A gyro compass is only as accurate as its initialization. So what
standard do you propose we use to initialize the gyrocompass?
Except for the really dumb mistake of saying longest when shortest was
correct word (????) the method I mentioned works very well. No accurate
time keeping required. You just mark the location of the end of the
tower's (or fence post or stick in the ground or whatever's) shadow
several times during the day and connect the dots in a smooth curve.
The apex of the curve is when the shadow points true north. Short
shadow in summer, hard to tell where it points? No problem, the curve
is symmetrical so you can just bisect the curve and there you have true
north through the tower's center (or your stick or...) You don't need to
record any data or note the time when you mark the location of the end
of the shadow.
Works in any season. No arithmetic involved. Free. Takes several
hours to get the result but you are only actively involved for a couple
minutes every once in a while, say 1 hour intervals. Continental drift
may introduce error within several centuries.
Patrick NJ5G
On 1/27/2017 10:33 AM, Herbert Schoenbohm wrote:
This large sundial (Point Udall) is just down the road from my house
and is the Easternmost point of the U.S. in North America.
http://www.atlasobscura.com/places/point-udall
On 1/27/2017 11:14 AM, Hans Hammarquist via TowerTalk wrote:
I like that method. Will try it.
I have one problem though, you will have the time for the solar noon
at that day but you will only know it after the day is over. As the
solar noon changes a little every day you don't know what it is the
next day. You might be off by several part of one degree. :-) Just
kidding!
I think your method is way good enough for most if not all our
purposes. If you need it better you have to get a gyro compass. That
will show the true north, but how picky do you want to be?
73 de,
Hans - N2JFS
-----Original Message-----
From: Ed Karl <edk0kl@centurytel.net>
To: towertalk <towertalk@contesting.com>
Sent: Thu, Jan 26, 2017 9:40 pm
Subject: [TowerTalk] Strange etc
A. The time between local sunrise and sunset is solar noon, in North
America is in the middle.
Therefore any shadow point to True North.
B. With most HF antenna having 3db points for the forward lobe having
the smallest angle of 30 degrees
why are we picking nits over finding magnetic north away from buildings
and the deviation that day to
compute True North to get 1 degree accuracy?
To me on a circuit to ZS or G, it's "good enough" with the old sundial
method from here in Missouri.
Or what am I missing?.
73!
ed K0KL
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