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Re: North



Hi Bill,
    All calculations are based on true north. There could be some "add ons"
to calculate magnetic north but to do this well for any point on the globe
is quite complex. I know the south magnetic pole moves about 20 km each day
and I would assume the north magnetic pole does the same thing. To work out
where true north is you can use a compass then add or subtract the angle to
find true north based on current data of what the angle between true north
and magnetic north is for your location (in Sydney it is about 13 degrees
and genrally increasing each year).

    If you know you longitude, then you can calculate when solar noon is and
if you are in Canada (I assume) then at solar noon, the shadow of your mast
or what ever you mount your antenna on will point to true north. If you mark
the point where the shadow goes to then you will have a reference position
to aim your antennas at when you want to recalibrate them.

    To calculate solar noon; you need to know you longitude from a map, gps
etc. For my QTH my longitude is 151 3' 46".(see
http://www.qrz.com/detail/VK2KGM).
Expressed as a decimal that is 151.06278 Degrees. The Earth rotates once
(360 Degrees) in 24 hours and so that is 15 degrees per hour. So my QTH is
151.06278/15 Hours ahead of UTC or GMT. Solar noon for me is at  0255 and 45
seconds UTC. In Canada you are not in the tropics and so the shadow will
always be to the north at solar noon. In Sydney, I am south of the tropics
and so the shadow will always be to the south (if ever so slight on the 22
December). In the tropics the shadow could be to either the north or the
south depending on the time of year and your latitude.

Hope this might be useful.

Regards,
Murray Peterson
VK2KGM

----- Original Message -----
From: "bgreene" <bgreene@junction.net>
To: "amsat-bb" <amsat-bb@AMSAT.Org>
Sent: Wednesday, January 31, 2001 3:50 AM
Subject: [amsat-bb] North


> Hello All,
>
> I have a question and have not been able to find an answer anywhere. I
hope
> someone can clear this up for me .
> When setting up antennas for sat work are they set up to magnetic north or
> true north. I would guess true but would like to confirm that .
>
> Thanks,
>
> 73 de VE7WFG DO00jk
> Bill
>
> ----
> Via the amsat-bb mailing list at AMSAT.ORG courtesy of AMSAT-NA.
> To unsubscribe, send "unsubscribe amsat-bb" to Majordomo@amsat.org
>



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