> > As I have said many times, in theory POSIX time is a form of TAI, being a > constant offset from TAI, but in practice (for those who care enough to buy > the hardware), POSIX Time is whatever GPS distributed NTP say it is.
Is that right? Looking at a nearby Stratum-2 reference (on a large university campus), I see a wide range of sources. PPS could be anything there's a driver for, of course, but the UK Janet and LINX Stratum 1s include MSF for UTC(MSF), USNO I presume means a radio source of UTC(USNO), CTD I think is an Italian radio source for UTC(IEN). This looks like a Stratum 2 that's aligned to a variety of independent sources of UTC, which are then synchronised by whatever mysterious means are used keeping UTC coherent. ian > xtick.uh.edu .GPS. 1 u 453 1024 377 174.04 -12.605 0.27 > .usno.pa-x.dec.c .USNO. 1 u 33 1024 377 151.95 -0.971 0.43 > -ntp-sop.inria.f .GPS. 1 u 564 1024 377 28.03 -1.394 0.06 > -ntp1.linx.net .PPS. 1 u 41 64 377 9.26 0.103 0.09 > -ntp0-p.ja.net .MSF. 1 u 875 1024 377 9.99 -1.533 0.35 > -ntp0.linx.net .PPS. 1 u 8 64 377 9.32 0.077 0.55 > *ntp0.inrim.it .CTD. 1 u 48 64 377 35.71 -0.035 0.09 > -ntp2.linx.net .GPS. 1 u 1 128 377 8.91 -0.326 0.26 > .tick.ucla.edu .GPS. 1 u 754 1024 377 184.19 2.133 2.67 > webmail-dz19.si 0.0.0.0 16 u - 1024 0 0.00 0.000 16000.0 > .tock.usno.navy. .USNO. 1 u 199 1024 377 137.50 4.232 1.56 > .ntp2.usno.navy. .USNO. 1 u 467 1024 377 142.82 4.710 1.59 > -ntps1-0.cs.tu-b .PPS. 1 u 18 1024 377 39.47 0.242 0.21 > +ntps1-1.cs.tu-b .PPS. 1 u 54 64 377 37.86 -0.063 0.70 > -ntp1.inrim.it .CTD. 1 u 25 64 377 34.93 -0.096 0.05 > +ntp2.inrim.it .CTD. 1 u 29 64 377 35.48 -0.037 0.12 >
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