I'm working on arduino based project, that actually can perform 3 features: 1. Virtual Touch Screen, for remote control purposes big screen TV, projectors, public display, or for interactive games 2. 3D Ultrasonic Radar, small range - 3 m for now, but real time with update rate 50 fps; 3. Precise distance measurements , down do 12 micrometers. FFT is the major part of software application running on arduino DUE (cortex-3 , ATMEL SAM3X8E), plus 4 very popular ultrasonic distance sensors HC-SR04. Extracting the phase of returning ultrasonic wave, great precision in distance measurements possible. More details on the blog page: http://coolarduino.wordpress.com/2014/08/10/virtual-touch-screen-3d-ultrasonic-radar/ and two demo video clips on youtube channel: http://youtu.be/SpZ_CqVk3e8 Opinions and suggestions are welcome.