GPS

[Al Johnson]

Gets my location wrong by 100 miles or so. Other GeoIP services put me in 
other locations similar distances away. The BBC has had complaints from 
people reported as being in a different country because it blocks them from 
using the download service. Perhaps this only affects a minority, so it's 
another option to add to the list. If we have multiple sources we can see if 
they agree.

On Monday 07 July 2008, Francesco Cat wrote:
> Another thing that might help: If the FR is connected to any network
> one should also be able to use IP Locator services like
> http://whatismyipaddress.com/ to get another extimation of the
> location of FR. They are usually quite accurate.
>
> Would this help?
>
> 2008/7/7 Yogiz <yogizz at gmail.com>:
> > On Mon, 7 Jul 2008 15:37:08 +0100
> > Al Johnson <openmoko at mazikeen.demon.co.uk> wrote:
> >
> > Thank you for the testing. Keep doing the good work.
> > Hopefully this idea can solve the long fix problem.
> >
> >> First stab uses the example perl functions from ublox for generating
> >> the aid-ini data, replacing their hardcoded x,y,z with values for my
> >> location. The copyright notice on the example code says you can't do
> >> anything with it without permission so I can't give you the script,
> >> but I can tell you how to reproduce it ;-)
> >>
> >> Get the AssistNow online client application note from:
> >> http://people.openmoko.org/matt_hsu/ImplementationAssistNowServerAndClie
> >>nt(GPS.G4-SW-05017-C).pdf
> >>
> >> Create a new script aid-ini.pl and start with:
> >>
> >> #!/usr/bin/perl
> >> print(clientdata_prepare());
> >>
> >> Go to section B - Sample Server implementation and append subroutines
> >> clientdata_prepare and ubx_checksum to aid-ini.pl
> >>
> >> You need to replace the $posx, $posy and $posz values in
> >> clientdata_prepare with some that match your location. These are ECEF
> >> coordinated in m. There's an explanation of the calculation method in:
> >> http://www.u-blox.com/customersupport/docs/GPS.G1-X-00006.pdf
> >>
> >> Alternatively you can use the attached spreadsheet if it survives the
> >> list. Just replace the lat and lon with values for your location.
> >>
> >> You probably want to change the time accuracy to reflect the accuracy
> >> of the Freerunner clock, and possibly the accuracy of your location
> >> estimate.
> >>
> >> Now copy the script to somewhere suitable on the Freerunner and make
> >> it executable. I'm using /usr/local/bin. You need to install perl if
> >> you don't have it already:
> >> opkg install perl
> >>
> >> Switch on the GPS then run the script:
> >> /usr/local/bin/aid-ini.pl > /dev/ttySAC1
> >>
> >> If you cat /dev/ttySAC1 you should be able to see it using the
> >> current time according to your Freerunner. TangoGPS makes it easier
> >> to see what it's doing. In the only test I've managed so far it got a
> >> fix with a poor view of the sky, while my Garmin Geko was still
> >> struggling to see 3 sats. It wasn't quick, but it was better than the
> >> Garmin. It would be interesting if you could try 2 units side by
> >> side, one with aid-ini and one without, to see if it really makes a
> >> difference or if I was just lucky. I'll try to get some more testing
> >> in, but the weather isn't good here, and I don't want to get my new
> >> toy wet ;-)
> >
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