From time to time this subject rises again, so i´m sending these links: http://www.electronics-eetimes.com/en/kickstarter-project-offers-indoor-positioning-on-arduino.html?cmp_id=7&news_id=222924926&vID=209 http://analog-eetimes.com/en/cmos-chip-enables-real-time-location-with-a-precision-of--10cm.html?cmp_id=7&news_id=222905929 Daniel