[mkgmap-dev] Precision circle

Sun May 24 20:58:05 BST 2009

>
> Usually, there is a blue circle showing on my Vista HCx when the 
> position quality is bad. As more satellites are being located, it 
> grows smaller and vanishes when the positioning is good.
>
> Recently I have observed that a large circle is showing permanently, 
> even when the positioning is very good (+-3 m). In the GPS forum it 
> was mentioned that the behaviour of the circle depends on the map, so 
> I'm asking the question here, too.
>
> Has anybody observed this behaviour? Is there anything during map 
> generation that may influence it?
>
I have observed this behaviour some days ago too. Erroneously I had no 
valid map, but only the 'test-map:all-elements' on my etrex. While 
biking around, I detected that the precision cycle always has an 
constatnt radius of 260m.

I assume this is the precision, where the recalculation started in the 
maps generated with older mkgmap versions. So I assume there is some 
setting in the gmapsupp.img which sets the 'precision' of the map data. 
The higher value from map precision and actual precision gets displayed 
at the circle.