[ntp:questions] Stick to PPS, even if the prefer server fails

Rob nomail at example.com
Sun Mar 29 14:57:17 UTC 2009

alkopedia at googlemail.com <alkopedia at googlemail.com> wrote:
> On Mar 29, 5:12 am, mi... at udel.edu (David Mills) wrote:
>> John,
>> The intended design to detect and suppress bad reference/PPS clocks is
>> at least two additional sources, that do not have to be reference
>> clocks. If the reference/PPS clock sails to the sunset, the selection
>> algorithm will vote it off and the PPS will follow.
> In my case I would trust my PPS signal much more than any other
> source. Why should I run a caesium frequency normal and not trust it?

The point is that a PPS signal by itself does not provide any information
about its reliability.  PPS signals sent by GPS receivers can go
unsynchronized simply because the antenna gets disconnected or covered,
and the receiver will happily send a pulse every second that is drifting
away at a rate determined by the quality of a quartz crystal.

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