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From: | Paul Theodoropoulos |
Subject: | Re: NTPsec reports excessive jitter from GPSD/KPPS SHM |
Date: | Tue, 10 Mar 2020 13:52:59 -0700 |
User-agent: | Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:68.0) Gecko/20100101 Thunderbird/68.5.0 |
Hi Paul, Gary.
So moving the GPS to the end of the file AND keeping noselect is redundant?
For my application, I'll always prefer GPS time if it's available, so removing noselect and moving it to the end is what I want?
-Nick
------ Original Message ------
From: "Gary E. Miller" <address@hidden>
To: "Paul Theodoropoulos via" <address@hidden>
Sent: 3/10/2020 11:56:46 AM
Subject: Re: NTPsec reports excessive jitter from GPSD/KPPS SHM
Yo Paul!
On Tue, 10 Mar 2020 11:52:45 -0700
Paul Theodoropoulos via <address@hidden> wrote:
On 3/10/20 11:40, Gary E. Miller wrote:
> Yo Nick!
>
> On Tue, 10 Mar 2020 18:15:27 +0000
> "Nick Burkitt" <address@hidden> wrote:
>
>> I think it's time to stick a fork in this one.
> Almost. A few things still hanging.
>
> You still have this near the top of your ntp.conf:
>
> # GPS Serial data reference (NTP0)
> refclock shm unit 0 refid GPS noselect
>
> It should be after all your other time sources.
Question - if the GPS refclock is noselect, shouldn't that mitigate
the necessity to have it at the bottom of the list?
Yeah, mostly, but many people do not want the GPS refclock to be
noselect.
For example, if you have a power outage, and on reboot your net is
still down, then the PPS can not work without another chimer with valid
seconds. So your NTP can not get a time. The GPS can provide the base
seconds, so avoiding that trap.
RGDS
GARY
---------------------------------------------------------------------------
Gary E. Miller Rellim 109 NW Wilmington Ave., Suite E, Bend, OR 97703
address@hidden Tel:+1 541 382 8588
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"If you can't measure it, you can't improve it." - Lord Kelvin
-- Paul Theodoropoulos www.anastrophe.com
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