Inaccurate GPS location

[fogeychat]

My TomTom was bought at the end of 2012 and used mainly by street names or post codes....Fine. In February of this year I travelled to Spain, only to find that when identifying a location using GPS Co-ordinates, the indicated position is some 20 miles away from where I know it to be. Make the thing almost useless!

 

[canderson]

You'd have to give us some specifics regarding what you did in the way of coordinate entry before "useless" is going to mean much.

Please identify the coordinates you used, which of the three coordinate systems you used ('dd.mmmmm' or 'dd mm.mmm' or 'dd mm ss') and where you expected to be taken.

I use coordinate entry on all of my units nearly every time I'm out, and have never been misled. Most of the time, it's a simple misunderstanding about the possible coordinate formats, and once that's settled, things are good again.

 

[Andy_P]

A few metres out?... Maybe
(due to different map datums in use and general inaccuracies)

But 20 miles? That surely has to be a mistake or misunderstanding of some sort?

 

[canderson]

Yeah, this won't be a datum issue, it will be a coordinate formatting issue. A datum issue can throw you off by a hundred meters or more, but not 20 miles.

I've found that people who don't use it regularly can be confused by the fact that the TomTom will accept coordinate data in 3 different formats, and don't realize that the entry method has to be precise. For example, if the coordinates are specified in deg/min/sec (e.g., 40º26'13"), sometimes people will try to enter it as 40.2613, etc. on the TomTom. That throws things severely out of whack.

 

[Andy_P]

Too true....

 

[Arno]

Let's not forget that all of Catalunya lies to the east of the Prime Meridian.
Could there have been a possibility that the location was out by 10 miles to the wrong side of longitude 0 ?

Remember the little mistake I made in a reply to Steven, ending up to the east of Kings Lynn.

 

[canderson]

Certainly possible, but since the TomTom uses pretty specific notation for this (E and W, not just a "-" sign for west as some systems use), it wouldn't be a simple entry error, it would be a lack of knowing where you were. Anything is possible, I suppose. The OP has never returned to give us any clue as to where he was so we could check any of this out.

 

[Arno]

Certainly possible, but since the TomTom uses pretty specific notation for this (E and W, not just a "-" sign for west as some systems use), it wouldn't be a simple entry error,

I thoroughly disagree.
How the heck do you think I goofed up with Kings Lynn,
The default for us in North America is the upper left quadrant and I never enter a coordinate letter.
I hate tapping around on that inaccurate GO 1535 (need your screen shift correction there!) so I just inch backwards until I can leave as much as possible untouched.

If the OP came from Madrid, the car ferry in Bilbao or what have you, he could have goofed up like I did.

It would be nonsense for me to say "that caused it" I just wanted to mention that as a possibility.

 

[canderson]

Have you ever wondered why you don't need to include the N or the W? Why they're already in place?

 

[Arno]

Does that apply to UK, French and Spanish Europeans too?

 

[canderson]

Yup. Turns out it's simply a question of where you've been.

 

[LisaB]

New to the forem,

We have an integrated Carminat system in a Renault Kangoo (van). Since mid December it has been showing an incorrect current location. We are in SW Devon but the system shows Wales. I have updated the sd card, done a quickfix but it still does not work. I have done "the delete the ephem file" on the sd card and computer and then re-installed it with no luck. I re-set the unit to orginal factory setting reinstalled the original card and NOTHING! I finally replaced the sd card with one from another Renault van and the problem persists..

I don't believe it is the sd card but the integrated system itself. Any ideas? Thanks

 

[canderson]

Not that it necessarily helps, but is your description saying that the error is strictly along N/S lines, and that your E/W position is correct?

 

[LisaB]

Don't know what you mean by N/S lines or the E/W position... but as I am parked in my driveway (aka home setting)... when I route to go home, the devise tells me that it'll take 199 miles to get there. All routes start somewhere in Wales.

I have gone so far as to remove the fuse, idled the car for a while, shut the car off for 10 minutes, restarted, replaced the fuse, re-installed the sd card and still nothing.

I have searched through youtube and cant find anything that helps. I did however find a video of an external tomtom with a similar problem (gps location was close but not on the exact road) and they did a manual re-boot which fixed the error.

 

[Arno]

canderson's question refers to the earth coordinate system.

This 'somewhere in Wales', is it exactly north in a straight line from your actual position in Devon?

 

[canderson]

Yes. I am asking whether or not the device seems to have the longitude spot on, but always errs only in latitude.