[OSM-newbies] Will the real track please step forward
dv_mlist at verizon.net
Mon Mar 26 04:30:05 BST 2007
Thanks for your response.
On Mon, 2007-03-26 at 01:06 +0200, Dirk-Lüder Kreie wrote:
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> digger vermont schrieb:
> > I have a few tracks I've made by walking around. They make me look like
> > a drunken sailor with the amazing ability to right through blocks of
> > buildings! I've another from driving that looks somewhat better. It
> > actually coincides for the most part with yahoo maps. Is this as good as
> > it gets?
> > I have made some nodes, segments, and ways but at this point I hesitate
> > to upload them because of the accuracy.
> The SirfStar III Chipset has problems in some situations when you walk
> with it, because it trusts speed measurements more than position
> measurements apparently.
Looks like I didn't give full info on the gps units I have. The tracks
I walked were with a Magellan Meridian Platinum. I looked around but
couldn't figure out what chipset it uses. Is it a SirfStar III?
The track made while driving around was the Haicom HI-303E which has an
Evermore chipset. I've had the Haicom for several years now and it took
your reply to jog my memory that the HI-303 had several flavors.
Are the comments you made for the Sirfstar III also relevant to these
> Disclaimer: I have no real knowledge about how the SirfStar III does
> stuff internally, this is based solely upon my own observations of the
> behaviour and some knowledge about GPS measurements in general.
> Due to the nature of the sampling inside the GPS receiver it detects the
> diverse movements of the walking body and extrapolates its next
> positions from it, when the positional data is not accurate enough (only
> 3 sats or bad reception) it even "drifts" in that direction for a bit
> longer than strictly needed, thus generating these "drunken sailor" tracks.
The Magellan I would have thought was designed for slow movements such
Could multipath give these type of results? The houses in the
neighborhood aren't that tall. Three stories and an attic, about
> You'll find that putting the GPS receiver on your back or shoulder and
> cycling to be much more accurate than walking, because the speed
> measurements and the repeated location samples can work together.
I'm going to experiment some and see what I can see.
Thanks again for your thoughts,
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