[time-nuts] Cheap Rubidium

Bob Camp lists at cq.nu
Wed Dec 23 22:31:22 UTC 2009


Hi

At least at the 1 second point, I believe that the main issue with getting an order of magnitude better than the 3x10^-13 point is the lack of funding for a decent crystal package for 25+ mm diameter  blanks. 

I doubt I'm going to solve that one in the basement ....

Bob

 
On Dec 23, 2009, at 3:17 PM, Lux, Jim (337C) wrote:

> 
>> -----Original Message-----
>> From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On Behalf Of Bob Camp
>> Sent: Wednesday, December 23, 2009 9:52 AM
>> To: 'Discussion of precise time and frequency measurement'
>> Subject: Re: [time-nuts] Cheap Rubidium
>> 
>> Hi
>> 
>> If you can achieve <= 1x10^-13 at 10,000 to 100,000 seconds, that's quite a
>> bit better than any OCXO has a right to be doing. Yes I know that there is
>> one in the entire universe that gets close.
>> 
>> Even if you just do < 1x10^-12 at 1,000 seconds, that's better than a whole
>> lot of OCXO's will do at that tau.
>> 
>> The place where the OCXO does come in is < 100 seconds. Between 1 and 100
>> seconds you can get a number of OCXO's that will run <2x10^-12 over the
>> entire range. You can fine a lot more that will do < 1x10-12 over that range
>> than you can find that will do < 1x10^-12 at 1,000 seconds. The rubidium is
>> struggling to get to 1x10^-11 at 1 second and may or may not get to 1x10^-12
>> at 100 seconds.
>> 
> 
> 
> Typical (Cassini, MGS, etc., data from Sami Asmar) UltraStableOscillator (USO) specs as used in spaceflight do about 1E-13 at tau =10 to 1000 seconds, 3E-13 at 1 second.  Today, you can probably do maybe an order of magnitude better.  These are state of the art oscillators in a vacuum envelope with double ovens, etc.
> 
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