Happy New Year All,

Recently, I have noticed the all of my "Marked" placed have drifted off location about 300 feet South. For example, I marked a friends house about 6 months ago, I go back about 3-4 times a month and was dead on with each visit. I returned over Christmas and now the marked spot is now across the street to the South. So, I checked my other marked locations only to discover they are off as well.

The vehicle location appears to be close to the exact location on the display. I have also verified the Long/Latitude to what the NAV's location and it appears really close. The NAV has always indicated "GPS".

Could going from a warm garage (70's) to colder outside air (upper 30's) effect the NAV? Is there a process to "reboot" the NAV?

 

try taking out the Navi CD and put it back in

 

That's really bizarre. So you are saying that the car location is correct wherever you go, but your marked points of interest have changed location?

All navigation systems have "map match" algorithms. They take as input the GPS reported location of the vehicle, and do an intelligent search of local streets to see which one you appear closest to, and sticks your car icon right on the street. The algorithm usually takes into consideration your previous raw and "map matched" location when deciding on a new location.

My point? It sounds like perhaps the marked places are showing your GPS reported location, and not the map matched location, assuming that you marked those places using the current vehicle position and not by directly entering them on the map.

I don't think the temperature difference is going to affect the GPS system. The wrong kind of tint will though.

 

The nav systems also use an assumption that all neighborhood blocks are of the same length. We all know they are not, but that might cause the actual location to be different from the maps assumed location.

 

Thanks for the replys. I decided the just delete the marked entries and then re-add them as I go. I'll get my GS serviced if they drift again.

The windows have been tinted since the end of May '05 but recently started to notice the entries issues. Took out the NAV DVD, checked it and then put it back in with no differences.

I need to reference the GS manual about the GPS calibration but how would one go about finding a correct GPS ground location for calibration?

 

You can use an intersection to calibrate your nav system. It usually self corrects and calibrates itself though. GPS uses satellite time reference signals to compute its own location. Sometimes when driving the map data and the GPS will vary and the car icon will appear outside of the road. It eventually will snap back. Marked Points ( older name ) are supposed to stay put however. This would be a good way to use the Latitude Longitude coordinates that the system generates. Write down the coordinates the next time you mark your friend's house and then later see if you can input them on page two as Lat, Long. and see if they coincide. Do you have any other "old" locations that have moved? How about the Previous Destinations? Are there any objects near the Nav system that could deflect the signal? Have you been travelling at or near the speed of light?

Rock