FIELD: physics, acoustics.
SUBSTANCE: invention relates to acoustic means of transmitting information using ultrasound. A parametric loudspeaker system comprises a pre-compensator for generating a pre-compensated envelope signal by applying pre-compensation to an input audio signal, where the pre-compensation compensates for distortion caused by in-air demodulation of the modulated ultrasound signal. A pre-modulator, based on a phase signal and a predetermined function for determining the phase signal from an amplitude signal, generates a suppressed sideband signal. A complex signal is generated, having the required bandwidth with amplitude corresponding to the pre-compensated envelope signal and a phase corresponding to the phase signal. A modulator quadrature modulates an ultrasonic quadrature carrier with the complex base-band signal, and an output circuit drives the ultrasound transducer with the modulated signal.
EFFECT: high efficiency of the device with low hardware costs.
15 cl, 5 dwg
