[time-nuts] 58503A alarm light on

Bob Camp kb8tq at n1k.org
Sat Apr 4 16:53:23 EDT 2015


I’ve seen the same sort of < 1 us holdover estimates out of mine as well. 
I for one do *not* believe that it’s going to do 200 ns holdover in 24 hours, 
even if it seems to think it can ….(yes I’ve pulled the antenna and watched
it drift). 

Given that the objective of the prediction function was to decide if it could 
make 10 us over 24 hours, anything below a few us probably was not worth
arguing about when they did the design. 

In this case, a >11 us estimate says “I’m not going to make it”. That means the 
box is telling you it is not able to do what it should. 


> On Apr 4, 2015, at 1:12 PM, Charles Steinmetz <csteinmetz at yandex.com> wrote:
> Dave wrote:
>> The 9.2 us/initial 24 hrs is a lot worst
>> than it was a few days ago (4.9 us/initial 24 hrs), but 4.9 was unusually
>> low. I have never seen it that low before
> FWIW, mine generally shows 20 to 150 nS of predicted holdover uncertainty for the initial 24 hours.  Leveling off at 5-10uS could indicate a less than optimum antenna signal (if the sky view is good, possible multipath?), or an OCXO that isn't as stable as it should be.
> Best regards,
> Charles
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