GPS External antenna detect issue / test recipes

[Andy Green]

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Somebody in the thread at some point said:
| On Wed, 30 Apr 2008 20:18:45 -0300
| Werner Almesberger <werner at openmoko.org> wrote:
|
|> Andy Green wrote:
|>> To my regret forcing Vcont to 3.0V or 0V when on external or
|>> internal antenna did not make any difference either.
|> There goes the easy way out :-(
|
| What if we just test this part by hooking up a 1.5GHz function
| generator and then measuring output while applying different voltages?

I actually have a 3GHz spectrum analyzer with tracking generator that
can do this.  But it doesn't seem to be the real issue here.

|> Stupid question: did you put the shield back on ?
|
| Well, it needs to be soldered back..

Right, no I didn't put the shield back.  The several extra dB from this
external patch antenna should overwhelm the noise from lack of shield
you would think.  All the other cans are on.

| I have just tried to revive GPS on my GTA02v4 by desoldering the
| antenna switch and hard-wiring the antenna input to the internal
| antenna - with mixed success.
| The GPS is now able to sync to the time and it saw one satellite, but
| reception is much worse than my 2v5. I didn't solder the shield back
| on, though.

Nice test.  The problem is elsewhere despite the Vcont issue.

- -Andy
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