[time-nuts] Accurate Thunderbolt position

Tom Van Baak tvb at LeapSecond.com
Wed Jul 15 05:15:13 UTC 2009


Mark,

Nice work on the Z12. Now one idea for you on the TBolt.

Before you spend too much time trying to nail it down to the
foot or inch you might want to see what effect being off by
a couple feet or meters actually has on your TBolt timing.
For this you want to compare the 1pps output against a
good local standard (I hope you have a cesium by now).

I don't know for sure, but I wonder if there could be enough
other error sources in the entire timing chain that your
super precise position is moot for typical cheap GPSDO.

I would say the same thing to someone spending a great
deal of time regulating temperature to 0.01 C -- at some
point minor variation in temperature is no longer the low
hanging fruit for a GPSDO; further effort does not pay off,
or is not even measurable.

So I wonder at what point in the real life operation of a
Z3801A or TBolt that further steps in accurate position
are no longer fruitful?

Has anyone on the list deliberately offset their XYZ position
by a meter or two or three to see what effect it has on the
10 MHz stability or the 1pps accuracy (again, measured
against a suitable local atomic clock).

/tvb




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