[aprssig] Dumb tracker question

Wes Johnston, AI4PX wes at kd4rdb.com
Sat Sep 30 22:39:27 EDT 2006


You are correct.... I'd forgotten that some GPS units contain an internal
magnetic compass.  Usually there is a setting that is adjustable that allows
the compass to work when the speed is below XX mph.

Wes


On 9/30/06, Richard Amirault <ramirault at verizon.net> wrote:
>
> ----- Original Message -----
> From: "Wes Johnston, AI4PX"
> Subject: Re: [aprssig] Dumb tracker question
>
>
> > If the heading is 180 degrees wrong, maybe turning the GPS antenna on
> the
> > car so that the cords comes out near the rear of car will help and
> correct
> > the heading?  lol.... couldn't resist!!!
> (snip)
>
> Not as far fetched as you might think.  Many handheld GPS units will give
> BEARINGS to waypoints that are 180 deg off if they are not held properly
> ..
> that is face up with the "top" of the unit towards the direction of
> travel.
> For instance if you set the GPS screen to show you an ARROW that points
> toward the waypoint (that tell you the direction you need to travel to
> reach
> that waypoint)  if you reverse the orientations of the GPS in your hand
> (put
> the "top" of the unit facing you instead of facing the direction of
> travel)
> the arrow will point 180 degrees in exactly the opposit direction you need
> to go.  Similarily, if you leave the orientation of the GPS alone and just
> walk backwards .. or, if in a vehicle, drive backwards, the same thing
> will
> happen.
>
> I discovered this when I was an active Geocacher some time ago.
>
> Richard
> Amirault                                N1JDU                Boston,
> MA, USA
> n1jdu.org                                   "Go Fly A Kite"
>
>
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