Modulator-amplifier
First Claim
Patent Images
1. A modulator/amplifier (ModAmp) comprising:
- a carrier reference generator for generating a carrier signal;
an event generator configured for comparing an audio input signal to the carrier signal, and generating event trigger signals based on said comparing;
an AM modulator configured for receiving the event trigger signals and generating double sideband modulation of the carrier signal;
an SSB modulator configured for receiving the event trigger signals and generating SSB modulation of the carrier signal; and
an output driver configured for receiving AM modulated or SSB modulated carrier signals and outputting a drive signal based thereon suitable for driving an ultrasonic transducer in a parametric sound reproduction system;
wherein event trigger signals are related to the audio input signal by a non-linear function and modulation is switch-mode modulation based on the event trigger signals.
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Abstract
A method and device for frequency shifting and amplifying an audio signal for use in a parametric loudspeaker system is disclosed. The method includes the operation of receiving an input audio signal and creating a reference signal. The audio signal is compared with the reference signal to derive a compared product signal. The compared product signal is sent to a switching power stage. Nonlinear preprocessing is performed with respect to the input audio signal, and/or a non-triangle wave is created as the reference signal. The input audio signal is shifted and amplified by modulating the reference signal in the switching power stage.
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Citations
20 Claims
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1. A modulator/amplifier (ModAmp) comprising:
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a carrier reference generator for generating a carrier signal; an event generator configured for comparing an audio input signal to the carrier signal, and generating event trigger signals based on said comparing; an AM modulator configured for receiving the event trigger signals and generating double sideband modulation of the carrier signal; an SSB modulator configured for receiving the event trigger signals and generating SSB modulation of the carrier signal; and an output driver configured for receiving AM modulated or SSB modulated carrier signals and outputting a drive signal based thereon suitable for driving an ultrasonic transducer in a parametric sound reproduction system; wherein event trigger signals are related to the audio input signal by a non-linear function and modulation is switch-mode modulation based on the event trigger signals. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A method for frequency shifting and amplifying an audio signal for use in a parametric loudspeaker system, including the steps of,
i) receiving at least one input audio signal, ii) creating at least one reference signal, iii) comparing the at least one input audio signal with the at least one reference signal to derive at least one compared product signal, iv) delivering the at least one compared product signal to a switching power stage wherein at least one operation is performed selected from the following: -
a) performing nonlinear preprocessing with respect to the input audio signal, and, b) creating a non-triangle wave as the at least one reference signal; and v) frequency shifting and amplifying the input audio signal by modulating the reference signal in the switching power stage. - View Dependent Claims (11, 12, 13, 14, 15, 16, 17)
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18. A modulator-amplifier operable for use in a parametric sound reproduction system for reproducing audio information in a medium, comprising:
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an input configured for receiving at least one input signal including audio information; at least one reference signal generator configured for generating at least one carrier signal; a switch mode modulator configured to modulate the at least one carrier signal, configured so that there is a non-linear relationship between the at least one input signal and state transitions of a switching output waveform; and wherein the modulator-amplifier is configured to generate an output signal that has been shifted in frequency relative to a frequency of the at least one input signal and wherein the output signal includes at least one sideband. - View Dependent Claims (19)
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20. A system for generating an acoustic output reproducing an audio signal in an acoustic parametric array in an acoustic wave-transmitting medium, comprising:
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a) a modulator-amplifier which produces a modulated carrier wave output which comprises a carrier waveform at an ultrasonic frequency modulated so as to include a processed audio signal, the modulated carrier wave output is operable for driving a transducer to reproduce the audio signal from the acoustic parametric array; the modulator-amplifier including an event generator for generating a timing signal based on comparison of the audio signal and a carrier signal; the modulator-amplifier further comprising a switching output stage coupled to the event generator for signaling the switching output stage, wherein timing of switching state transitions in the switching output stage is related to the audio signal by a non-linear function; and b) an ultrasonic transducer coupled to the modulator-amplifier which converts the modulated carrier wave output into an ultrasonic waveform for producing an audio wave in a medium, whereby a pre-processed audio source signal is amplified and reproduced from the parametric array in the medium.
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Specification