Low Cost Indoor Positioning SystemCliff Randell, Henk Muller, Low Cost Indoor Positioning System. Ubicomp 2001: Ubiquitous Computing. Gregory D. Abowd, (eds.). ISBN 3-540-42614-0, pp. 42–48. September 2001. PDF, 104 Kbytes.
This report describes a low cost indoor position sensing system utilising a combination of radio frequency and ultrasonics. Using a single rf transmitter and four ceiling mounted ultrasonic transmitterst provides coverage in a typical room in an area greater than 8m by 8m. As well as finding position within a room, it uses data encoded into the rf signal to determine the relevant web server for a building, and which floor and room the user is in. It is intended to be used primarily by wearable/mobile computers, though it has also been extended for use as a tracking system.