ntpsec is ignoring PPS

Chris Caudle 6807.chris at pop.powweb.com
Tue Nov 30 20:29:34 UTC 2021


On Tue, November 30, 2021 12:37 pm, folkert via users wrote:
> ntpq shows:
>
> root at gpsdomonitor:~# ntpq -c pe -n
>      remote           refid      st t when poll reach   delay   offset
> jitter
> oPPS(0)          .PPS.            0 l   12   16  377   0.0000  -0.0114  
0.0040
> xPPS(1)          .PPS.            0 l    1    2  377   0.0000 490.4861  
0.0065
>  nl.pool.ntp.org .POOL.          16 p    -   64    0   0.0000   0.0000
> 0.0019

What are the units of offset?  Is it just that PPS1 is offset so much it
is flagged as a bad clock?  Especially if it is considered a stratum 0
clock it should not be that far off.


> PPS(0) is a regular garmin lvc18, while PPS(1) is a GPS disciplined
> osc...that is divided to 1PPS using a "picdiv"

Are you using PD11 and synchronizing to a known good PPS to get the output
synchronized to true top-of-second?  If you just divide 10MHz down to 1Hz
you will get some random offset up to +/-500ms from the true top of
second.

-- 
Chris Caudle







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