[time-nuts] Thunderbolt GPS TimeKeeper

Chris Albertson albertson.chris at gmail.com
Mon Jan 23 13:29:24 EST 2012

On Sun, Jan 22, 2012 at 11:18 PM, David J Taylor
<david-taylor at blueyonder.co.uk> wrote:
>>> As of 01 January 2012 all three of my systems began to Sync.the year
>>> incorrectly. I am using Trimble TimeKeeper ver. 1.02. The year 2020 now
>>> appears on my PC's, the time however is correct. I use Windows NT, XP, and
>>> Vista. The Date is correct when displayed in TBoltMon. I reinstalled the
>>> software on a spare PC that is not connected to  my network, same results.
>>> Is there a fix somewhere or am I overlooking something obvious?
>>> Regards, Dennis WD8DCJ
>> If you are keeping a network of PCs in sync to time the software to
>> use is "NTP".
>> http://www.ntp.org/
> .. with setup instructions and hints on using with Windows here:
>  http://www.satsignal.eu/ntp/setup.html

This is not an NTP list.   Best to ask about NTP at
questions at lists.ntp.org
Opinion on that list is that for best result, build the latest NTP
from source.  Executable files (.exe) that you find may not be recent
builds.)     Go the the above email for details

So back to time.   If the goal is keeping good time then it is best
not to use Microsoft Windows.  There are good technical reasons having
to do with the way MS Win. keeps and adjusts time.  The bottom line is
that you will never be able to do better then about the millisecond
level even with a directly attached GPS.   Using another OS, BSD or
Linux you can do almost three orders of magnitude better.  (Three
orders is huge.)  The OS and software is free and all you need is any
computer that has a physical serial port, not USB but a real DB9
connector.  This is a good use for a 10 year old notebook PC.  (The
computational load is trivial so even a 486 class computer is OK)

If you run BSD or a newer Linux then Pin-1 on the DB9 can be used for
time interval measurement at almost 1 uSec precision.   You can use
this for many things, NTP being just one of them.   If you have
multiple DB9 type serial ports then you can time tag multiple channels
to about a uSec or two. (certainly 3E-6 level)

Then if the Windows PCs need correct time they could use the server
running on the old BSD based notebook PC.  Zero added cost assuming
you can find and old computer.  Then you also have a tool that can
time tag any pulse at the uSec level.

Chris Albertson
Redondo Beach, California

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