[ntp:questions] serialPPS+gpsd+ntpd large offset & jitter

Thomas Laus lausts at acm.org
Fri Jan 14 16:48:23 UTC 2011


On 2011-01-12, Chris Albertson <albertson.chris at gmail.com> wrote:
> I had a motherborad fail a few weeks ago, (big black burned hole where
> a voltage regulator caught fire) so before dumping the thing in the
> trash I looked it over for good salvage.    I found two TCXOs that
> were used for the CU clock and for the graphic system but the real
> time clock chip had a cheep 32Khz watch crystal on it.  These sell for
> maybe 10 cents each.
>
> Seems to me that if you want to build a first class NTP server it
> would not be hard to unsolder the watch crystal and replace it with a
> length of coax cable that heads off to a precision oscillator.    I
> had little to loose as the board was already dead and found the watch
> crystal comes off very easy.  Some day I'll build a 32K oscillator
> that is locked to the 10Mhz laboratory frequency reference
>
Since you are going to perform some circuit board repairs, there is a
TAPR kit you might have interest:

http://www.tapr.org/~n8ur/Clock-Block_Manual.pdf

The clock crystal is removed and replaced with this board and the PC
will be phase locked with the GPS broadcasts.  The designer, N8UR, has
a lot of time related information on his website as well.  He has
replaced the motherboard clock on a low powered Intel Atom with this
kit.  SMT board soldering is not for everyone, but since you are
already planning on replacing your motherboard clock chip, you might
want to review this site for various ideas:

http://www.febo.com

Tom

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