[time-nuts] Cheap Rubidium

[Lux, Jim (337C)]

> -----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.