[ntp:questions] Local Time

Steve Kostecke kostecke at ntp.isc.org
Wed Mar 14 20:36:19 UTC 2007

On 2007-03-14, wiechman.spam at gmail.com <wiechman.spam at gmail.com> wrote:
> On Mar 14, 2:05 pm, ober... at es.net (Kevin Oberman) wrote:
> [---=| Quote block shrinked by t-prot: 34 lines snipped |=---]

<snip: 10 lines of signatures>

Please think of the readers and trim the quoted material in your reply.

> We need ntp to serve out the local time. We have around 1500 wireless
> radios that don't provide the ability to set an offset. Not the end of
> the world, but then everything in the logs and elsewhere is dated in
> UTC which is a real pita - confuses the hell out of some of our
> installers.

NTP synchronizes computer clocks to a timebase.

The most commonly used NTP timebase is UTC ("traceable to NIST") which
is obtained from reference clocks (e.g. GPS, or WWVB) or from remote
time servers (which are ultimately syncronized, possibly through other
remote time servers, to a reference clock).

But UTC is not the only timebase that you can use. Some applications use
the Undisciplined Local Clock, or LocalCLK, as the timebase.

One solution to your problem is to set up a dedicated (i.e. performs no
other function) time server (on UNIX or a Unix-like OS) and set your
hardware clock to the local time and then "synchronize" your ntpd to
the LocalCLK.

Prior to putting this system in to production I would calibrate the
clock by allowing that ntpd to synchronize to some remote time servers
(form several days) and calculate the correct PLL offset frequency
(for the drift.file). During the calibration procedure it is important
that the system is exposed to the ambient conditions of its operating

Steve Kostecke <kostecke at ntp.isc.org>
NTP Public Services Project - http://ntp.isc.org/

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