[time-nuts] Practical Survey-In Accuracy?

Attila Kinali attila at kinali.ch
Thu Aug 28 09:41:55 EDT 2014


On Thu, 28 Aug 2014 06:30:14 -0700
Bob Stewart <bob at evoria.net> wrote:

> Is wood, nails, and asphalt shingle really that big of a problem at these 
> frequencies?  The antenna is within 2 ft of the highest point of the roof.

Consider this: A lot of people complain about the reflections caused
by trees. But what is a tree? It's mostly air and a few leaves, with
a branch here and there.

Also: 60cm is less than 2λ. ie the roof is in the near field of the
antenna, where everything causes a change of the antenna behaviour
(resonance frequency, radiation pattern, phase centre etc)

Depending on what you do with the GPS signal, you might or might
not care about that. If you are a nutty time-nut and want to
wring out ever last bit of jitter out of your PPS, then you
will care about the effect of the roof.


			Attila Kinali

-- 
I pity people who can't find laughter or at least some bit of amusement in
the little doings of the day. I believe I could find something ridiculous
even in the saddest moment, if necessary. It has nothing to do with being
superficial. It's a matter of joy in life.
			-- Sophie Scholl



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