[time-nuts] Newbie questions

Magnus Danielson magnus at rubidium.dyndns.org
Wed Jan 6 17:10:06 UTC 2010


Hi!

Bob Camp wrote:
> Hi
> 
> Ahhh, that jogs a few of the tired old brain cells....
> 
> You can run the gate off of the GPIB input to get all kinds of silly long
> gates. Then you start to get into the cpu overflow issues. Since it's a MSB
> overflow you can usually clean it up in software *if* you know it's
> happening. 

Notice that it is specified to support gate-times up to 10 Ms (10^7 s). 
I would suspect that both the event and time counters is CPU extended.

Maybe I should pull the PROM and do a readout.

> Since the GPIB is simply telling the counter "start about now" and "finish
> it up now" the accuracy of the GPIB timing does not get into the result. The
> counter still uses it's time base as the standard of comparison.

Well, it will cause a variation in gate-time (about 2 ms can be assumed, 
since that is what programmed gate using GA allows) , but since this is 
used for longer gate times it is not significant. If better precission 
is needed, the external arm input shall be used.

Cheers,
Magnus



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