Navteq software DGPS?

RoyB · Occasional Visitor Joined: Aug 17, 2004 Posts: 3

The way my TCM PDA with navteq software (Medion) works suggests that it is not entirely a stand-alone GPS output. I believe the output is corrected with direction and map matching software.

I first noticed this when I ignored the 'short' right turn and continued on the main road. The PDA immediately assumed it was wrong and jumped me onto a track the other side of a ditch. Interesting.

Today, the clincher, I was driving off road when I passed over a road on the PDA. It immediately executed a turn and jump onto a metalled road 25 metres from my present position. I continued on my path and the PDA on its until the positions deviated by about 150 metres. At this point it gave up and showed a zigzag back to my present position. As the departure increased it simply marked my position.

Cross checking, on another occasion, with a Magellan 315, there was a 7 second (about 140 metres) difference East. I will be checking both against a guaranteed position in a day or so.

What I have also noticed is that submitted POI occasionally fall away from the road. Does anyone have any confirmation on how the system works? Does this make it a DGPS?

lbendlin · Posted: Tue Aug 17, 2004 9:40 pm Post subject:

Welcome.

NAVTEQ does not write software. They provide raw maps. Your software is Navigon (rebrabded under Medion).

DGPS is a function of the receiver. What you experience is "snap to road", a feature (some say a bug) in the software.
DGPS makes your position more precise, and doesn't get it wrong.
Snap To Road tries to guess where you are (assuming you MUST be on a road), and sometimes does get that wrong.
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Lutz

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RoyB · Occasional Visitor Joined: Aug 17, 2004 Posts: 3

Lutz, 'snap to road' nice term. Thanks.

lbendlin · Posted: Wed Aug 18, 2004 11:07 pm Post subject:

Not my invention - that's what they use. Some programs (like Mapopolis) do actually allow you to switch that off.
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Lutz

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