Tape measure ! Sorry if I didn't somebody else would have... Steve -----Original Message----- From: piclist-bounces@mit.edu [mailto:piclist-bounces@mit.edu] On Behalf Of PICdude Sent: 23 October 2010 18:28 To: piclist@mit.edu Subject: [EE] Distance measurement? Other than ultrasonic (which is the bulk of the google results), what =20 other technologies exist for relatively short (say <100ft) distance =20 measurement? It would be nice to use RF (as we'll have some wireless =20 comms on the quad-copter), but my quick math tells me that I'd need to =20 detect nanosecond differences to get ever 1-ft resolution. Any =20 thoughts on this? Thanks, -Neil. --=20 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 .