[plug] GPS and maps

William Kenworthy billk at iinet.net.au
Sat Apr 21 08:24:38 WST 2007

On Sat, 2007-04-21 at 00:50 +0800, Bernd Felsche wrote:
> Michael Holland <myk at myk.id.au> wrote:
> >On Fri, 20 Apr 2007, Gavin Chester wrote:
> >> Hey, I know this is way OT and not the sort of geek answer you wanted,
> >> but ever thought of getting good topographical maps, to supplement the
> >> Bib. Track guide, and a compass?? ;-).  Maybe you can exercise the geek
> >> in you by getting an electronic compass ;-)
> >I reckon GPSs should have a small compass built in to the back, by law.
> >To avoid deaths and expensive searches for geeks with flat batteries.
GPS is additional to a compass - but in my experience - I have done
orienteering, map reading (military) and the like, though most of it was
years ago, compasses suck!  Yes they are better than nothing, but when
you are confused, they are often part of the problem, particularly as
sometimes they are subject to external interference.  Thats one reason
why GPS has proven so popular.

> It might be to prove that he was following the track. :-)
exactly - I am within a few meters of THIS spot on the earth/map - and
can reasonably trust it.

> >To get back OnT, has anybody used one of those cheap bluetooth-only GPS
> >units? Any experience with Linux (or java) software that uses them?
> I connected to my TomTom GPS using a Bluetooth USB dongle that made
> it look just like a wired serial (which is, after all that bluetooth
> does; remove the copper between the devices).
> Other than confirming that I'm receiving NMEA sentences, I've not
> done anything substantial (yet).
The one I got is a cheap bluetooth unit.  Works exactly as one would
expect.  lat/log (2D) fixes look accurate, altitude is wildly out
compared to lat/long - its disconcerting to see that you are 10 meters
under water when near subi oval!  This is apparently common in consumer
GPS's - not a real disadvantage in most consumer applications. Ive tried
a few (free/demo) packages for linux and the palm.  State of the art is
it sucks - badly.  Ive settled on cetus for the palm, and gpsdrive for
the laptop.  Cetus isnt a map program like you see in car GPS systems,
but more of a track and location recorder plus electronic compass with
items like speed (my cars speedo is within 1 k or so of the GPS!),
direction (heading, works when walking as well as in the car), true
north, time (can be used to set the palms time) and so on.  I will scan
and register some maps and see if I can get GPSdrive to behave
accurately - takes time I dont have at the moment :(

Oh, and kismet works with it to!  Wardriving - yea!!!


William Kenworthy <billk at iinet.net.au>

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