[LinuxPPS] Ultimate time server

[Javier Herrero]

El 29/12/2010 09:52, Cirilo Bernardo escribió:
>
> It is instability (short term error, a contributor to jitter) really
> rather than drift (long term error); the instability is due to
> increased noise as the tube ages. It is rubidium vapor which is used
> and the radio frequency is locked to an absorption line of Rb. A
> number of techniques can be employed and the specific technique chosen
> will determine the jitter - so even 2 Rb clocks can have slightly
> different characteristics.   As the tube ages you will typically have
> an increasing metal deposit on the tube (and also less Rb vapor in the
> tube) which in turn means poorer signal on the radio detector and
> poorer control of the signal locking.
>
Not only that, Rb clocks have also drift, due to several reasons (helium 
permeation in the tube has been analized as one of them, this paper 
talks abut it, and also about other causes: 
http://www.dtic.mil/cgi-bin/GetTRDoc?Location=U2&doc=GetTRDoc.pdf&AD=ADA485423 
)

Regards,

Javier