[time-nuts] Time Nuts at PTTI this past week

Robert Lutwak Lutwak at Alum.mit.edu
Sat Dec 9 16:34:27 UTC 2006


Yes, the older cesiums (5061, 5040, etc.) had an analog adjustment for the 
C-Field, which could push the frequency by a few parts in 10^10.

The modern cesiums (5071, 4040, 4310, etc.) automatically servo the C-Field 
to the atomic spectrum with high accuracy.  They can be digitally tuned via 
RS232 commands with typical resolution of 1e-15.

-RL

p.s. I don't know how y'all are adding up the Time-Nuts and clocks 
represented at PTTI but I was there and I have a hundred or so cesiums and a 
few thousand rubidiums.     :-)


----- Original Message ----- 
From: "Bill Hawkins" <bill at iaxs.net>
To: "'Discussion of precise time and frequency measurement'" 
<time-nuts at febo.com>
Sent: Saturday, December 09, 2006 11:11 AM
Subject: Re: [time-nuts] Time Nuts at PTTI this past week


> Ah, yes, the C field. A change in magnetic field can change
> the clock frequency. Parts in 1e-14 are exceedingly small.
>
> Is it necessary to correct for the Earth's magnetic field
> when the clock travels?
>
> Bill Hawkins
>
> Actually, that's a test that can be done at home with a
> couple of 2-3 foot diameter solenoid coils. Be tough to
> find an ammeter good to 1e-15, though.
>
>
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