Garmin 196 acting up

I have a Garmin 196 and just in the past week or so it is acting
strange. I get a signal just fine, but when I am standing still it
constanly changes headings. It never moves in a direction, just turns
in circles sporatically. Once I begin to move, it tracks just fine.
But as soon as I stop, it constantly changes headings again. Anyone
else experience this? I upgraded to the latest software, but that
didn't fix the problem.

Glenn

"Glenn Westfall" wrote in message
...
I have a Garmin 196 and just in the past week or so it is acting
strange. I get a signal just fine, but when I am standing still it
constanly changes headings.

I don't have that GPS, but that sounds normal to me. Probably if you zoom
in far enough, you'll see that it IS showing a change in your position.
Even a tiny position change can be converted to a heading change. The
position change is simply a result of variations in the error, when you are
stationary.

I suppose the software ought to dampen this effect by updating heading only
when a large enough position change occurs, but my low-end handheld Garmin
doesn't do any such dampening.

Why you've only noticed this in the past week, I can't say. Maybe it isn't
supposed to do it, and this is some sort of glitch. I wouldn't guess that's
the case, but obviously I can't say for sure.

Pete

GPS only computes heading from "last known position" to "current position",
if you are not walking.. the "last known and current" are the same.. there
is no heading to compute.. granted with minor errors of cheap handheld GPS
units.. the "movement" could be minor inches or parts of an inch as the GPS
computes it's position.. and that will cause a heading change..

BT

"Glenn Westfall" wrote in message
...
I have a Garmin 196 and just in the past week or so it is acting
strange. I get a signal just fine, but when I am standing still it
constanly changes headings. It never moves in a direction, just turns
in circles sporatically. Once I begin to move, it tracks just fine.
But as soon as I stop, it constantly changes headings again. Anyone
else experience this? I upgraded to the latest software, but that
didn't fix the problem.

Glenn

BTIZ wrote:

GPS only computes heading from "last known position" to "current position",
if you are not walking.. the "last known and current" are the same.. there
is no heading to compute.. granted with minor errors of cheap handheld GPS
units.. the "movement" could be minor inches or parts of an inch as the GPS
computes it's position.. and that will cause a heading change..

My Garmin 295 does a good job of filtering this behavior.
I have it in the "Heading Up" mode; the map presentation does
not rotate when the airplane is sitting still.

Wonder what the OP's SNRs look like? My 295 typically shows
resolution (DOP?) of just a few feet. I have to move
the aircraft a mininum of about 10ft to get it to register
a heading change.

For example, as I taxi up to the hangar, I make a 90 deg turn in
front of the hangar door. I travel less than 20ft on the new
heading, and that is just barely enough for the 295 to register
the new heading by rotating the map...

MikeM

on the other hand.. did you check the NOTAMs to see if there is any GPS
error reports or possible jamming going on in your area?

BT

"Glenn Westfall" wrote in message
...
I have a Garmin 196 and just in the past week or so it is acting
strange. I get a signal just fine, but when I am standing still it
constanly changes headings. It never moves in a direction, just turns
in circles sporatically. Once I begin to move, it tracks just fine.
But as soon as I stop, it constantly changes headings again. Anyone
else experience this? I upgraded to the latest software, but that
didn't fix the problem.

Glenn