GPS loss of signal explanation

I think its usually a software problem. I've had various issues with
losing signal in different scenarios with my Garmin handhelds and
Garmin has always provided me a ROM update which appears to address the
issue.

-Robert


Jay Honeck wrote:
http://www.scn.org/~bk269/gps.html

This is an interesting site that explains why some pilots (seemingly
mostly running Garmin-brand portable GPS units) are having trouble with
losing satellite lock.

So far I've not had any trouble with our new 496 (and I've never had
any trouble with the Lowrance or AvMap units) -- but it's nice to find
an actual explanation for a problem that has struck several folks on
this group.

Robert M. Gary wrote:
I think its usually a software problem. I've had various issues with
losing signal in different scenarios with my Garmin handhelds and
Garmin has always provided me a ROM update which appears to address the
issue.

I agree. The most recent rash of reception problems is very likely a
firmware issue because it's happening to too many people with units of
varying age. One guy in this group reported the problem on his (then)
new unit, while mine was about 6 months old at the time. No way those
units are of the same manufacturing batch.

As further evidence, I reset the almanac to no avail, and when the
receiver went totally deaf in the airplane a couple months back, I hit
the avionics power off for 30 seconds. No difference. While I admit
the IF radio interference issue is real, this particular problem doesn't
have anything to do with that.

I have an email into Garmin tech support asking whether I'll wedge the
box by downgrading to 2.4 (the version it came with), 2.6, or 2.8 in an
effort to determine if firmware is indeed at fault. Can't wait to hear
their answer. It better be a good one.

-Doug

--------------------
Doug Vetter, ATP/CFI

http://www.dvatp.com
--------------------

"Doug Vetter" wrote:

I agree. The most recent rash of reception problems is very likely a
firmware issue because it's happening to too many people with units of
varying age. One guy in this group reported the problem on his (then) new
unit, while mine was about 6 months old at the time. No way those units
are of the same manufacturing batch.

If it's a firmware issue, wouldn't you expect *everyone* to be having
problems?

Through almost a year of revisions, my 396 was always solid. Others have
reported the same.


--
Dan
C172RG at BFM

Dan Luke wrote:
If it's a firmware issue, wouldn't you expect *everyone* to be having
problems?

Not necessarily. Firmware is often used to handle discrepancies between
various revs of the hardware so the end-user experience is identical
across those revs, and a fix for one version may cause problems on
another (or only a few of a given batch if they have poor parts tolerances).

I just find it interesting that my system was functioning normally for a
good six+ months in all sorts of conditions (hot and cold) and then it
just started freaking out. Could it be hardware? Certainly. But based
on what I've seen in my time as am embedded systems developer, nine
times out of ten, problems like this can be traced to a software error
(never mine, of course) :-)

-Doug

--------------------
Doug Vetter, ATP/CFI

http://www.dvatp.com
--------------------

Dan Luke wrote:
"Doug Vetter" wrote:
If it's a firmware issue, wouldn't you expect *everyone* to be having
problems?

No, in fact one of my problems didn't happen until after 200 hours of
use. It was just a specific scenario in the software that happened to
be tickled. Its just like when you PC locks up, you'd think everyone's
PC should be locking up but your scenario is different. Perhaps a
couple sat's came in at just the right (or wrong) strength and the unit
hit a part of the software that was coded wrong.
-Robert

I have a full Narco stack in my Cherokee and keep the antennae for my Garmin
196 just to the left side of the windshield brace. I've never have seen a
problem with the GPS in the past 5 years.

This spring I upgraded the radios to the 12D+ package with the same results.

Mike

"Jay Honeck" wrote in message
oups.com...
http://www.scn.org/~bk269/gps.html

This is an interesting site that explains why some pilots (seemingly
mostly running Garmin-brand portable GPS units) are having trouble with
losing satellite lock.

So far I've not had any trouble with our new 496 (and I've never had
any trouble with the Lowrance or AvMap units) -- but it's nice to find
an actual explanation for a problem that has struck several folks on
this group.
--
Jay Honeck
Iowa City, IA
Pathfinder N56993
www.AlexisParkInn.com
"Your Aviation Destination"

mbremer216 wrote:
I have a full Narco stack in my Cherokee

My deepest sympathies.

-robert

"Robert M. Gary" wrote in message
ups.com...

mbremer216 wrote:
I have a full Narco stack in my Cherokee

My deepest sympathies.

-robert

LOL! For the Narcos or the Cherokee -- or both...
That was cruel, I'll take it back. Hehehehe....

I don't know why...I've never had a lick of trouble out of any of it.

Mike
"Robert M. Gary" wrote in message
ups.com...

mbremer216 wrote:
I have a full Narco stack in my Cherokee

My deepest sympathies.

-robert

I don't know why...I've never had a lick of trouble out of any of it.

Atlas has two Narco coms, a Narco DME, and two Narco GS/VORs. All work
perfectly, all the time.

I've not quite figured out where the anti-Narco sentiment come from,
but it's almost as insidious as the anti-Microsoft attitudes out there.

--
Jay Honeck
Iowa City, IA
Pathfinder N56993
www.AlexisParkInn.com
"Your Aviation Destination"