Magnetic declination is different for different places on the earth, and it
is changing at an increasing rate. Some geophysicists believe that we are
approaching a "pole swap" event, like the earth's magnetic field has done
every 40,000 years or so...
But, back on topic, there is a quick and easy way to determine the magnetic
declination at your qth, how it has changed, and the prediction as to how it
will change in the future. Visit NOAA's Geophysical Data Center's Magnetic
Declination calculator:
http://www.ngdc.noaa.gov/geomagmodels/struts/calcDeclination
Your tax money at work!
73,
Mickey N4MB
On Wed, Feb 2, 2011 at 10:30 PM, Hans Hammarquist <hanslg@aol.com> wrote:
>
> 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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> TowerTalk@contesting.com
> http://lists.contesting.com/mailman/listinfo/towertalk
>
--
Mickey Baker
Fort Lauderdale, FL
“Tell me, and I will listen. Show me, and I will understand. Involve me, and
I will learn.” Teton Lakota, American Indian Saying.
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