Satnav Location incorrect

[peddy]

Hi,

I have the large screen satnav in my car and on Saturday night I was in the Mayfair area, but my Satnav was telling me I was in Saint James's Park and giving me wrong directions. At one point I apparently went over the pond. :rofl:

After I left and got to Oxford street the satnav was correctly showing the streets.

Anyone had this issue?

Pedram

 

[peddy]

In fact, come to think of it, it was wrong from when i configured it to give me directions, and that was from Knightsbridge.

 

[MRol]

Yes I have had this.

I had the whole satnav replaced under warranty, a year ago. Been OK since..... touch wood

 

[EdButler]

This has happened to me twice although not lately - Once was when i did an "Emergency turn in the road" :roll:

I think there is a way to reset it by going into the system menu. To do this: Go into your "Set" or "Settings" menu and HOLD the MENU button for 10 secs.

This will bring you to an 'advanced' menu where i seem to remember some GPS stuff... DONT fiddle with stuff you dont know - it just maybe worth a look to see if theres a 'reset gps' function anywhere. This hidden menu also allows you to enable "Perspective" mode on V27 or later OS's (iirc!)

EDIT: Also make sure that you have at least 3 satellites available in the advanced menu...

Hope this helps!

 

[peddy]

Thanks for the info guys. Will check tonight when i get back home from work.

"Emergency turn in the road" - hmmm... interesting! :driving:

 

[Andy]

Had the battery off mine a few times recently and it's definitely playing up more.

Our Nav uses Satelites obviously but also uses the ABS sensors to give positioning, like when we go through tunnels, etc.

There was definitely a bulletin about this, and it involved taking lots of left and right turns in a city centre which will calibrate it. Best thing I would suggest is keep driving, it will sort itself out most likely.

 

[peddy]

ABS sensors?? don't get how that works?

Yep that's basically what happened I guess. when i left the area in the evening it just seemed to sort itself out once i got to Oxford Street.

 

[MonsterZ4]

When i worked in London we had alot of problems with our Tom Tom, i think mainly due to the height of some of the buildings around us. Do you have problems once you leave central london?

 

[Adam D]

The wheel speed sensors measure the rate of rotation of each wheel which equates to vehicle speed. If gps satellite signal is lost it can extrapolate your position using this suplemenatry data. If you did a u turn without satellite signal I expect it would have a hissy fit as it's expecting you to maintain going along the road in the direction of last known travel.

In London high buildings can interferes with line of sight to the satellites which may have caused a problem similar to the above. I also experienced this when using a road not shown on my mapping disc whilst in France, took a while to settle down once it locked back onto a road it knew.

Adam

 

[peddy]

well that was my first time experiencing the issue and i've not really used the satnav much in last month that i've had the car. there wasn't any expentianlly tall building where i was. maybe 5 or 6 stores high (how many levels is harrods/harvey nics). plus you'd think it would be worse or just as bad on oxford street as there are taller building and the road is not as wide as knightsbridge, but that's where it sorted itself out. (oh god i sound so poncey - mayfair, knightsbridge, harrods, harvey nics...) :lol:

what area(s) of central london do you get the issue usually?

 

[MonsterZ4]

well that was my first time experiencing the issue and i've not really used the satnav much in last month that i've had the car. there wasn't any expentianlly tall building where i was. maybe 5 or 6 stores high (how many levels is harrods/harvey nics). plus you'd think it would be worse or just as bad on oxford street as there are taller building and the road is not as wide as knightsbridge, but that's where it sorted itself out. (oh god i sound so poncey - mayfair, knightsbridge, harrods, harvey nics...) :lol:

what area(s) of central london do you get the issue usually?

It could happen anywhere really where there was densely populated high buildings. The city was a nightmare, but once you got out from the tall buildings it was fine. This is Tom Tom of course though, not BMW Sat Nav.

 

[Andy]

I also think it can use the ABS sensors to spot a change of direction too, ie what Mr Butler was doing

But yes, roughly it would equate to knowing you turned right 90 deg, forward 300yds, left 90deg, etc. It tried to syncronise this with the gps data, so I think after a little while they syncronise and alls gravy.

 

[peddy]

This has happened to me twice although not lately - Once was when i did an "Emergency turn in the road" :roll:

I think there is a way to reset it by going into the system menu. To do this: Go into your "Set" or "Settings" menu and HOLD the MENU button for 10 secs.

This will bring you to an 'advanced' menu where i seem to remember some GPS stuff... DONT fiddle with stuff you dont know - it just maybe worth a look to see if theres a 'reset gps' function anywhere. This hidden menu also allows you to enable "Perspective" mode on V27 or later OS's (iirc!)

EDIT: Also make sure that you have at least 3 satellites available in the advanced menu...

Hope this helps!

OK this happened again last night in Covent Garden area, so again densely populated. As I live in London and would probably mainly use the SatNav in Central London, so I think this will become a pain if it continues. I tried to get to the advance section but it didn't work and the user's handbook has no info about the SatNav. Anyone know where I can get the manual for the SatNav?

Cheers,
Pedram

EDIT: so far on both occasions this has happened when I have started the destination guide as I was in the middle of driving. Could this be the cause?

 

[EdButler]

That shouldnt cause a problem. The Nav also uses your steering wheel direction sesnsor (Presumably linked to the ESP). To re-calibrate, turn the car lock-to-lock a few times. If your GPS module does need replacing, i believe this is fairly easy (seems like a common-ish problem with BMW Mk4 Nav on Google)

 

[peddy]

Ok I found this comment on an X3 forum. When i'm not using the SatNav is it still tracking my position and are my "wheel speed pulses" still calibrated or does this all happen once it's switched on? If the latter then on both occasions when i did turn on the destination guide i was already in a densely populated area....


In dense urban areas like New York, you may loose contact of GPS signals.

Hence the wheel pulse input is vital, and also the calibration of the wheel pulse.

You need to go into the Service Menu, and confirm the following:

GPS almanac downloaded? Good is 'yes'
GPS PDOP value? Good is <2, typical is about 1.5
GPS signal strengths of satellites? Good is between 10 and 15, it will vary from satellite to satellite. I generally have 4 satellites with >10 S/N
Wheel pulses? Must change with speed, and show negative when going backwards.

To calibrate the wheel speed pulses requires good GPS reception, good PDOP, and then a few minutes of constant driving - motorway is easiest.

Don't expect calibration to work in the middle of a city! You need a road in a clear area with unobstructed GPS reception

 

[s18roc]

I get this on a regular basis. I live in central london, but it also happens when i drive out of town. Ive had the entire system, DVD and anatena replaced, but to no avail. I recalibrate the location myself when I am at a junction. Go to Information, then Position Input and type in the road name and the junction you are crossing, then it will work.

 

[lacroupade]

This is standard satnav fare though isn't it? - I've seen it on all three of the last standalone units I've had. Often loses signal in the open for no obvious reason and starts tracking you across a field!

Its always a good idea to sit tight while the satnav acquires satellites as it takes much longer on the move.

Also, units like TomTom and others do require a regular internet connection to 'retune' and enable faster initial satellite location...whether this is because the satellites are not genuinely geo-stationary I don't know, but lordy knows how a car-based units copes with that little foible....

Even the Garmin eTrex, a perfectly good basic navigation unit, but which has no update facility, can take up to 10 minutes in the open to find its position.

 

[gannet]

Only time my TomTom has me going through a field is when Ive been on a new road it doesnt know about....

dont use it much in town though...