[ntp:questions] Isolated Network Drift Problem

Unruh unruh-spam at physics.ubc.ca
Wed Nov 26 00:55:57 UTC 2008

Steve Kostecke <kostecke at ntp.org> writes:

>On 2008-11-25, Cal Webster <cwebster at ec.rr.com> wrote:

>> On Tue, 2008-11-25 at 17:12 +0000, Unruh wrote:
>>> "Richard B. Gilbert" <rgilbert88 at comcast.net> writes:
>>>> Cal Webster wrote:
>>> Or connect your system to the net for a while allowing only ntp
>>> packets in or out and use one of the time servers on the net.
>> Unfortunately, connection to the Internet is not an option I'm allowed
>> to consider.

>Another option you could consider is the dumbclock driver. This uses a
>serial link to transfer time stamps from one system to another.

>>> The Garmin 18LVC only claims an accuracy of the PPS of about 1micro
>>> second. However getting the time in can be done to the usec level.

>usec == micro second

Yes. I am saying that the GPS time signal is accurate to 1usec and that the
getting the timestamp from that PPS into the computer itself can also be
done to roughly that level. The comment I was replying to stated that GPS
was good to 40nsec but that it took almost a millisecond to get the data
into the comptuer. 

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