[time-nuts] A readl atomic wristwatch

[SAIDJACK at aol.com]

Guys,
 
there is only one problem: there is just no way they can claim only 1  
second error in a 1000 years unless they also have a GPS receiver for  
calibration in there, which kind of mutes the point as that has been done using  wwvb 
etc. Let's do the math:
 
1/ (1000 * 365 * 24 *3600) = 3.171E-011 average error required over 1000  
years.
 
The CSAC has a thermal spec of +/-0.5ppb for -20C to +70C, meaning 5.6E-012 
 per Degree C sensitivity.
 
So the temperature would have to stay stable within a couple degrees C,  
hardly possible in a wrist watch.

Also, initial CSAC aging is 0.3ppb per month, about 100x worse than  they 
claimed 1000 year per second accuracy. It gets better over time, but still  
around a ppb per year or so of aging is expected, far off from the 0.032ppb  
claim.
 
They did a great job integrating that together, and its novel, but the  
marketing department is off by many orders in magnitude in their accuracy  
claims.
 
I know CSAC applications that would be very happy to get around  0.1 second 
error per year consistently without external re-calibration in a  stable 
environment.
 
bye,
Said
 
 
In a message dated 10/1/2013 15:32:27 Pacific Daylight Time,  
marks at non-stop.com.au writes:

That's  the first time I have seen a practical explanation and working 
example of a  CASC in operation.

Can I say  "Awesome"?


--marki