| 摘要 |
An apparatus and a method of generating a directional acoustic wave. The apparatus has a pre-compensator, an ultrasonic modulator, an amplitude modulator, an amplifier, and a directional ultrasonic beam emitter. The pre-compensator receives an audio signal to perform pre-compensation and then to generate a signal according to an ultrasonic air self-demodulation mechanism selected by a specific design. The ultrasonic modulator provides an ultrasonic carrier wave. The amplitude modulator receives the signal output by the pre-compensator and the ultrasonic carrier wave output by the ultrasonic modulator to load the signal into the ultrasonic carrier wave. The directional ultrasonic beam emitter is used to recover the audio signal by air self-demodulation. The directivity of the ultrasonic wave localizes the self-demodulation within the proceeding path of the wave beam, such that the audible sound carried by the carrier wave can only be heard locally to form the directional acoustic beam.
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