[LEAPSECS] real-time UT1 realisation

Tom Van Baak tvb at LeapSecond.com
Thu Sep 22 13:15:26 EDT 2011



> Eyeballing it says around a couple of milliseconds, which, unless

> you have done things to your hardware, is lost in the NTP noise.


That was my conclusion too. It's one thing to work with hardware
at the micro- nano- or picosecond level. But the threshold with
PC's, even PC's running NTP, is so relaxed that I figured almost
any hack that uses a dut1 database would do the trick. The one
I usually fetch is http://maia.usno.navy.mil/ser7/ser7.dat.

Yesterday DUT1 was -0.30806, today is -0.30862, and tomorrow
will be -0.30937. So it seems to me you could implement the
google ntp server lie() function with essentially one line of code
and it would be accurate to better than 1 ms. No interpolation,
no filtering, no prediction; just a table lookup. Hard to beat that
performance/simplicity ratio.

/tvb



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