[time-nuts] Worst possible error on a rubidium

Jose Camara camaraq1 at quantacorp.com
Fri Jul 15 02:26:08 UTC 2011


A scope with one 10Mhz on two Y channels is enough. Say you get 1 cycle
phase displacement every 15 minutes - that's 1E-10. You can get better than
these 10 digits per 15min by counting divisions per minute or so. Not as
nice as a 12 digits/s counter, but way cheaper...


-----Original Message-----
From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
Behalf Of Dr. David Kirkby
Sent: Thursday, July 14, 2011 1:47 PM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] Worst possible error on a rubidium

On 07/14/11 01:27 PM, Bob Camp wrote:
> Hi
>
> I've looked at a random sample of a couple dozen Rb's that are in the 5 to
> 30 year old range. In about 90% of the cases I'm reasonably certain they
> haven't been adjusted since they left the factory. If they still worked,
> they all came in at or below +/- 3x10^-9.
>
> Bob

Thank you.

Of the couple of dozen, how many worked? Clearly if only two worked, the
data is 
not very useful. But if 15 or more worked, then it's interesting. It would
give 
me reasonable confidence the unit is sufficient for my needs without
bothering 
with calibration.

I do have a friend with a GPS locked rubidium. At some point I'll get the
unit 
to him, but I recently sold my HP 5370B to someone on this list (regretting
I 
sold it now!)

I guess a scope would be OK to check for gross errors by one 10 MHz signal
to 
the X input and another to the Y input.


-- 
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