Locationing via phase difference correlation between two frequency pulses derived from a single frequency emitter ultrasonic burst

摘要

Ultrasonic locationing of a tag with an emitter transducer operable to emit a single frequency ultrasonic burst. A receiver with at least two microphones is operable to receive the ultrasonic burst. Each microphone receiver contains two narrowband filters to extract frequencies above and below the ultrasonic burst frequency. A processor derives a low frequency waveform indicative of the phase difference between the dual frequency pulses coming from each microphone receiver. A correlator then determines the time difference of arrival (TDOA) between each microphone receiver by correlating the phase difference waveforms. This invention enables the creation of an ultrasonic locationing system requiring microsecond accuracy on TDOA data, as is necessary with microphone spacing of less than one foot, while using a simple single high frequency emitter source.