Re: Date/Time accuracy (was Re: First TOM1 image under Rob's Software)

[Chris Albertson <chrisalbertson90278@yahoo.com>]

--- Robert Creager <Robert_Creager@LogicalChaos.org> wrote:

> 
> Hey Robert,
> 
> The reason his machines (Linux) agree with his watch as I setup a NTP
> server


> > Tom,
> > 
> > PC clocks are not known for their accuracy.
> > 
> > I would suggest that you syncronize your machines with NIST using
> > their internet service.  See:
> >   http://www.boulder.nist.gov/timefreq/service/its.htm

NTP is about three orders of magnitude better solution then the
above.  The problem with "syncing" cocks is that periodically
time "jumps". (It might even "jump" backwards.) This is seriously
not good if you happen to be running an interval timmer off the
system time.

While the above adjusts the absolute time, NTP adjusts the clocks
_rate_ of advance.  Much better to control the rate.  

The impressive thing about NPT is is ability to keep time sync'd
to the milli micro second level when the comunication delays are
much longer.  Ok not some amazing if you think about phase locked
loops, servos, satistics of large numbers and the like.


=====
Chris Albertson
  Home:   310-376-1029  chrisalbertson90278@yahoo.com
  Cell:   310-990-7550
  Office: 310-336-5189  Christopher.J.Albertson@aero.org
  KG6OMK


		
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