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 --=20 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 --=20 http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .