[Openstreetmap] Inner city accuracy
Christian van den Bosch
cjb at cjb.ie
Wed Jan 25 21:39:41 GMT 2006
Lars Aronsson wrote:
> Are some GPS units better than others?
Apparently, recent GPS units based on the "Sirf Star III" chipset are
far better than the previous generation at detecting and locking onto
low-strength signals - I read one review where such a unit sitting in
the cup holder in a car stayed locked onto 8 satellites and gave
something like 4-metre accuracy. With my old Garmin eTrex Vista, I
consider myself lucky to get a fix like that out in the open holding my
unit up to the sky! In a car, I have to put the GPS on the dashboard to
get any worthwhile signal at all. I haven't had a chance to play with
one of these Sirf-based units myself yet though. Soon, my precious...!
> Or should we wait for WAAS or Galileo to give us better accuracy,
> before we can do useful maps of inner cities?
I gather Galileo won't hit showtime till 2008 at least, so I wouldn't
hold my breath on that front. WAAS is slowly becoming more available,
both in terms of regions, and units that support it. DGPS has been
somewhat revived by DGPS-over-IP, but I don't think it'll ever really be
mainstream.
In the meantime, I think all we can do is go down the same streets lots
of times to amass a statistically significant sample set to base our map
drawing on...
Christian / cjb
http://www.cjb.ie/
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