[time-nuts] Set time on Solaris computer from HP 58503A
gigneil at gmail.com
Wed Dec 17 00:08:40 EST 2014
Of *course* you can sync to better than a millisecond on the LAN. There's
not a machine worldwide at my employer more than 600 micros off from each
other, and the machines at my house are within 50.
You wanna start talking the sync-e+1588 test I'm doing? We're speaking in
My LTE Lite is the only USB pps I have presently - and it pulls my time
well over 200 milliseconds off reference. That's a massive change from the
1 or less I am from the internet and the 50 micros from the other boxes.
On Sun, Dec 14, 2014 at 10:30 AM, Chris Albertson <albertson.chris at gmail.com
> I would still like to experiment with it. As I wrote earlier I bought this
> > for a frequency reference, not a clock, but I would not object to a bit
> > fun messing around with it.
> If the goal is just getting good enough time onto the Solaris machine then
> use NTP and some pool servers on the Internet. You get about 10
> millisecond level accuracy and the cost is zero. If you have solaris
> running you might even have this all setup and running. If not do this as
> the first step and verify it works.
> If 10ms is unacceptable, next step is to connect the PPS signal. Doing
> this will move you from milli to micro second level accuracy. It is easy
> if the Solaris machine has a real serial port. If you have to go through
> a USB dongle you loose about an order of magnitude accuracy but this is
> still very good.
> There is zero point in buying a special computer to run NTP. Just use any
> computer you own that is already running 24x7. Of course if you don't have
> a computer that runs 24x7 then you would look for one that uses very little
> Don't worry to much if the USB connection skews the time on the NTP server
> by some tens of microseconds, your server can't transfer time to your other
> computers on the LAN any better than millisecond level so a few tenths of
> an millisecond hardly mater.
> My opinion of computer time is that for normal use being a few milliseconds
> off is OK because the typical monitor is refreshed no faster than 100Hz so
> you have lag cause by screen refresh times even if the internal clock is
> dead-on perfect. Same for disk time stamps, these is lag in the IO system
> Chris Albertson
> Redondo Beach, California
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