Comand APS 25 m displacement
Thread Starter
Newbie
Joined: Mar 2004
Posts: 5
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From: BARCELONA, SPAIN
E270 W211
Comand APS 25 m displacement
Hi,
I've E270 w211 with Comand Aps with DVD installed on it.
If you see car position in navigation screen, always is 30-40 metres before actually you are. Doesn't matter if you go North, south, east or west.
This error appears even when GPS has 7 or 8 satellites captured.
I read in other forums that there is an automatic adjusment for tyre diameter, but I think it is not enought or simply bad.
Are there any way to fix this problem ? May be with new firmware version ?
Thanks
I've E270 w211 with Comand Aps with DVD installed on it.
If you see car position in navigation screen, always is 30-40 metres before actually you are. Doesn't matter if you go North, south, east or west.
This error appears even when GPS has 7 or 8 satellites captured.
I read in other forums that there is an automatic adjusment for tyre diameter, but I think it is not enought or simply bad.
Are there any way to fix this problem ? May be with new firmware version ?
Thanks
Member
Joined: Nov 2001
Posts: 216
Likes: 1
From: Albuquerque
2003 E320
Actually you are not that far away from the accuracy specification for the non-military users. However the actual results are usually much better than the specification and I would think it would be better than 30 or 40 meters.
One source of error is the receiver itself. The GPS signal does not give a location to the receiver. The receiver must caluclate the postion using timing signals from the different satellites. If the receiver is moving as in the car, the receiver must take this into account as well. (By the way, what happens when you are stopped? Is the location off by 30 or 40 meters then?) In addition, the receiver in the car has maps and after GPS went into use, it was found that many maps were off by a large amount. For these problems, firmware is the only fix.
I would expect the receiver first but there are other things that cause errors as well. The ionosphere's state can be a problem. So can big buildings, towers and the like. Another source could be the satellites but this is probably not the case. For a 2-d location, 95% of the time, the error from the satellites thenselves was about 3 meters for 2003. 3-d, it was about 6 meters.
One source of error is the receiver itself. The GPS signal does not give a location to the receiver. The receiver must caluclate the postion using timing signals from the different satellites. If the receiver is moving as in the car, the receiver must take this into account as well. (By the way, what happens when you are stopped? Is the location off by 30 or 40 meters then?) In addition, the receiver in the car has maps and after GPS went into use, it was found that many maps were off by a large amount. For these problems, firmware is the only fix.
I would expect the receiver first but there are other things that cause errors as well. The ionosphere's state can be a problem. So can big buildings, towers and the like. Another source could be the satellites but this is probably not the case. For a 2-d location, 95% of the time, the error from the satellites thenselves was about 3 meters for 2003. 3-d, it was about 6 meters.
Thread Starter
Newbie
Joined: Mar 2004
Posts: 5
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From: BARCELONA, SPAIN
E270 W211
Dear pfphipps.
When I've stopped the car, the error is the same.
I've tested a Palm with bluetooth GPS and Mapsonic software and seems position is more accurate with error no more than 10 meters.
In cars GPS software takes data from tire advance, this is to avoid loss of data when you are in tunnels. Then, I thing that this data should be adjusted to tire perimeter, and could be this adjustment that is bad now. In my old Audi A6 this parameter could be enter manually by user, but seems that in new mercedes E-class this is not possible. I don't know !!!
When I've stopped the car, the error is the same.
I've tested a Palm with bluetooth GPS and Mapsonic software and seems position is more accurate with error no more than 10 meters.
In cars GPS software takes data from tire advance, this is to avoid loss of data when you are in tunnels. Then, I thing that this data should be adjusted to tire perimeter, and could be this adjustment that is bad now. In my old Audi A6 this parameter could be enter manually by user, but seems that in new mercedes E-class this is not possible. I don't know !!!
MBWorld Fanatic!
Joined: Dec 2003
Posts: 1,917
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From: Torquay, England
E-class E300e Estate, Sprinter (stretched limo)
Re: Comand APS 25 m displacement
Originally posted by jema
Hi,
I've E270 w211 with Comand Aps with DVD installed on it.
If you see car position in navigation screen, always is 30-40 metres before actually you are. Doesn't matter if you go North, south, east or west.
Is there any way to fix this problem ? May be with new firmware version ?
Thanks
Hi,
I've E270 w211 with Comand Aps with DVD installed on it.
If you see car position in navigation screen, always is 30-40 metres before actually you are. Doesn't matter if you go North, south, east or west.
Is there any way to fix this problem ? May be with new firmware version ?
Thanks
Your question has been asked here before.
https://mbworld.org/forums/showthrea...threadid=63425
It might be helpful????
Good luck with the car.
John
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Joined: Dec 2002
Posts: 2,399
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From: Irvine, CA
07 M6, 05 Noble, 01 S4, Smart ForTwo
I had this problem before. Except I would be in an ocean, going wrong direction.. but only had 0 or a few sats locked. They replaced the antenna, COMAND unit, and gateway. Works like a champ now. Good luck with your service dept!!!!
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Joined: Dec 2003
Posts: 1,917
Likes: 14
From: Torquay, England
E-class E300e Estate, Sprinter (stretched limo)
Originally posted by Brav
I had this problem before. Except I would be in an ocean, going wrong direction..
I had this problem before. Except I would be in an ocean, going wrong direction..
Sounds like you read the manual incorrectly If your head was jammed in the door seal, then the car would loose it's watertight integrity and not be suitable for ocean sailing.
John (still laughing over your last post)
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Joined: Dec 2002
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From: Irvine, CA
07 M6, 05 Noble, 01 S4, Smart ForTwo
Originally posted by glojo
Sounds like you read the manual incorrectly
If your head was jammed in the door seal, then the car would loose it's watertight integrity and not be suitable for ocean sailing.
John (still laughing over your last post)
Sounds like you read the manual incorrectly If your head was jammed in the door seal, then the car would loose it's watertight integrity and not be suitable for ocean sailing.
John (still laughing over your last post)
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Member
Joined: Nov 2001
Posts: 216
Likes: 1
From: Albuquerque
2003 E320
I know GPS but do not know how Mercedes has implemented it. The GPS receiver must have some way of continuing for temporary loss of signal for whatever reason but since you see the error even when the car is not moving, I would think this would have little to do with your problem.
It could be the Mercedes maps for your area, it could be the Mercedes algorithm for calculating location, could be a bad receiver or antenna, could be a lot of things. Do you know another person with an idential Mercedes nav system that you can compare with? This might give some insight.
I might add that most people believe GPS is more accurate than it really is. Without some outside source to help it, it can be less accurate than people think. In the USA, there are "correction" transmissions to allow very accurate location for those who need it. This is called "differential GPS" but I do not think the Mercedes receivers use this.
It could be the Mercedes maps for your area, it could be the Mercedes algorithm for calculating location, could be a bad receiver or antenna, could be a lot of things. Do you know another person with an idential Mercedes nav system that you can compare with? This might give some insight.
I might add that most people believe GPS is more accurate than it really is. Without some outside source to help it, it can be less accurate than people think. In the USA, there are "correction" transmissions to allow very accurate location for those who need it. This is called "differential GPS" but I do not think the Mercedes receivers use this.
Last edited by pfphipps; Apr 5, 2004 at 10:27 PM.
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Member
Joined: Nov 2001
Posts: 216
Likes: 1
From: Albuquerque
2003 E320
I do not know if you can enter tire size or not but that does not seem to be your problem so why worry about it?
Using the speed of the car derived from the tire revolutions might help in some cases but other things like direction must be used as well. I suspect anything from tire size changes would be a very small correction in most cases. GPS receivers use other things to achieve the same thing and I do not know if the Mercedes receiver uses tire size or not but I am certain that when you used your Palm, the tire size was not entered into into equation for position. Also, if you have the car receiver has the same error when the car is not moving, entering any tire size cannot make it more accurate.
If you have to worry, worry about the location accuracy, not the tire size correction. Again, I might add, the 30 or 40 meters error is not that unusual for a GPS receiver.
Of course, other things are directly changed by tire size. Two that come to mind would be the speedometer and any kind of miles per gallon calculation.
Using the speed of the car derived from the tire revolutions might help in some cases but other things like direction must be used as well. I suspect anything from tire size changes would be a very small correction in most cases. GPS receivers use other things to achieve the same thing and I do not know if the Mercedes receiver uses tire size or not but I am certain that when you used your Palm, the tire size was not entered into into equation for position. Also, if you have the car receiver has the same error when the car is not moving, entering any tire size cannot make it more accurate.
If you have to worry, worry about the location accuracy, not the tire size correction. Again, I might add, the 30 or 40 meters error is not that unusual for a GPS receiver.
Of course, other things are directly changed by tire size. Two that come to mind would be the speedometer and any kind of miles per gallon calculation.
MBWorld Fanatic!
Joined: Dec 2003
Posts: 1,917
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From: Torquay, England
E-class E300e Estate, Sprinter (stretched limo)
Originally posted by jema
So, are there anybody that knows if it's possible to adjust tire size in Comand APS DVD, or enter to its secret menu ?
So, are there anybody that knows if it's possible to adjust tire size in Comand APS DVD, or enter to its secret menu ?
When your navigation system loses it signal it will calculate a dead reckoning position by movement of the vehicle (through speed and movement left and right. However as soon as the signal is picked up again the system will automatically update itself.
To my knowledge there is no setting secret or otherwise that will allow for a specific tyre size. Sorry about that.
John
