Lost GPS signal with Garmin 296

[mburch]

Originally Posted by Tony Partain

So I did a little research on the 296 and found an issue. Any software version prior to 4.2 has a lower signal resolution. After updating my software the GPS signals are much stronger. It also picks up more satellites that before. So was it the military or was it Garmin? My bet it was Garmin?s software.

FYI, I believe it was only software version 4.00 for the 296 that had the problem, which was fixed in 4.10.

cheers,
mcb

[vlittle]

Originally Posted by markscogg

I had a similiar problem with a Garmin 195 going out in a specific area.
Called Garmin support. Turned out that when I tuned my nav radio to that airport's localizer, the RF took out the GPS.
NOTE: Not transmitting, just receiving that freq took out the GPS!!
This was a known issue for Garmin. Tech support knew several freqencies that were a problem with my radio (Narco). Some were Comm frequencies.
They had a list for other radios as well.

My experience is that the Mark 12D and the 296 are incompatible. The 12D kills my GPS reception, and the GPS interferes with both the RX and TX on the 12D. I contacted Garmin, but had no response at the time.

FYI, the GPSMap III and Lowrance units operated properly.

I don't fly in the interfering aircraft anymore.

Vern Little

[Tony Partain]

FYI, I believe it was only software version 4.00 for the 296 that had the problem, which was fixed in 4.10.

My version was 3. something and the 4.2 made a significant difference in the signal.

[brianwallis]

Well... what does that mean for "us"? For our future GPS purchases... will we be looking for the SAASM stuff? Do we need to be aware of these items in our future equipment considerations and integrations? What will the FAA do about signal degregation with the FAA approved gps approaches? Is this another 7,000$ debacle for "us"? I'm aware of the rule change on ELT beacons as of 2009 to gps encoding.... will the saasm hamper the rescue efforts of future accident victims.... Gentlemen... It's time to get involved... there could be many future ramifications for all of us.
Brian

[lucaberta]

Brian,

Originally Posted by brianwallis

I'm aware of the rule change on ELT beacons as of 2009 to gps encoding

not sure to what rule you're referring to... the 2009 date is the cut-off for support of the 121.5 ELT frequency, but the switch to 406 MHz does not imply that we will be forced to have a GPS capable ELT.

http://www.sarsat.noaa.gov/phaseout.html

Of course, it's best to have a GPS signal fed into the ELT, but as of today, it looks like most ELTs on the market don't yet have such feature.

I'm sure there will be plenty of new products before the Feb 1st 2009 deadline expires.

Bye, Luca

[praterdj]

It just reinforces the need to utilize a chart as a back up while flying. There are many things that can cause a GPS to be unusable.

Glad you didn't have any problems.

[L.Adamson]

Originally Posted by praterdj

It just reinforces the need to utilize a chart as a back up while flying. There are many things that can cause a GPS to be unusable.

Very true, the back up chart should be essiential. But I wonder what the "real" failure rate of picking up a workable GPS signal is? At least in the northern hemisphere with WAAS.

Must be less than a fraction of 1%. I always see a few, who believe that GPS should be utilized as just the backup, and make statements that it's rather un-reliable. I find these statements to be a bunch of baloney.

Of course, if someone has authentic data on the subject, I'd like to see it. In the meantime, I'll continue my avid ramblings for the use of moving map GPS. Preferably with topography data & terrain warning.

L.Adamson --- Garmin 296

[Tony Partain]

Ok sometimes it takes a little time but eventually you get to the bottom of the issue.

First when I did the software update to the GPS my test to see if the signal improved was to pull the plane out of the hanger and turn on the GPS. This produced the results of an improved signal that I was looking for, so I called it a day. But the real issue was still hiding under the glare shield. I went flying again and the GPS signal was degraded again. So I started turning everything off in sequence, all the way down to the master. The master did it, the signal came up to what it was when I pulled the plane out of the hanger to test it. So what the h*%% is it? Sitting on the ground I turned on the master and the GPS then started to move the coil of excess wire and the signal came up again. Thinking the wire was to close to something that was emitting a signal so I moved it. But as soon as my hand was removed the signal came back down. So next I removed the screws from the antenna to try a different placement. When the antenna was placed more than 9 inches from it original placement it would work fine.

So it turns out that the LCD clocking signal from the engine monitor was interfering with the antenna that was placed way to close. When the canopy was down the antenna was with in inches of the screen.

No aliens, no secret government conspiracies or crazy manufacturing problems, just a placement issue. All in all very easy fix by the process of elimination. Of course now I have a hole in the glare shield so I need to finish the leather glare shield cover. It may be flying but its never done.

[praterdj]

Tony,

Thanks for providing the update. This will allow us to build around this in our planes and hopefully avoid this issue. I fly primarily with my GPS but I always track my progress on a chart for back up. It helps to pass the time and keeps me occupied on flights over featureless terrain.