Chris lists at
Mon Jul 7 22:33:37 CEST 2008


thanks for your work, but it didn't work for me. I used your spreadsheet 
to calculate the values. Is there something I can do wrong? It sets the 
time, but I still don't get a fix.

$posx = 3784209.3;
$posy = 901525.8;
$posz = 5037577.6;
Are my values for Berlin/Germany (52.516667, 13.416667, h left 0)

Strange thing is, it works great with an external antenna. I usually get 
a fix in less than 40 seconds, the freerunner even stays connected to 
those satellites when I unplug the antenna and holds the fix as long as 
it sees some sky.

Al Johnson wrote:
> On Monday 07 July 2008, Kai Römer wrote:
>> Hi Al,
>> If you need testers, please contact me. I have several gta02v5
>> available and can do tests in Germany Munich.
> First stab uses the example perl functions from ublox for generating the 
> aid-ini data, replacing their hardcoded x,y,z with values for my location. 
> The copyright notice on the example code says you can't do anything with it 
> without permission so I can't give you the script, but I can tell you how to 
> reproduce it ;-)
> Get the AssistNow online client application note from:
> Create a new script and start with:
> #!/usr/bin/perl
> print(clientdata_prepare());
> Go to section B - Sample Server implementation and append subroutines 
> clientdata_prepare and ubx_checksum to
> You need to replace the $posx, $posy and $posz values in clientdata_prepare 
> with some that match your location. These are ECEF coordinated in m. There's 
> an explanation of the calculation method in:
> Alternatively you can use the attached spreadsheet if it survives the list. 
> Just replace the lat and lon with values for your location.
> You probably want to change the time accuracy to reflect the accuracy of the 
> Freerunner clock, and possibly the accuracy of your location estimate.
> Now copy the script to somewhere suitable on the Freerunner and make it 
> executable. I'm using /usr/local/bin. You need to install perl if you don't 
> have it already:
> opkg install perl
> Switch on the GPS then run the script:
> /usr/local/bin/ > /dev/ttySAC1
> If you cat /dev/ttySAC1 you should be able to see it using the current time 
> according to your Freerunner. TangoGPS makes it easier to see what it's 
> doing. In the only test I've managed so far it got a fix with a poor view of 
> the sky, while my Garmin Geko was still struggling to see 3 sats. It wasn't 
> quick, but it was better than the Garmin. It would be interesting if you 
> could try 2 units side by side, one with aid-ini and one without, to see if 
> it really makes a difference or if I was just lucky. I'll try to get some 
> more testing in, but the weather isn't good here, and I don't want to get my 
> new toy wet ;-)
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