[ntp:questions] Re: isolated network + accuracy

Richard B. Gilbert rgilbert88 at comcast.net
Mon Dec 13 15:52:21 UTC 2004


Alaios wrote:

>Goof morning. I have an isolated network and i want to
>achieve accuracy smaller than 1ms. Do u know if that
>is possible? How i must configure the clients for
>that?
>Any suggestion?
>
>
>		
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Without a stable source of time, I'd say that synchronization within 1ms 
is not possible.  The typical, unsynchronized, computer clock is neither 
stable nor accurate.

You will need a hardware reference clock of some sort.   A cesium 
frequency standard (with clock option) is the best there is.  It's also 
extremely expensive.  A rubidium standard is second best and 
considerably cheaper but still expensive to buy and maintain.  A GPS 
timing receiver can be obtained for less than $500 US and is a very good 
choice if you can place an antenna where it has an unobstructed view of 
the entire sky.  An oven controlled quartz crystal oscillator can 
provide a stable source.

Configure one computer with attached hardware reference clock as the 
server.   Configure the clients to get their time from the server.

Don't expect much from Microsoft Windows in the way of accuracy; the 
clock resolution is too low and the operating system tends to lose 
interrupts (clock ticks) when it is busy doing something else.  Linux 
also has been known to have problems with losing interrupts.



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