GTA02: NavBoard V3 causing GPS interference

[Dr. H. Nikolaus Schaller]

Am 07.02.2013 um 14:36 schrieb Pascal Gosselin:

> 
> Yesterday I was able to confirm that the installation of the Golden Delicious NavBoard V3 very seriously degrades the performance of GPS when using the built-in GPS antenna.  Getting a 3D fix is taking over 20 minutes on average using the built-in GPS antenna.  When using an external GPS antenna, the issue goes away and an unaided GPS cold start can be achieved in about 41 to 44 seconds.

Or can it be that the U.FL cable for the GPS antenna module is broken?

I know that it is a weak point of the Openmoko antenna module design, but it can be repaired by cutting off the broken end and resoldering. If the cable becomes too short, get a precrimped 100mm U.FL - U.FL jumper cable and cut in the middle.

In that case it could be that after mounting everyting, the LNA of the GPS Module is no longer working and you loose >20dB of
signal amplification.

You can easily check by measuring the DC-voltage at the GPS Module. Or the resistance at the U-FL end of the cable (should read ~50 Ohm).

Nikolaus