On 23/10/2010 19:14, PICdude wrote:
> I should've mentioned that directional is a problem.  6" would be
> nice, but 1-ft should would fine also.  Here's the scenario --
> quad-copter in a (large) room with some "obstacles" (partitions, etc
> to form a maze).  We'd like to determine the position of the
> quad-copter and guide it around the maze (which the "base" will know
> about).  We can use two such sensors with an altimeter or three sensors.
>
> Well have GPS on board, but that won't work in a room.  We'll have
> bluetooth (or some other RF transciever) on boad, and it would've been
> nice to use that, but that does not seem feasible, unless there's some
> analog way to determine the slight shift in the returned signal.
>
> Cheers,
> -Neil.
>
GPS isn't anything like good enough on its own.

To use RF you need Static RF beacons in the room and compare phase of=20
coded signal on them. At sensible RF frequency (10GHz) you can't operate=20
6" resolution and less than 100' with an onboard radar. The Copter=20
mustn't transmit on the beacon channels or even near them. 200 pico=20
seconds time difference is roughly 6"

  feed all 3 beacons with same length cable from one controller.

because you can't use TDM (distance too small compared to RF cycles) you=20
need three channels and three receivers on the copter.

you need 3 if full X, Y & Z.

onboard ultrasound "radar" is feasible though and I think simpler






--=20
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