[aprssig] garmin gps and compass heading

[Wes Johnston]

My application was of a Search and Recreation (SAR) system... for tracing 
(retracing) the contours of a lake shore while fishing.  A GPS with a 
compass built in would be mounted on the head of a trolling motor and a pic 
processor would swivel the motor to face the way GPRMB told it to face. 
Seems now that all I have to do is set the switchover point the gps uses to 
switch from a compass measured heading to a calculated heading at some 
really fast speed like 20mph so it always uses the internal compass.

Wes
----- Original Message ----- 
From: "Jan T. Pharo" <la2bba at jpharo.net>
To: "TAPR APRS Mailing List" <aprssig at lists.tapr.org>
Sent: Monday, May 01, 2006 11:13 AM
Subject: Re: [aprssig] garmin gps and compass heading


"Richard Amirault" <ramirault at verizon.net>, Mon, 1 May 2006 08:30:08
-0400:

>
>Maybe .. but that was not what I was saying .. if you are using your GPS to
>either:
>1. follow a "route" (a bunch of waypoints) or
>2. arrive at a single waypoint
>
>you will NOT get proper directions UNLESS the GPS is facing the proper
>direction ("forward")

It will, in my experience (GPSMAP76 at sea). I can swivel it 90º or
more - at sea, I am often in front of the navigator which is following
a route and an autopilot managing the tiller, and like to turn it with
the display facing forward. When I approach a waypoint where I have
planned to turn starboard, a message "turn right" will be displayed,
as expected, even if that's to the left side of the GPS at the moment.
>
>Of course a GPS knows it's own position independant of orientation, but
>that's not the problem, the problem is telling you where (left, right, 
>back,
>forward) the place is that you want to go.

(It also knows in which direction it is moving.)
>
>Again these are with handheld GPS units, not hocky puck types .. I haven't
>tested those.

My experience is with handheld models, even if mounted. Dunno with
"mice"/pucks.

-- 
73 de Jan, LA2BBA
Hvaler, Norway

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