[time-nuts] Effect of medium term loss of GPS or power

David Kirkby david.kirkby at onetel.net
Sun Jun 5 01:40:30 EDT 2005

What is the effect of a medium term loss of

a) GPS signal on a GPS locked source?
b) Power loss to a GPS locked source?

By 'medium term', I am meaning 30 minutes to 1 hour?

I will be locking two sources:

1) PRS10 Rubidium from Stanford

2) 10811A or 10811-60111 using the Brooks Shera board.

and are considering doing some comparisons with someone perhaps about 
half an hour to an hours drive away with his GPS locked source.

I could keep power on my sources, but not keep a GPS (certainly not in 
position mode anyway!).

I assume if *power* is removed from the Brook Shera design, it would 
suffer badly, as there would be no record of the last ADC voltage and 
you would expect to wait about 5x the time constant for the DAC voltage 
to get back close to the correct value.

In contrast, *power* outages with the PRS10 would not be such as issue, 
as the last DAC voltage will be stored in EPROM.

Obviously the rubidium should keep more stable than a crystal if power 
is removed, but I'm more interested in the effect on the phase locking 
systems, than of the actual sources themselves.

Soon I should be in a position to measure these effects myself, which is 
obviously the best way. But I suspect others have done these sorts of 
tests and I'd be interested in what they observed.

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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