[time-nuts] 1pps signal presence with no GPS signal.

David Kirkby david.kirkby at onetel.net
Thu Jul 7 18:59:35 EDT 2005

Magnus Danielson wrote:

>>Is turning off the 1pps, the best thing to do if controlling a crystal 
>>or rubidium? It seems most logical to me, so I can't understand why the 
>>default is to not to.
> Turning of the internal PPS is a crude way to say "no signal" compared to
> having it read of the GPS kit. Also, if it is not turned on normally, then the
> design might not be done for it either. So, it boils down to how your locking
> scheme works. For some very simple schemes, loosing the PPS is worse than the
> wrong PPS.
> Cheers,
> Magnus

I take the point made by yourself and others that whether to turn on or 
off the 1pps is better depends on what you are syncing to and how the 
syncing is done.

In my case, I intend locking two items to 1pps.

a) PRS10 rubidium from Stanford.

b) HP 10811A via the Bruce Shera board.

As far as I can tell, the PRS10 will not update the rubidium's frequency 
unless the 1pps is present, so it would seem to me the PRS10 would 
benefit from no 1pps signal rather than the wrong one. But perhaps I am 

In the case of a 10811A via the Shera board, I am less sure.

David Kirkby,

Please check out http://www.g8wrb.org/
of if you live in Essex http://www.southminster-branch-line.org.uk/

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