Thursday, February 21, 2008

Playing with Freedom Keychain GPS 2000 on Gutsy Gibbon - Part 1

Just received this interesting little GPS receiver from Freedom Input. It is capable of receiving from 51 channels simultaneously. Freedom input sells 2 keychain GPS's. The original Freedom Keychain GPS and the keychain GPS 2000. The first one uses the SIRF III chipset and the latter uses the latest MTK chipset. Sirf III, as, maybe the name suggests is on its third revision, whereas, this is MTK's debut into the GPS world (and I reckon quite a good one). The 2000 version is more compact than the original and has 4 separate indicator lights for the various activities. Some would still prefer the Sirf III chipset, as it has a proven track record. After much brooding I decided to go in for the latter i.e. GPS 2000. Mind it neither comes bundled with any software, but, are supposed to be compatible with popular mapping softwares available.

Now the hard part getting all this to work in Ubuntu. After a hard days night, here is what I got.
In gist this is what I did (apply common sense where stuck)

hcitool scan
sdptool browse
sudo gedit /etc/bluetooth/rfcomm.conf

rfcomm4 {
bind yes;
device <>;
channel 1;
comment “Serial Port”;

rfcomm connect 4
sudo apt-get install gpsd gpsd-clients
gpsd -n /dev/rfcomm4

Basically, we are creating a serial port /dev/rfcomm4 binding to the bluetooth device and then making the gpsd daemon talk to the port. The gpsd daemon then listens and services any requests for the standard GPS NMEA data. And voila..

The picture above shows the satellites that GPS device has latched onto. If it latches onto more than 3 satellites it is able to provide a 3D fix, which means, it can in addition to your position tell you your altitude. I think EPH tells you the horizontal accuracy and EPV tells you the vertical accuracy. Okay, now to get this to work with some freely available mapping software keep checking.

If still stuck check out these links

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