still GPS questions

[Neng-Yu Tu (Tony Tu)]

Hi Michael-

> 2. Is this AssistNOW(TM) supported by the GTA02 software? Are there 
> better/cheaper ways of getting up to date "almanac" and "ephemeris" into the 
> freerunner?
> 

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:

http://people.openmoko.org/matt_hsu/ImplementationAssistNowServerAndClient(GPS.G4-SW-05017-C).pdf

And implementation code in following address.

http://svn.openmoko.org/developers/matt_hsu/agps-online/

Here is a brief script to run this application:
=============================================

#!/bin/sh

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 at u-blox.com

without content and title. And not all mail account are accepted/could 
get reply, I tried openmoko.com account not work but my personal gmail 
works fine.

Since the protocol is pretty straight forward, implement an extra proxy 
   to scale up user should be easy.

And olv has a GPS test program called AGPS UI in following address:

http://projects.openmoko.org/scm/?group_id=127

You could check out and have a try, with "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), 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:

http://alp.u-blox.com/

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

> Other AGPS features seem to rely on gsm communication with a server
> - sending GPS data to that server which helps calculating the position
> - getting additional data about the position from a server
> - even get the precise position measured by gsm triangualtion

For u-blox assist now, you have to provide approximate 
longitude/latitude 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.

> 3. Which of these services are available in a common gsm network in 
> Germany/Europe/worldwide? Can these services be used by GTA02?
> 

The limit from software side of view should same as google map mobile 
version.

Regards,

Tony Tu ( Neng-Yu Tu )