[OSM-talk] tracing inside town with bad reception was: scanned map -> osm format

[Joerg Ostertag (OSM Munich/Germany)]

> now it sounds like it would be simpler using gps but the problem is
> that most of the ways in the town(s) are narrow and run between
> high-sided buildings - signal strength is nil or gives very bad resolution)

In Munich center i drove all the roads I could get with my GPS and then draw a 
Base-outline-map from this in josm. Uploaded this to osm and made a printout 
with the help of osmarender. This was not too accurate, because I also had 
severe reception problems. But this gave me/us a vague outline for the later 
work. Then I took my Rollerblades, a writing board, a set of pencils and the 
printouts, went there again and draw all the streets inside the interesting 
area by hand almost without gps reception. For this I was 'only' estimating 
the distances between the buildings/streets. But because I now had the 
outlines, it was not really difficult, since all the distances could be 
estimated by mostly doing something like:
 "in this part we have 4 roads, so we divide the distance between 
  the main roads by 4"
The results where pretty good and I didn't need any scanned maps.

You might think about this alternative.

Some other things we found which sometimes improves reception/track 
quality are:
 - try different receivers (if you get a chance to)
 - wait at each point where you have reception until 
   your receiver found all the Satellites it can find at this spot.
 - Entering into a narrow road just go on very fast. If you're still
   moving some receivers can get more information from a moving signal
   (once it had a GPS-lock) , than from a still standing. This is due to
   "frequency-shift-measurement".
 - If you have a street with bad reception, try to drive through from both
   sides if possible.

-

Joerg

PS.: I'm currently also looking for really good GPS-Antennas. So if anyone has 
good hints for really good but affordable GPS-Antennas. Any hint is welcome.