Navigator 5.1- GPS position errors and long acquisition time

julians · Occasional Visitor Joined: May 03, 2004 Posts: 7

Running on a COmpaq 3830 with the official tomtm cable GPS receiver.

I had been running TTN3.x for the past year or so with none of these problems, so I'm pretty sure these issues I'm about to describe are down to bugs in the software, but wondered if other people had noticed the same.

Firstly, if you switch TT on it picks up the GPS signal as quickly as it used to with TTN3 (30secs ish) , no problems here. However if you turn the power to the GPS receiver off but leave TT running on the ipaq (as in when you pull in to get some petrol or something and turn the car off), when you turn the power to the GPS receiver back on TT takes ages to get a lock (10 mins or so), exiting and restarting TT make no difference, neither does resetting the ipaq, you've just got to sit it out.

Secondly, TT seems to offset my position , eg I'm driving up the motorway, but the screen displays my position a distance to the right of the motorway, this doesent happen all the time, just occaisonally. Seems to happen more often when in a town area with lots of close roads. I presume its the 'intelligence' trying to predict which road I'm on when the GPS signal isnt too good. However this never used to happen with TT3. This is quite a problem as in town centres etc (where I most need the navigation), it spends most of its time planning new routes as it keeps thinking I'm jumping from road to road.

alix776 · Posted: Sun Aug 28, 2005 5:49 pm Post subject:

it sounds like a low a signal strength to me not a bug in the software when ever ive seen it happen the signal strength is low have you tried hardwireing the gps receiver to the car have you changed car or moved the position of the gps within the car
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julians · Occasional Visitor Joined: May 03, 2004 Posts: 7

If I used to get this sort of behaviour with tt3, then I would agree with you, that it sounds like low signal strength. But this never used to happen and the only thing that has changed is the software which was upgraded to V5. The position and other installation factors of the GPS receiver are exactly the same as before.

I forgot to mention , I have seen the signal strength meter with 5 bars and still had the second problem.

adventurer · Posted: Sun Aug 28, 2005 10:52 pm Post subject:

I was going to post my own topic on this very subject but you beat me to it.

Ive had tom tom 3, checkpoint, with HP 4150 and a leadtek 9539c see here for pic

http://www.leadtek.com/gps/gps_9539c_1.html

anyway.

No problems what so ever until I updated to TT5.

Today I was in Nottingham and I lost the GPS signal for a short while, not a problem with TT3 and once you get the signal back a few seconds later you are back on track.

But now I lost the signal, the blue direction arrow went off on to one side and locked on to a nearby street and staretd to do an automatic re-route, when the GPS got a proper lock on my correct position it then tried to do a further automatic re-route. All this takes time and in the centre of Nottingham trying to cope with the traffic is not the best time for tom tom to try and keep on doing this auto re-routing all the time.

With TT3 at least you could decide when to do a manual re-route. If you lost your signal you knew that it would be back on the original route in a few moments. Now you have to wait makes up its mind to stop re-routing (It drives me MAD)

I also have a problem where the feed (if thats what you call it) is slow from the GPS.

I seem to be passing points on the road before the blue marker get to them. It that bad I am having to increase my warning times on checkpoint cameras as my alarm goes off after I have passed them, this never happend before.

Any help with these problems will help with my sanity.
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julians · Occasional Visitor Joined: May 03, 2004 Posts: 7

this post here

http://www.pocketgpsworld.com/modules.php?name=Forums&file=viewtopic&t=23851

Exactly describes the second problem I'm having, I think I'll register a support call with Tomtom in the hope that they do something about it.

GrahamCresswell · Occasional Visitor Joined: Sep 09, 2005 Posts: 5

I'm getting the same problem all the time. The TT5 position is constantly about 200 yds NNE of the true position. When I'm driving N or S it generally puts me on the correct road but when I'm driving E or W it is constantly showing me in side streets to the north and re-calculating a route back to the main road. It's almost unuseable.
I'm pretty certain that the GPS is sending the position in WGS84 and I believe that, with NMEA, it is required to do that and the nav software is meant to apply any necessary datum correction according to the map in use. But I've tried OSGB36 as well and it's just the same.

Does anyone have a solution for this or do you know of alternative software to TT5 that allows you to enter an offset.

julianbarker · Lifetime Member Joined: Apr 12, 2005 Posts: 431

IIRC OSGB/WGS84 confusion in the UK usually involve a significant (hundreds of feet) displacement to the east or west. If travelling west or east you are on the wrong road that implies a north/south displacement which must be for another reason.

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