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GTA02 using the u-blox 4 hardware and could use u-blox 4 Assist Online GPS A-GPS servces. GTA02 hardware design not comply with official Assist Offline service requirement.
th "A"GPS support could cut TTFF time from 40 secs to 10-20 seconds. And the valid time of assist now download is about 4 hours. You could also check the following address:
http://embedded-system.net/assistnow-gps-services-boost-up-gps-receiver-performance-u-blox.html
Due to the u-blox 4 need to have extra flash to storage up to 14 days of offline data (90 KBytes).
Each download package could have up to 4 hours vaild data to assist TTFF. For u-blox Assist Online, you have to provide approximate longitude/latitude and time to get the corresponds "almanac" and "ephemeris" package. This might be base on application design for how to provide the longitude/latitude. User could select the location area from list menu or world map, or better implementation using the GSM/wi-fi location technique/service.
For GTA02 default shipment image, there is no A-GPS/GPS supported software inside. You could find the u-blox A-GPS online implementation document here:
And implementation code in following address.
Here is a brief script to run this application:
echo 1 >/sys/bus/platform/drivers/neo1973-pm-gps/neo1973-pm-gps.0/pwron
./agps-onlinec -c full -u youraccount -k yourpasswd -la 25.073270 -lo 121.574805 -p 999999.00
cat /dev/ttySAC1
And account application is send a mail to agps-account@u-blox.com
without content and title. And not all mail account are accepted/could get reply. since the protocol is pretty straight forward, implement an extra proxy to scale up user should be easy.
u-blox Assist Offline service could provide up to 14 days of valid assist GPS data in single download package. But Assist Offline service need an extra flash to storage Almanac data, and u-blox 4 will automatically use these data while system start up. GTA02 don't support Assist Offline.
Due to the u-blox 4 need to have extra flash to storage up to 14 days of offline data (90 KBytes), GTA02 don't have it. I would very interested if there is another way to twist it around, but not likely, so far. Offline sample data you could find in the following addesss:
And u-blox did provided source code of Assist offline server implementation and ubx header, you could find it here:
http://people.openmoko.org/tony_tu/src/u-blox
Sample header could be found here: ubx.h
Openmoko projects has a GPS test program called AGPS UI in following address: