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

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

In article ,
Nathan Young wrote:
On Tue, 16 Mar 2004 03:14:29 GMT,
(Glenn Westfall) wrote:

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.

Did you perhaps change the "speed filter" setting on
the setup/system page?

-- ted

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

I just checked mine and I am locking on to 6 satellites with a pretty
decent signal strength. The Accuracy is 48ft and the DOP is 2.1

I am in Okinawa, so maybe the satellites are not as accurate in this
area for some reason. It is just strange that this has only started
in the last week or so. No big deal, it still works fine when I am
moving. However when stopped, since it changes headings all the time,
I don't get an accurate "stopped time" and "moving time" calculation
since it is always moving. I'm about to take a trip to Hawaii, I'll
check it there to see if it gets any better in that part of the world.

Thanks for the comments,

Glenn

On Tue, 16 Mar 2004 07:06:45 -0500, "Dennis O'Connor"
wrote:

It is working perfectly... The erratic motion when standing still is due to
two major items...
One, is the fact that your built in antenna is not recovering the data
stream as consistently as an external antenna will - are you sorrounded by
buildings?... Go out into an open area away from trees and buildings, or get
an external antenna and it will quiet down...
Second, the nature of gps is that there is a circle of confusion around the
fix point... The more satellites your unit sees with consistent data the
smaller the circle of confusion..
When your unit is dithering what is the EPE and DOP showing? I just ran out
to the car to check mine and the EPE is 28 feet, and the DOP is 1.7... The
heading was stable... The altitude was bouncing around about 4 to 5 feet
with variations in the data stream...
Do a google on gps and read up on the technology a bit...

cheers ... denny
"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

I owe you a big THANK YOU!

That was it! I set the speed filter to "Auto" and it fixed the
problem. I guess I changed it inadvertantly at some time.

Thanks again.......

Glenn


On 16 Mar 2004 15:35:18 +0100, (Ted Lindgreen)
wrote:

In article ,
Nathan Young wrote:
On Tue, 16 Mar 2004 03:14:29 GMT,
(Glenn Westfall) wrote:

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.

Did you perhaps change the "speed filter" setting on
the setup/system page?

-- ted

OK, glad it was simple... I had totally forgotten about that option as I
never changed mine from auto... Last night going home I tossed both the 195
and 196 on the dash... Away from the office, with it's over hang roof
blocking half the sky, on both units the EPE was 11 feet and the DOP was 1.0
to 1.1, about as good as it gets, even in the air...
denny
"Glenn Westfall" wrote in message
...
I owe you a big THANK YOU!

That was it! I set the speed filter to "Auto" and it fixed the
problem. I guess I changed it inadvertantly at some time.

Thanks again.......

Glenn


On 16 Mar 2004 15:35:18 +0100, (Ted Lindgreen)
wrote:

In article ,
Nathan Young wrote:
On Tue, 16 Mar 2004 03:14:29 GMT,
(Glenn Westfall) wrote:

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.

Did you perhaps change the "speed filter" setting on
the setup/system page?

-- ted