Audio apparatus
First Claim
1. An audio apparatus comprising a modulator for modulating a first ultrasonic signal with an audio signal to provide a second ultrasonic signal lying within a first frequency range;
- a transducer for converting the second ultrasonic signal into an ultrasonic pressure wave for transmission into a non-linear medium to allow demodulation of the ultrasonic pressure wave and thereby generate an audio pressure wave representative of the audio signal wherein the transducer has conversion characteristics that determine how an amplitude of the ultrasonic pressure wave varies with an amplitude of the second ultrasonic signal across the first frequency range;
processing means for modifying the audio signal to compensate for the demodulating properties of the non-linear medium; and
means for modifying the audio signal to compensate for a variation, with frequency, of the conversion characteristics of the transducer across the first frequency range.
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Accused Products
Abstract
An audio apparatus comprising a modulator 12 for modulating a first ultrasonic signal 29 with an audio signal to provide a second ultrasonic signal 30; a transducer 15 for converting the second ultrasonic signal 30 into an ultrasonic pressure wave for transmission into a non-linear medium to allow demodulation of the ultrasonic pressure wave and thereby generate an audio pressure wave representative of the audio signal 29, processing means 11 for modifying the audio signal to compensate for the demodulating properties of the non-linear medium; and means 8 for modifying the audio signal to compensate for the conversion characteristics of the transducer 15.
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Citations
21 Claims
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1. An audio apparatus comprising a modulator for modulating a first ultrasonic signal with an audio signal to provide a second ultrasonic signal lying within a first frequency range;
- a transducer for converting the second ultrasonic signal into an ultrasonic pressure wave for transmission into a non-linear medium to allow demodulation of the ultrasonic pressure wave and thereby generate an audio pressure wave representative of the audio signal wherein the transducer has conversion characteristics that determine how an amplitude of the ultrasonic pressure wave varies with an amplitude of the second ultrasonic signal across the first frequency range;
processing means for modifying the audio signal to compensate for the demodulating properties of the non-linear medium; and
means for modifying the audio signal to compensate for a variation, with frequency, of the conversion characteristics of the transducer across the first frequency range. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
- a transducer for converting the second ultrasonic signal into an ultrasonic pressure wave for transmission into a non-linear medium to allow demodulation of the ultrasonic pressure wave and thereby generate an audio pressure wave representative of the audio signal wherein the transducer has conversion characteristics that determine how an amplitude of the ultrasonic pressure wave varies with an amplitude of the second ultrasonic signal across the first frequency range;
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12. A method for transmitting an ultrasonic pressure wave into a non-linear medium for demodulation comprising:
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modulating a first ultrasonic signal with an audio signal to provide a second ultrasonic signal; converting, using a transducer having conversion characteristics, the second ultrasonic signal into a ultrasonic pressure wave for transmission into a non-linear medium for demodulation and consequent generation of an audio pressure wave representative of the audio signal; modifying the audio signal, before modulating the first ultrasonic signal, to compensate for the demodulation properties of the non-linear medium; and modifying the audio signal, before modulating the first ultrasonic signal, to compensate for the conversion characteristics of the transducer.
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13. Audio apparatus comprising a modulator for modulating a first ultrasonic signal with an audio signal to provide a second ultrasonic signal lying within a first frequency range;
- a transducer for converting the second ultrasonic signal into an ultrasonic pressure wave for transmission into a non-linear medium to allow demodulation of the ultrasonic pressure wave and thereby generate an audio pressure wave representative of the audio signal wherein the transducer has conversion characteristics that determine how an amplitude of the ultrasonic pressure wave varies with an amplitude of the second ultrasonic signal across the first frequency range;
processing means for modifying the audio signal to compensate for the demodulating properties of the non-linear medium; and
a digital filter for modifying the audio signal to compensate for a variation, with frequency, of the conversion characteristics of the transducer across the first frequency range. - View Dependent Claims (14, 15, 16, 17, 18, 19, 20, 21)
- a transducer for converting the second ultrasonic signal into an ultrasonic pressure wave for transmission into a non-linear medium to allow demodulation of the ultrasonic pressure wave and thereby generate an audio pressure wave representative of the audio signal wherein the transducer has conversion characteristics that determine how an amplitude of the ultrasonic pressure wave varies with an amplitude of the second ultrasonic signal across the first frequency range;
Specification