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Mike_T.O.
06-20-2005, 08:14 PM
I have a 645ci with built-in GPS navigation. I have noticed that lately my "tracking" is off by about 50 feet for all streets, off ramps, etc. (i.e. I arrie at the street, address, etc. about 50 feet before the GPS navigation states that I should arrive). Is this a problem with the tracking satellite, or does something have to be "tweaked" in the vehicle?

Thanks in advance,
Mike

playsccr
06-20-2005, 10:55 PM
i have an 04 325i with nav and have the same problem...not sure if its normal?

gojira-san
06-21-2005, 06:59 AM
It may be that you are not receiving enough satellite "fixes" to increase the accuracy. I don't have BMW nav, but if there is a screen that will show you the GPS values, there should be a list of the number of satellites it is using and how well they are receiving. There may also be something that shows the accuracy it is receiving.

I am surprised though that it is 50 feet off - I just used my Garmin on a trip back from the Philly area and I was seeing an error circle of 6-9 feet - and that is with it just sitting on top of the dash - no external gain antenna. Maybe the placement of the GPS antenna in your vehicle is incorrect?

Mike_T.O.
06-21-2005, 07:34 AM
Thanks. I will probably ask BMW what their "margin of error or inaccuracy" is for their Navigation system. It is strange, because when I first got the vehicle, the navigation appeared virtually 100% accurate.

gojira-san
06-21-2005, 08:57 AM
It is strange, because when I first got the vehicle, the navigation appeared virtually 100% accurate.Yeah I would probably ask them to check that the GPS antenna is still mounted in the correct location. If it is below the dashboard and it dropped lower in the car or got turned it would not receive as well. So if it was attenuating the signals, you'd receive less satellites and less signal strength, causing a greater inaccuracy.

Spectre
06-22-2005, 07:09 PM
I am surprised though that it is 50 feet off - I just used my Garmin on a trip back from the Philly area and I was seeing an error circle of 6-9 feet - and that is with it just sitting on top of the dash - no external gain antenna. Maybe the placement of the GPS antenna in your vehicle is incorrect?Presumably your Garmin supports WAAS which really helps the accuracy. I don't know if the current BMW Nav supports WAAS, but the older ones did not, so it's quite possible to get a relatively large error. Plus, with the car attempting to "snap" the reported position to a road, there may be induced errors from the software that are not related to the accuracy of the GPS signal.

gojira-san
06-22-2005, 07:23 PM
Presumably your Garmin supports WAAS which really helps the accuracy. I don't know if the current BMW Nav supports WAAS, but the older ones did not, so it's quite possible to get a relatively large error. Plus, with the car attempting to "snap" the reported position to a road, there may be induced errors from the software that are not related to the accuracy of the GPS signal.True enough. My current Garmin has WAAS, however my old one doesn't and it usually gets down to 15 feet or so. Yeah it could be a software accuracy issue. I just find it funny that my $600 Garmin is more accurate than the NAV in a 6er.