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brucedownunder2
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Joined: 14/09/2005
Location: Australia
Posts: 1548

Posted: 02:57am 18 Aug 2011

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I have a amateur radio beam antenna with a rotator ..

My question is ,, how do I figure out what compass bearing I would have to rotate to for my "other" end . Is there a map or Google earth that I can get this info from .. Say , bring up my end on Google earth ,write it down then do the other end , write it down , and subtract between the two ??. My location is Clagiraba australia and my brother is Bribie Island Australia ( for example). I think for amateur radio the suburban location s will be accurate enough.

Someone may be able to direct me ,thanks

Bruce

Bushboy

Tinker

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Joined: 07/11/2007
Location: Australia
Posts: 1904

Posted: 01:55pm 18 Aug 2011

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Bruce, in time past I too had a large amateur beam antenna with a rotor. I also have done a comprehensive navigation course back then but the maths for it might have escaped the brain box by now

.
Anyway your easiest way would be to find a map that has both locations on it. Draw a line between these and measure the angle compared to top of map (North) being zero degrees. This gives you the true bearing.
For a compass bearing you have to add or subtract the local magnetic variation that applies to your area.
For longer distances you have to use the great circle direction. This is basically the angle of a string on a globe of the world that is stretched from your location to the destination. I actually have a world map (with Perth at the center) that shows the great circle bearings to everywhere else - it looks real weird. But its only good for my location.

I would not bother with Google earth lat/ long figures, the above mentioned maths come into play with these. But, I'm sure there is a program (google it) that does it for you and tells you the bearing on the net somewhere.

A quick googling found this site:compass direction

Have fun Edited by Tinker 2011-08-20

Klaus

KiwiJohn
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Joined: 01/12/2005
Location: New Zealand
Posts: 691

Posted: 01:09am 19 Aug 2011

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What you need is 'Great Circle Bearing', there are many site on-line that will calculate this for you.

However, the easiest may be to print a Great Circle map centred on your location, have at look at this site which may lead you to what you want..

http://www.hard-core-dx.com/nordicdx/dxlab/circlemaps.html

KiwiJohn
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Joined: 01/12/2005
Location: New Zealand
Posts: 691

Posted: 01:10am 19 Aug 2011

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But for your application, two locations within Australia, Tinker's method of just looking at a common Mercator's projection map is probably quite close enough.

Edited by KiwiJohn 2011-08-20

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