In message <01bd2a4e$1a38aee0$66010128@baby>, Peter Neubert writes >Get hold of an elastic fiber optic cable (if it has been invented) meassure >the time it >takes to send a pulse and Voila you got the distance :-) The VPL DataGlove (used in virtual reality applications) used fibre- optic cable to measure finger flexion, with an IR source at one end and a sensor at the other end. They made small cuts in the fibre-optic cable, so that the IR transmission varied as the finger was flexed. Rather crude, but it worked reasonably well. Leon -- Leon Heller: leon@lfheller.demon.co.uk http://www.lfheller.demon.co.uk Amateur Radio Callsign G1HSM Tel: +44 (0) 118 947 1424 See http://www.lfheller.demon.co.uk/dds.htm for details of my AD9850 DDS system. See " "/diy_dsp.htm for a simple DIY DSP ADSP-2104 system.