I think the idea is that you calibrate the true north against the READING on
the controller. I believe that declination is rather constant at least in a
short time frame, all you have to do is to direct the antenna in a know
direction, rotate the sensor until you read that direction on the controller.
Unless you have variations in the declination the reading should keep up.
(I recommend a north-seeking plastic owl if you have problems finding true
north:-)
73 de Hans - N2JFS
-----Original Message-----
From: Rroger (K8RI on TowerTalk) <k8ri-on-towertalk@tm.net>
To: towertalk <towertalk@contesting.com>
Sent: Tue, Feb 1, 2011 1:20 am
Subject: [TowerTalk] A word of caution Was Wireless tower direction indicator?
Although the idea is sound, easy to implement in one form or another
there are many places in the US (and the rest of the world) where
magnetic and true North differ substantially. The extremes in
continental US are in the NE and NW. IOW New England states (-20 deg)
and parts of Washington state(+ 20 degrees) with the East coast running
-10 and the N Central US down to Mexico and the tip of the Baja
peninsula running +10. Zero degrees runs from the Sestern edge of
Hudson Bay to near New Orleans.
http://en.wikipedia.org/wiki/File:IGRF_2000_magnetic_declination.gif
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