<p>A dual frequency ultrasonic locationing system includes an emitter (106) operable to emit two different ultrasonic frequencies (610-616) simultaneously in one ultrasonic burst (140). A receiver (110) with at least two microphones (116) is operable to receive the ultrasonic burst. A correlator (20) is operable to correlate the signals obtained from each microphone to derive a time difference of arrival of the ultrasonic burst at each microphone. The time difference of arrival of the ultrasonic signal from the emitter impinging on each microphone of the receiver is utilized to determine a location of the emitter.</p>
