[ntp:questions] project ntp.br

François Meyer nobody at nowhere.invalid
Fri Oct 5 11:42:09 UTC 2007


Antonio M. Moreiras <antonio at moreiras.eng.br> wrote:
> Dear Sirs:
> 
> NIC.br is working on the project ntp.br, that has the goal of improving 
> the quality of time synchronization in (brazilian) Internet hosts and 
> networks and of provide legal brazilian time.
> 
> Basically we intend to provide stratum 1 and stratum 2 servers, 
> synchronized with legal brazilian time (that is kept by the observatorio 
> nacional - www.on.br - and is, in last instance, UTC).
> We will have 3 of the following structure (at 3 different sites, at 3
> different cities: Sao Paulo, Rio de Janeiro, Brasilia):
> 
> -----------------------------------------------------------
>  Observatorio Nacional (Cesium clock)
>                 |
>                 |(periodically assures the
>                 | accuracy with the official
>                 | brazilian time - that is
>                 | in last instance UTC)

For real time purposes (as NTP),  formally  this  is
UTC(ONRJ), TA(ONSP) and TA(ONBR)  (just  formal,  no
practical consequences if only NTP is concerned).

>                #
>       ** Rubidium clock **
>         ** Stratum 0 **
>           Symmetrycom

I cant see why you need a Rb clock here if UTC(ONRJ)
(or a slightly degraded version in the case  of  the
secondary observatories) is available locally.

No remark on the structure below stratum 1, but from
a metrological point of view,  in  my  opinion,  the
complete structure could read like this :

    UTC
     |
     |Circular T BIPM
     |
     |
    UTC(ONRJ) ---------------> NTP st 1, id 0 ---> down to lower strata
     |                              |
     |                             peer
     |                              |
     |__________TA(ONSP) ---> NTP st 1, id 1---> down to lower strata
     | GPS link                     |
     |                             peer
     |                              |
     |__________TA(ONBR) ---> NTP st 1, id 2 ---> down to lower strata
       GPS link

-- 
François Meyer




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