fallback pps source

[Folkert van Heusden]

>> I've got a simple ntp monitoring setup (for hobby). The monitoring
>> computer has a timing gps connected. All works fine. I wonder: is it
>> possible to configure a second pps source that is ONLY used when the
>> primary pps source is not ticking? Thus not selected by how good a
>> source is compared to others, but if it is reachable. That is with
>> the idea that the timing gps (pps) always keeps best time but it may
>> become unavailable for reasons.
> 
> You could make your primary PPS as "prefer".  Then other sources only
> get uses when it is down or obviously crazy.

Oh indeed!
That will work of course. Thanks!