This tutorial will guide you through the steps required to share your Nokia N95s built in GPS with your laptop, in Linux.

1. First you need to grab a copy of ExtGPS. Symarctic ExtGPS is free for personal, non-commercial use. You also use the Mobile Code below to download it.



2. Now that you have ExtGPS installed, you can find it by choosing Menu -> Applications -> ExtGPS. You will be prompted to allow ExtGPS to use connectivity applications and to allow ExtGPS to use positioning data. Choose Yes for both.

 


3. It may take quite a while before the GPS starts to receive a valid signal and get a fix. Make sure you are outside and have a clear view of the sky. The satellite icon will change from red to green once it has a fix.

 

4. Make sure your phone is discoverable via Bluetooth. Choose Menu -> Tools -> Bluetooth. I chose to make my phone visible for 5 minutes.

 
 


5. The next few steps are done from the command line. Here’s what I had to do on my Fedora 9 system.

   [user@radon ~]$ sdptool search SP
   Inquiring …
   Searching for SP on aa:bb:cc:dd:ee:ff …
   Service Name: Data Transfer
   Service Description: Version
   Service RecHandle: 0×1000f
   Service Class ID List:
   “Serial Port” (0×1101)
   Protocol Descriptor List:
   “L2CAP” (0×0100)

   Service Name: Symarctic ExtGPS
   Service Description: Share phone’s built-in GPS module via Bluetooth
   Service Provider: Symarctic Solutions
   Service RecHandle: 0×10019
   Service Class ID List:
   “Serial Port” (0×1101)
   Protocol Descriptor List:
   “L2CAP” (0×0100)
   “RFCOMM” (0×0003)
   Channel: 5
   Language Base Attr List:
   code_ISO639: 0×656e
   encoding: 0×6a
   base_offset: 0×100

6. The above output shows your phones Bluetooth MAC address, and that ExtGPS is exposing a serial port on Channel 5. We need to bind these together to make an entry in /dev.

   [user@radon ~]$ sudo rfcomm bind 1 aa:bb:cc:dd:ee:ff 5

7. The rfcomm bind paramaters above are the rfcomm device number, the phone’s Bluetooth MAC address, and the channel number as reported by sdptool. This creates a serial port at /dev/rfcomm1.
8. At this point you should be able to stream raw NMEA sentences from your N95 directly to the console:

   [user@radon ~]$ sudo cat /dev/rfcomm1
   $GPGGA,022314.000,4826.67566,N,12322.19605,W,1,07,1.9,13.7,M,-18.3,M,,*52
   $GPGLL,4826.67566,N,12322.19605,W,022314.000,A,A*4A
   $GPGSA,A,3,30,29,10,21,24,26,15,,,,,,2.9,1.9,2.2*3D
   $GPGST,022314.000,8.8,13.0,6.1,65.6,7.1,11.1,14.0*63
   $GPGSV,3,1,11,05,09,179,,02,10,072,25,30,28,194,38,29,77,118,42*72
   $GPGSV,3,2,11,10,42,059,36,16,24,315,27,21,45,256,43,24,84,024,40*79
   $GPGSV,3,3,11,18,14,198,,26,10,114,38,15,09,128,33*49
   $GPRMC,022314.000,A,4826.67566,N,12322.19605,W,0.1,159.6,151008,18.1,W,A*3B
   $GPVTG,159.6,T,177.7,M,0.1,N,0.3,K,A*2C
   ^C

   While the NMEA sentences are streaming to the console, the Bluetooth icon in ExtGPS should change from red to green.



9. We’re now connected so let’s do something a bit more useful. First, let’s run gpsd on the computer.

   [user@radon ~]$ sudo /usr/sbin/gpsd -N /dev/rfcomm1

   The -N paramater tells gpsd not to switch to background mode. I prefer doing it this way as I don’t leave gpsd running all the time. I only run it when I want to use it, then just hit ^C to close it. See the gpsd man page for more options.

10. Now, from a second terminal window, try running xgps.

    [user@radon ~]$ xgps

    You should see something similar to the following:


click to enlarge

11. xgps is showing the usual GPS data. Latitude, Longitude, Altitude, Speed, etc.
12. There are a number of applications available in Linux that can take advantage of a GPS device. I like using a combination of Kismet and GPSDrive while wardriving. If there is enough interest, I’ll write a tutorial on how I wardrive with Kismet and GPSDrive.