I should've mentioned that directional is a problem. 6" would be =20 nice, but 1-ft should would fine also. Here's the scenario -- =20 quad-copter in a (large) room with some "obstacles" (partitions, etc =20 to form a maze). We'd like to determine the position of the =20 quad-copter and guide it around the maze (which the "base" will know =20 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 =20 bluetooth (or some other RF transciever) on boad, and it would've been =20 nice to use that, but that does not seem feasible, unless there's some =20 analog way to determine the slight shift in the returned signal. Cheers, -Neil. Quoting Josh Koffman : > On Sat, Oct 23, 2010 at 1:27 PM, PICdude wrote: >> Other than ultrasonic (which is the bulk of the google results), what >> other technologies exist for relatively short (say <100ft) distance >> measurement? =A0It would be nice to use RF (as we'll have some wireless >> comms on the quad-copter), but my quick math tells me that I'd need to >> detect nanosecond differences to get ever 1-ft resolution. =A0Any >> thoughts on this? > > What sort of accuracy do you need? I have a Leica Disto which uses > LASER and gives 1/32" resolution over about 400' I believe. > > The technology has been licenced to others and there are much cheater > options available now. I think Dewalt, and possibly Ryobi make them, > likely amongst many others. > > Josh > -- > A common mistake that people make when trying to design something > completely foolproof is to underestimate the ingenuity of complete > fools. > =A0 =A0 =A0 =A0 -Douglas Adams > > -- > http://www.piclist.com PIC/SX FAQ & list archive > View/change your membership options at > http://mailman.mit.edu/mailman/listinfo/piclist > --=20 http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .