7 JAN - 2325 CST
Gentlemen...
I have been reading all the various ways to find true north, most of
them quite easy to use. The plotting of the shadow cast by a vertical
stick is the most time consuming, but the easiest because it does not
require knowing accurate local sunrise and sunset times - just a
periodic plot of the shadow every 15 or 20 minutes for about two hours
before and after estimated "local noon".
If you have a good magnetic compass, liquid damped with a built-in
compass circle of 360 degree marks (360 divisions), and you are not
near any large metallic body such as your tower, you can easily
calculate any true heading or bearing using the following menomic
formula -- "Can Dead Men Vote Twice At Elections" = CDMVTAE
*C*ompass heading plus east *D*eviation = *M*agnetic heading plus east
*V*ariation = *T*rue heading -- *A*dd *E*ast. (Subtract West values)
Deviation in this formula is a known correction factor to be used when
the compass is installed in an aircraft or ship. For our purposes, it
can be ignored -- unless your antenna is being mounted on an aircraft
or ship. :>
There is also a menomic formula for for converting a True heading all
the way to a Compass heading. Does anyone else remember it? :>
73 - Dick Isely, WD9GIG
--
FAQ on WWW: http://www.contesting.com/towertalkfaq.html
Submissions: towertalk@contesting.com
Administrative requests: towertalk-REQUEST@contesting.com
Problems: K7LXC@contesting.com
Sponsored by Akorn Access, Inc & KM9P
|