[ntp:questions] NTP on local networks

Will Shackleford shackle at nist.gov
Wed Aug 1 13:40:14 UTC 2012


I should have provided  a number of additional details.

The lab is an interior lab on the ground floor of a 3 story building 
with no windows.
The work is not classified but security rules do make things difficult. 
GPS doesn't seem like an easy solution.

The computers log data from an experiment(s). If the time stamps in the 
log files for
one computer are off by 20-30ms from the time stamps in the log files of 
another computer
then the results of the experiment could be impacted.

However if all computers were off by the same offset from official time  
of a few seconds, it wouldn't matter.
Off by more than a few seconds wouldn't make the data unusable but might 
cause some confusion when we go to find the right log files.

The rubidium units I see on E-bay look like they were designed to go in 
a CD player. Would I need
additional hardware to connect it to a computer and software to read it 
as a clock source?

On 08/01/2012 01:24 AM, Chris Albertson wrote:
> On Tue, Jul 31, 2012 at 7:46 PM, Kennedy, Paul<P.Kennedy at fugro.com.au>wrote:
>> Exactly so.  you can purchase a GPS receiver for well under $100 connect
>> it to a serial port + pps on any of the pc's and have microsecond
>> accuracy in a few hours.  This 'master' can then serve time to all other
>> PC's.  The systems will then behave for years of unattended use.  It is
>> a far more cost effective solution.
> The OP said he can go into another room and connect to the Internet can
> sync a computer.   It seems to me that there might be some rule that
> prevents wires going into the room he works in, else why not simply run an
> Ethernet cable.   Many places do have such rules.  He might work in a place
> where they process classified information.  In that case they might not
> allow an antenna cable or any kind of wire to penetrate the room boundaries.
> If I have guessed correctly then what he needs  is an atomic clock.  Buy a
> few of those $40 Rubidium units that are on eBay
>> regards
>> pk
>> --
> Chris Albertson
> Redondo Beach, California
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