GPS External antenna detect issue / test recipes

Werner Almesberger werner at
Thu May 1 12:54:03 CEST 2008

Andy Green wrote:
> 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.

An attenuation vs. VCONT plot could tell us how close to the abyss
we are with the voltage levels we have there. But we can leave this
task probably to the hardware team in Taipei.

> 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.

Hmm, no other noise sources in the neighbourhood ? From the GPS debugging
efforts I saw in HXD8, I would expect GPS to resent a lack of shielding
rather heavily.

By the way, the antenna switch circuit is identical to what we used in
GTA01. I wonder if anyone noticed usually bad sensitivity there ?

- Werner

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