> From: Dave Hart <daveh...@gmail.com> > Date: Tue, 10 Mar 2009 08:56:14 -0700 (PDT) > Sender: questions-bounces+oberman=es....@lists.ntp.org > > On Mar 10, 3:44 pm, "Richard B. Gilbert" <rgilber...@comcast.net> > wrote: > > You might want to take a look at the work of Poul-Henning Kamp (PHK). > > He used Soekris 4501 single board computers together with a GPS receiver > > to make a highly accurate clock. This was long enough ago that most of > > the hardware he used is no longer available new but it might give you > > some ideas. > > Seconded. FreeBSD will give you better timekeeping than Windows. If > the difference between a few microseconds and a few hundred > microseconds is no problem, my recent Windows releases are fine. But > if you're dedicating a small PC to the task, care about those > fractions of a millisecond, and can manage FreeBSD, it's the gold > standard for NTP.
To get an idea of the fanaticism involved, several years ago, Kirk McKusick and my former boss here in Berkeley counted the machine cycles in the FreeBSD kernel for the PPS response(all done in the interrupt service routine) and used that to correct the time. Of course,in the days of 16 and 40 MHz systems, this was a bit more important. -- R. Kevin Oberman, Network Engineer Energy Sciences Network (ESnet) Ernest O. Lawrence Berkeley National Laboratory (Berkeley Lab) E-mail: ober...@es.net Phone: +1 510 486-8634 Key fingerprint:059B 2DDF 031C 9BA3 14A4 EADA 927D EBB3 987B 3751
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