Re: Clock Discrepancy

[email protected] wrote:
> Atomic clock supposedly synced ( sp ? ) by radio to some standard from out west ( Denver ? ) is always at least 2 seconds behind the computer. I'd think they'd be spot on. Comments ?
> 
> 

OS not stated.

Control Panels : Date and Time
    Internet Time
       Update Now    (time.nist.gov)

That's an NTPD update being done on the spot.

Now, compare standards again. Are they synced now ?

Even "national standard" time sources, have been off by 20 minutes,
under failure conditions. Keep your weather eye peeled for shenanigans.

*******

PC clock drifts after a sync event. All PCs do this,
because the clock on the motherboard is +/-100ppm.
That's a pretty big error, and a pretty grotesque
time reference source.

Windows Time syncs once a week (assuming time.nist.gov
is accessible and so on), allowing *plenty* of time for
accumulated drift after the sync is done.

The Windows clock subsystem does not "dribble out"
the drift rate. Some third party ntpd implementations,
adjust the local clock according to measured drift rate,
and this helps keep the deterministic drift to a minimum,
until a week has passed. Maybe every 15 minutes, such a
software might make a 0.01 second correction, or whatever
the first order drift rate happens to be.

Some of the drift is a "wander" of unknown direction and
magnitude. Even recording and analyzing such error, leads
to no better ability to predict it in the future. This
is the limit of what "blind correction" can do for you.

Summary: Do an immediate "sync" by clicking the button,
          *then* check the time.

    Paul