Methods and systems for determining a location and an identity of a portable device are provided. The system includes apparatus for transmitting timing synchronization information, a plurality of stationary infrared (IR) base stations and a plurality of portable devices. Each IR base station is configured...http://www.google.com.au/patents/US8139945?utm_source=gb-gplus-sharePatent US8139945 - Methods and systems for synchronized infrared real time location
