A hybrid infrared-ultrasound real time location system includes at least one base station having an infrared emitter and a plurality of ultrasound emitters and at least one tag. The tag receives an infrared signal from the infrared emitter and ultrasound signals from the ultrasound emitters and a time difference is determined between the time-of-arrival of the IR signal and the time-of-arrival of each ultrasound signal. Based on the time relationship of the respective transmissions of the IR signals and the US signals, the tag can measure the respective time-of-flight of each of the US transmissions from the US emitters to the tag and compute the distance from the base-station.
