US Patent 8139945 Methods and systems for synchronized infrared real time location

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 to receive the timing synchronization information and to transmit a corresponding IR location code in a time period based on the received timing synchronization information. Each portable device is configured to: 1) receive the timing synchronization information, 2) detect the IR location codes from the IR base stations and 3) transmit an output signal including a portable device ID representative of the portable device and the detected IR location code. Each portable device is synchronized to detect the IR location code in the time period based on the received timing synchronization information.