[aprssig] garmin gps and compass heading
bruninga at usna.edu
Sat Apr 29 11:22:29 CDT 2006
I need 3 of these magnetic heading chips for our
next satelltie to build the magnetometer. ANyone
have any experience with them? Bob
>>> ramirault at verizon.net 04/28/06 8:54 PM >>>
----- Original Message -----
From: "Wes Johnston"
Subject: [aprssig] garmin gps and compass heading
Does anyone know if the garmin units with compasses output a seperate
compass heading? Note that the compass heading may be different than the
direction of travel (for example if the unit is held horizontal and moved
backwards or left/right.) My intent is to have a serial compass that shows
which way the gps unit is oriented.
No idea with those garmins. You do realize that a 'heading' (towards the
next waypoint for instance) on the display IS dependant on the orientation
of the GPS .. at least hand held units (I haven't experimented with any
hocky puck units).
A GPS expects to be held, face up, with the "top" of the unit towards the
direction of travel. For instance if you are in a car, moving forward, and
the GPS says that the next waypoint is 90 deg to the right. THEN, if you
stop and backup the car WITHOUT moving the GPS in any way .. the GPS will
tell you that the waypoint is now 90 deg to the LEFT!! so long as the car is
still moving backwards.
What all this has to do with compass output (with those GPS units with an
electronic compass.. the only ones in consideration here I hope) ?? I have
Richard Amirault N1JDU Boston,
n1jdu.org "Go Fly A Kite"
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