GPS receiver problems
 

Hello
My recently bought Garmin 496 has suddenly stopped working. On routes previously driven (in car) I am now receiving only a very small signal. The GPS remains in Aquiring Satelite mode.
Anyone had similar problems with their Garmin?
The battery is full.

It is probably an antena problem I had much the same with a King unit that would drop off line after about 5 min with a MGS about Aquireing satelites.

After much searching the problem was in the antena cable.

Check that the present position is correct, load in nearest airport from database and see if it picks up the signals ok.

Borrow an aerial from someone else, or if you are using an external aerial then put the original one back.

The aerial is powered from the unit and sometimes the connections are not good. Have seen this before with Garmin.

Very difficult to fix, the best option is a new aerial (under warrantee or from ebay)

Sounds like a duff unit. My 496 picks up more satellites than I thought were up there :) within a minute of power-up, as well as EGNOS. The whole thing is more accurate than my altimeter with the right QNH set...

I had this problem with my 296 and Garmin suggested the following solution, which worked:

1. Take the unit somewhere outside, in clear view of the sky.
2. Press and hold the Out button, while you press the On button, and keep the Out button pressed in until you have to acknowledge the "I agree" message.
3. When the power up sequence completes, the GPS page should display "Auto Locate", instead of "Acquiring Satellites". When it does, place the unit on the ground and leave it for up to 30 minutes, until "Auto Locate" is no longer displayed.
4. After this, it should work normally.

Apparently this happens when the unit gets completely lost, so doesn't know which satellites are in its field of view.

Most often the problem I have is turning the GPS on when it is moving (say on a plane, a train or in a car) and then it can take an awful long time to locate anything.

Obviously when it gets lost (say travelling from Surrey to Mid West USA) it gets lost and has to be either manualy "located" or it takes a long, long time to autolocate.

Sometimes I get my 196 out if I am on a train but I think they have something in the windows (esp on Southern or SW trains between London and Portsmouth) that blocks GPS signals as I can never get a signal.

Works OK in the Warrior round Hazlemere .. but not the train.

When I bought a 196 I expected it to locate and get started quicker than my old GPS III but it doesn't.

All

Thanks for the tips. I will try them this evening.

The Gatwick/Heathrow coaches also seem to be very effective at blocking GPS signals. :)

Most often the probelm I have is turning the GPS on when it is moving (say on a plane, a train or in a car) and then it can take an awful long time to locate anything

This is a common problem. AIUI, the GPS has to receive a special packet of data to get started, and this is sent every 30 secs or so. If the reception is being repeatedly interrupted, it never gets it. My car GPS (a cheap Sirf 2 chipset job) locks within minutes if standing still but if one just drives off, it can take half an hour (potentially useless).

I am pretty sure the new trains have metallised windows. On the Gatwick train, I generally cannot get any reception on my GPS PDA.

Be careful with this approach. I can't remember which key it is BUT (for some Garmins at least) if you hold one of the keys down while turning on it returns the unit to factory defaults - including wiping all user waypoints.

OC619

Don't worry, it's definitely not the Out button that does that! I've just checked.

Send it back to Garmin in Romsey. If there is anything wrong with it you will most probably get a replacement withing a week, usually without charge. We use Garmin stuff professionally and you could not hope to find a better company to deal with.

Thanks for eveyones help. I got back from business. Sat it in the garden and ran the Autolocate. It soon captured.

Here's me thinking a GPS would never get lost/confused!

Here's me thinking a GPS would never get lost/confused!

It doesn't - the issue is with getting the initial constellation data, and ensuring good satellite reception afterwards.

If your radio aerial fell off and you couldn't talk to anybody, would you be commenting on it? :)

I've got Memory Map running on a Dell PDA with Dell branded bluetooth GPS receiver. If I move it when it's switched off (ie transport it in my bag to another part of the world), it sometimes takes up to 15-20 minutes to find it's new position.

Switching it off and back on again at the same location, the sats are found much faster. On the sats page you can see it trying various satellite options when it doesn't know where it is.

The Garmin 430 and 496 in the aircraft are very fast in comparison.

It seems like a fair approximation of getting lost, when you switch it on at the location it last knew it was at, but cannot find any satellites, after half an hour of trying. That was what happened with my 296, and probably with ACARS' 496.

Incidentally, one of the enhancements in the 5.20 firmware upgrade for the 296 is "Improved GPS satellite acquisition under certain conditions"!