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Re: Time references (UT vs. GPS)



Scott NX7U wrote about GPS, UTC and all that fun stuff...

I work with systems that are synchronized with GPS, and
that 13 second difference to UTC is very much part of my
soul nowadays.

There are three time scales that show up in AMSAT circles.

UTC is defined by vibrating atoms, but
is tweaked to stay
roughly synchronized with Earth's rotation. GPS is not tweaked,
but runs at the same rate. UT1 is derived from Earth's rotation,
which wobbles around a bit. It is primarily of interest to
navigation, though it matters if you want to compute the
exact instant of local noon so you can align an antenna
by sighting along its shadow. Last time I did this I
just used my longitude, and didn't even bother with
the Equation of Time. I know, a slacker. :-)

I actually possess a *paper* copy of NIST Special Publication
432. Got it (along with a nice QSL card) in response to
signal report to WWVH.

You may have noticed that there haven't been any leap
seconds recently, and none are planned - a sharp contrast
to events up a to a couple of years ago. I was told why,
but still don't quite believe it...

Laura Halliday VE7LDH     "Que les nuages soient notre
Grid: CN89mg                       pied a terre..."
ICBM: 49 16.05 N 122 56.92 W     - Hospital/Shafte

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