Lost GPS signal with Garmin 296

[Tony Partain]

I was flying back from Hondo TX on Sunday and my Garmin 296 stopped receiving satellite signals for about 15 minutes. The unit has worked fine for several months. The satellite page was showing a couple of satellites with week signals but would not acquire any more, then about ten minutes later it acquired several and worked fine. The first clue that the signal was fading or being interrupted was the vertical nav feature would stop working. The external gps antenna is mounted on the glare shield and the XM antenna is mounted there too. I?ve used the XM radio several times in the past and it produced no signal problems.

The only thing that has changed is a remote antenna for a XM radio. Has anyone experienced a problem with one of these? Or am I looking in the wrong place? Any suggestions? I called Garmin, but the response was a I dunno.

[Rosie]

Here on the west coast with all the MOAs and Restricted areas, it's very common to see 'GPS unreliable' NOTAMS for areas bounded by certain Lats/Lons. In our case, the GOVT is degrading the signal for purposes unknown to me. We see what you are seeing on a regular basis. Possibly this happened to you.... Rosie

[Bill Dicus]

We've infrequently finished a long cross country without GPS dropout like you experienced. Sometimes it's very brief and sometimes longer. I always assumed it was a deliberate government signal degradation or some other signal problem. We've never identified a problem with the GPS receivers. At least in the areas we fly, it seems it's happening less. Makes you wonder about approaches. Bill

[Brian130]

I bet it had something to do with this... It's from the KZFW, KZAB, and KZHU NOTAMS.

05/005 - GPS IS UNRELIABLE AND MAY BE UNAVAILABLE WITHIN A 330 NM RADIUS OF THE HOLLOMAN TACAN (HMN, 325144N1060633W) AT FL400, DECREASING IN AREA WITH DECREASE IN ALTITUDE TO 280 NM RADIUS AT FL250, 210 NM RADIUS AT 10,000 FT MSL, AND 200 NM RADIUS AT 4,000 FT AGL. THE IMPACT AREA ALSO EXTENDS APPROXIMATELY 230 NM AT FL400 AT THE FURTHEST POINT TO THE SOUTH, DECREASING TO APPROX- IMATELY 110 NM AT 4,000 AGL. 0200-1000 DLY 16 MAY 02:00 UNTIL 20 MAY 10:00

[Tony Partain]

Gentleman thanks for the replies. I hope it was a outside source and not the GPS. Time will tell.

[az_gila]

Lots of testing going on (SAASM)....

This article gives technical details....

http://www.mil-embedded.com/articles/holm/

[rv8ch]

Now I'm starting to understand why everyone and their dog wants to launch their own GPS satellite network...

[tagold]

Tony,

I also experienced this as well, but with a 195. I was Southeast of Temple when it happened. I thought it was strange, but then I thought about it and Fort Hood was not too far away. It didn't happen the rest of my trip. Maybe all of the conspiracy folks are on to something . Stranger things have happened.

Todd
RV-10 #362 (empcone almost complete)

[Tony Partain]

After flying to the Marysville California fly in I had the same problem again with my 296 . Lost or poor signal reception, this time it was over Klamath Falls OR. Signal faded and the GPS lost it vertical nav.
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.

[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.