[time-nuts] Loran, GPS, Lightning, Timing

Poul-Henning Kamp phk at phk.freebsd.dk
Tue Jun 24 14:17:28 EDT 2014

In message <06013AA10880459380352E3FB29C4B5C at pc52>, "Tom Van Baak" writes:

>2) Can you imagine applying this entire process in reverse. That
>is, instead of using GPS to timetag lightning strikes, use lightning
>strikes to synchronize a global network of local clocks.

The first input you need is the exact longitude/latitude of the
lightning bolt.

The easiest way to do that is with a set of GPS synchronized receivers,
aaaand we're back to sqare one!

The next issue is that lightnings are seldom vertical, they can
trivially wiggle many hundred meters sideways, so at absolute
best your jitter is going to be no better than the microsecond
domain, and probably much worse, increasing with distance.

But there's a workaround:  if you have the right kind of "pregnant"
thundercloud overhead, a plain firework rocket trailing a thin
grounded wire will, on your command, get you a lightning strike.

Not only are these lightnings almost always entirely vertical, they
are also particular sharp and potent (for that very reason).

So if you live in the right kind of place, you *could* implement
a daily clock synchronization service much more spectacular
than a mere "ball-drop".

I belive the US electrical grid industry runs a joint research
center somewhere in northern Florida, using this method to test
lightning protection of the power grid components.

I suspect they ignite their rockets using remote control.

Poul-Henning Kamp       | UNIX since Zilog Zeus 3.20
phk at FreeBSD.ORG         | TCP/IP since RFC 956
FreeBSD committer       | BSD since 4.3-tahoe    
Never attribute to malice what can adequately be explained by incompetence.

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