[Beowulf] precise synchronization of system clocks

Lombard, David N dnlombar at ichips.intel.com
Tue Sep 30 14:24:59 PDT 2008

On Tue, Sep 30, 2008 at 10:47:05AM -0700, Lawrence Stewart wrote:
> On Sep 30, 2008, at 12:07 PM, Lux, James P wrote:
> >
> > The grottiest grungy GPS receiver can probably do 100ns on its 1pps
> > tick,
> > and most are in the 20ns range.  There ARE receivers that have
> > systematic
> > errors (i.e. Some sort of sawtooth in the error) and, of course,
> > there are
> > countless schemes to compensate in one way or another.
> So someone with some grad students and soldering irons should hook up
> the 1 pps
> output of a GPS to, say, the carrier detect pin on the unused RS232
> ports of all their
> nodes, and write some software...

Using GPS receivers to drive the system clock, e.g., for your own private
low-stratum NTP master, is well described and easily accomplished.

Doing the same with a WWVB, MSF, DCF RX is also well described. For WWVB,
at least, it's sadly tougher to get the parts in single quantity :(

GIYF in any event...

David N. Lombard, Intel, Irvine, CA
I do not speak for Intel Corporation; all comments are strictly my own.

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