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The smartphones contain an integrated GPS receiver. The devices used are marketed as Assisted GPS ('AGPS'). Performance requirements are defined in GSM/GPRS 3GPP TS 25.171, CDMA 3GPP2 C.S0036-0. There is some discussion available as to what significance that "A" might have.
The external antenna for the GPS uses an MMCX connector. More information about external antennas on the GPS antennas page. The connector for the internal GPS antenna also uses an MMCX connector. The external connector is located on the side of Freerunner.
The two current models (Neo 1973 and Neo Freerunner) use different GPS chipsets. The Neo Freerunner GTA02 GPS device contains the u-blox ANTARIS 4 ATR0635.
A critical problem with early (current) GTA02s is that accesssing the SD card generates RF noise, which causes very long TTFF (time to first fix) (10min+ or longer). See this page for more discussion and suggested fixes. Using an external antenna is one.
Main article - gllin
The GPS driver is available here: http://3rdparty.downloads.openmoko.org/gllin/. It is a command line tool that after starting writes the positioning data so that they can be read as if they were written to the file.
And here the Mail from Michael Shiloh http://lists.openmoko.org/pipermail/community/2007-November/011916.html
There was an effort to write a Free Software program that could be used instead of this binary-only program, but this stalled after the decision to change GPS chips in GTA02. The Iphone 3G also uses the same GPS chip. It's not inconcievable that this might lead to further effort.
See Hammerhead/Protocol for details and the latest status.
Some scripts for those with the binary are on Manually_using_GPS
Please see the important information on Gllin!
To turn on the GPS, echo 1 to the file /sys/devices/platform/s3c2440-i2c/i2c-adapter/i2c-0/0-0073/neo1973-pm-gps.0/pwron
To read from the GPS, simply read /dev/ttySAC1.
gpspipe -r 127.0.0.1 2947
gpspipe is in package gps-utils
NOTE:
cat /dev/ttySAC1 Produces the unknown msg*58 this doesn't happen with gpspipe |
Before getting a fix, the GPS spits out lots of "$GPTXT,01,01,01,NMEA unknown msg*58", though these stop once a fix is obtained.
A position without a fix looks like:
One with a fix:
0515,*7A
(central Scotland)
--Speedevil 11:52, 7 April 2008 (CEST)
If you are having GPS problems with your Freerunner, please document them on the page GPS Problems. FreeRunner GPS antenna repair SOP documents a possible solution.
In Openmoko projects, you will find a GPS test program that provides graphical and text dump of GPS information. See Howto Test Your GPS with agpsui. The project is called Openmoko AGPS UI project.
As people develop more sophisticated GPS applications, please note them here.
Here are some ideas for possibilities:
This procedure depends upon being able to set up a network connection between your Neo and your laptop. The connection can be over either WiFi or USB cable.
First be sure you have gllin and gpsd installed on the Neo. Some Neo Freerunner images don't have them, they use a different GPS stack called gypsy.
Tested with RoadNav. Works great!
If you have an unlimited GPRS data package you could make your gpsd service accessible over the Internet. This opens up many possibilities. For example, you could implemented AVL (Automatic Vehicle Location) by having a web server somewhere query your gpsd server for your position and write it to a KML file which would then display your location on a Google map.
To make your Neo appear like a regular Bluetooth GPS: