SPATIAL SPLIT SIMULTANEOUS BROADCAST SYSTEM

摘要

PROBLEM TO BE SOLVED: To allow a user to differentiate two different broadcast contents while avoiding interference. SOLUTION: A sound band signal from sound sources 401 and 406 applies amplitude modulation to an ultrasonic wave from ultrasonic wave oscillators 404 and 409 and the modulated wave is transmitted in air. The original sound band signal is demodulated in air because of the nonlinearity of the air with respect to the ultrasonic wave. Since the directivity of an ultrasonic wave is sharper as the frequency is higher, variable resistors 405 and 410 are adjusted to adjust the ultrasonic wave frequency from the oscillators 404 and 409 so as to decrease the overlapping of the two ultrasonic wave radiation regions thereby allowing the user to differentiate the two broadcast signals depending on the position.