[ntp:questions] TXCO derived PPS and Atom PPS Clock Discipline driver

unruh unruh at wormhole.physics.ubc.ca
Tue Oct 19 12:53:37 UTC 2010


On 2010-10-18, Viktar Palstsiuk <viktar.palstsiuk at promwad.com> wrote:
> I added local clock driver to ntp.conf:

NONONONONO Never use the local clock driver. It is useless. It is asking
the clock itself for its time in order to discipline its own time. Makes
no sense. What he meant was that you need another real time source
probably to determine the seconds (PPS only tells you when a second
occurs, not which second it is. )
local clock is there only to provide the illusion that the clock is set IF it is
acting as a server to a bunch of different clocks who want something
that sounds authoritative ( even if it is not ) (half a league, half a
league, half a league forward, into the valley of death rode the six
hundred).

>
> server 127.127.1.0 minpoll 4 maxpoll 4 prefer true
>
> server 127.127.22.0 minpoll 4 maxpoll 4
> fudge 127.127.22.0 flag3 1
>
> The result repeats:
>
> # ntpq -p
>      remote           refid      st t when poll reach   delay   offset  jitter
>==============================================================================
>  LOCAL(0)        .LOCL.           5 l   11   16  377    0.000    0.000   0.008
>  PPS(0)          .PPS.            0 l    -   16    0    0.000    0.000   0.000
>
> On Mon, Oct 18, 2010 at 5:19 PM, G?ran Sandin <gsan.news at mailnull.com> wrote:
>> On 2010-10-18 15:05, Viktar Palstsiuk wrote:
>>>
>>> Hello
>>>
>>> I use TXCO derived PPS. I set date and time manually.
>>> Is it correct to use Atom PPS Clock Discipline driver with ntp.conf like
>>> this:
>>>
>>> server 127.127.22.0 minpoll 4 maxpoll 4 prefer
>>> fudge 127.127.22.0 flag3 1
>>
>>> But still can not get good PPS(0) status in ntpq -p
>>>
>>>
>>> ? ? ?remote ? ? ? ? ? refid ? ? ?st t when poll reach ? delay ? offset
>>> ?jitter
>>>
>>> ==============================================================================
>>> ?PPS(0) ? ? ? ? ?.PPS. ? ? ? ? ? ?0 l ? ?- ? 16 ? ?0 ? ?0.000 ? ?0.000
>>> 0.000
>>
>> Hi Viktar,
>>
>> as far as I understand, you need another source to provide the time as well.
>> "prefer" keyword should be on the other source.
>>
>> Check this page
>> http://www.eecis.udel.edu/~mills/ntp/html/drivers/driver22.html
>>
>> /G?ran
>>
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>>
>>
>
>
>




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