GPS Satellite Reception Dropout

[rv7boy]

Originally Posted by hevansrv7a

This is from a friend with a Mooney and a 396:

"...the first several thousand 396's had defective antennas. I paid 100 because I didnt want to wait, but if they google the 396, they will find the info reqd to get a new one free from garmin. since i put in my new antenna, i have never lost sat recept."

I received a pm suggesting I check my antenna model number. I found out I have the GA-25 antenna which gave a lot of service problems. I plan to contact Garmin tomorrow to see about getting the newer GA-26. Since it appears to be an antenna problem, I have a few tests in mind as soon as we get some good flying weather here in North Alabama.

My friend's 396, however, seems to have a worse problem. I will direct him to the Garmin reset procedures provided above. Thanks to everyone. I don't have my problem fixed yet, but at least I don't feel alone anymore.

Don

[rv7boy]

Originally Posted by Sam Buchanan

<SNIP>
I can't comment on the Garmin units, but my Lowrance Airmap 1000 with glare shield-mounted antenna has been solid with no reception problems.

But Sam, I've never seen you fly through the "Valley of RF" over near Chapman Mountain. Your dawn patrol always seems to fly around Huntsville's Class C instead of through it.

I'd be interested if your Lowrance has any reception problems going on a nearly straight line from DCU to just north of Moontown. It always happens just before leaving the Class C and tracking apx. 060 degrees between the two "mountains" populated with the TV and radio broadcast towers. I usually fly at 2500 MSL.

I also wonder if any of the other local (DCU and HSV) pilots have had similar problems in that area.

My unit's problems could very well be due to the Garmin GA-25 antenna so I plan to replace it with the newer GA-26.

Don

[Sam Buchanan]

But Sam, I've never seen you fly through the "Valley of RF" over near Chapman Mountain. Your dawn patrol always seems to fly around Huntsville's Class C instead of through it.

Don, I've returned to DCU from Moontown using that route and don't recall any GPS reception problems. Sometimes I'll cut through HSV airspace to make sure the transponder is still working.

The only time I've seen a GPS dropout was when I was flying the old Lowrance Airmap 100. When I installed the Garmin GPS35 receiver (a rock-solid receiver used for driving the iPAQ with AnywhereMap) on the glareshield next to the Airmap antenna, sometimes the Lowrance unit didn't want to play nice with the Garmin. But the Airmap 1000 has never had any problems with the GPS35 running next to it.

[rv7boy]

That's a good data point, Sam. I knew you would reply. I contacted Garmin Tech Support this morning and they explained to me that the GA-25 antenna I have is indeed a more sensitive antenna and is thus more sensitive to RF transmissions from TV, radio and cellphone towers as well as VOR stations. The GA-26 is being sent free, and I will report if I continue to have problems as...

"Yea, though I fly through the Valley of RF..."

Aviation is indeed a continuing education.

Don

[Gary R.]

I have the same problem with my 396. The "LOST SATELLITE RECEPTION" zone is about 4 miles NE of my home airport of Henderson, KY (KEHR). It happens every time I fly through there. It has also happened a couple other times while flying cross-country. It usually doesn't last long but is still very irritating.

[rv7boy]

I thought I would give a little status report for the file archives.

As I posted earlier, I contacted Garmin Technical Support last Wednesday, explaining my problems, and they agreed to send a GA-26 antenna. It arrived two days later via UPS no charge. I haven't flown with it yet, but plan to soon.

Also, my friend contacted Garmin Technical Support last Thursday, and they walked him through the complete reset procedure. He hasn't had a chance to fly it yet, but on a 450 mile round-trip automobile venture last weekend, he said it acquired satellites every time he tried...about 6 times. So he feels confident his problem is solved.

We both are very complimentary of Garmin's Technical Support. They are very courteous and understanding of dorks like me who tend to get bumfuzzled with electrons and electronic gadgets. Give me a button and I can push it, but don't ask me to explain what's going on underneath the button!

I plan to fly my new GPS-26 antenna this week and will (hopefully) be able to conclude this thread.

Don

[MNRVFlyer]

Hi,

I had a similar problem in my 172. I fixed it by installing an external antenna. No dropouts after the install.

[RVadmirer]

Well, I have the new antenna and had the 'lost satellite signal' warning several times during the trip to Memphis and back. I posted the resetting instructions I got and tried the first two which includes a master reset where you lose all your settings and have to put them all back in. I had already downloaded the latest software a few weeks ago. Went flying over northern Cal and on the way back lost satellites again for about 5 minutes. It only sees a couple very weakly and took a long time to come back to life. Will send this feedback to Garmin. They have been very helpful with this and other issues but this one is getting old.......
Dave

[AlexPeterson]

Interesting thread...

I made two round trips last weekend from Minneapolis to Ames, IA (about 190 n.m. each way), and I noticed that my Anywhere Map unit was going in and out of 3D mode, with a few complete dropouts. It probably happened 25 times or more yesterday. I don't recall ever seeing any dropouts before, but, I also was using it as my primary navigation instrument, so I was looking more often at it. (The horrors of what would have happened if I didn't have any GPS - Oh, noooo )

Unfortunately, my 430 is out for the upgrade, so I couldn't compare. But, I've run the Anywhere Map for over three years, and don't recall ever seeing this. It could be the gps unit, of course, time will tell. There is this Notam, which is not supposed to affect us "down low" guys, but it is interesting:

"Minneapolis Center (Farmington MN) [ZMP]: April NOTAM #35 issued by Gps Notam OA [GPS]
Non CIVILIAN GPS May be unreliable or unavailable within a 240 nautical miles radius of 420153N/913847W at FL400 effective from April 24th, 2007 at 07:01 PM CDT (0704250001) - December 31st, 2007 at 06:59 PM CDT (0712312359)"

Wonder what that is all about? The point described is just east of Cedar Rapids, IA.

[az_gila]

Originally Posted by AlexPeterson

.....
"Minneapolis Center (Farmington MN) [ZMP]: April NOTAM #35 issued by Gps Notam OA [GPS]
Non CIVILIAN GPS May be unreliable or unavailable within a 240 nautical miles radius of 420153N/913847W at FL400 effective from April 24th, 2007 at 07:01 PM CDT (0704250001) - December 31st, 2007 at 06:59 PM CDT (0712312359)"

Wonder what that is all about? The point described is just east of Cedar Rapids, IA.

Collins Radio is there.....

Testing of the SAASM has to occur somewhere....

...old press release here, but you can get the point....

http://www.rockwellcollins.com/news/page2905.html

gil A