advax at triumf
Jun 26, 2008, 12:28 AM
Post #5 of 6
(2379 views)
Permalink
|
On Wed, 25 Jun 2008, Nils Faerber wrote:
> Using the ephimeris data from ublox a ublox Antaris 5 receiver can have
> a time to first after cold start of less than three seconds!
Now that's impressive! (thanks for the info; I stand corrected re. AGPS
in non-cellphone devices..)
> We already wondered what this GUI is good for ;)
> Choosing your region? Oh well...
From running supld on the command line (it normally runs as a daemon
from startup) :
SUPL daemon version is Mon May 5 12:12:24 UTC 2008
SLP address: supl.nokia.com
SLP port: 7275
A-GPS srv address: supl.nokia.com
Position timestamp: 1214410112.000000
Position latitude: 49.162067
Position longitude: -123.119614
Position uncertainty: 300
Previous A-GPS req time: 0
Previous A-GPS req status: 0
A-GPS support: 1
NW INIT enabled: 0
Cached assistance data support: 1
Packet data for assistance data allowed: 1
Preferred connection id: Rogers Internet
SetId NAI: JohnDoe [at] nokia
PSK EMSK:
Wimax BSID:
GSM Cell ID by BT support: 0
Debug SLP IP source: provisioned
Debug mode: 0
Debug log folder: /media/mmc2/supllog/
agps-ui allows you to choose the "preferred connection id" (it only
offered my EDGE connection), but supld downloaded data over the WLAN.
agps-ui also has a checkbox to enable "Packet data ..". I presume it
means "do you want to incur cellular data charges for downloading an
ephemeris?". I don't know how to turn on debugging (DBUS?); nothing is
written to /media/mmc2/supllog/.
I'm not sure where the positions came from; I suspect from the last
position saved by gpsdriver. It's more accurate than geosearching my ip
address.
I think that supld is exchanging data on DBUS with gpsdriver; the new
version links libsupld.so
I presume from this that some location data is
available from WiMax on the new device, and also from the GPS cell ID. I
know the cell ID is available from my
Nokia cellphone (I had gnokii running on my laptop via USB, and I built
it for the tablet), and I believe Google has been mapping
cell locations by driving around (Rogers told me the tower locations were
confidential when I asked a couple of years back).
Pointing a browser at supl.nokia.com doesn't get you far; I don't know
the path, and it may be using a client-side SSL certificate for
authentication.
I haven't actually tried this much in real life so far. From what you say
about ephemeris lifetime, I would hope to get a 30-second fix going
outside from somewhere with WLAN but no sky (like my home, or office). I
would hope that one could also take an 8-hour plane trip, then use
agps-ui to set my approximate location, and get a fix in a minute or two
instead of "never". If true, it should go a long way to fixing the GPS
woes (thanks, Zoltan).
--
Andrew Daviel, TRIUMF, Canada
_______________________________________________
maemo-users mailing list
maemo-users [at] maemo
https://lists.maemo.org/mailman/listinfo/maemo-users
|
