in the file, not first. SHM(2) should be first in the file.

And you have never provided the value in your drift file, or ntpviz

stats.

 

RGDS

GARY

---------------------------------------------------------------------------

Gary E. Miller Rellim 109 NW Wilmington Ave., Suite E, Bend, OR 97703

address@hidden Tel:+1 541 382 8588

 

Veritas liberabit vos. -- Quid est veritas?

"If you can't measure it, you can't improve it." - Lord Kelvin