Steering of directional sound beams
First Claim
1. Method for steering a directional audio beam that is self-demodulated from an ultrasound carrier, said method including the steps of:
- generating an audio signal;
generating an ultrasound carrier signal;
modulating said carrier signal with said audio signal;
adjusting both amplitude and phase of said audio signal and said carrier signal to steer said audio beam to a desired direction, wherein the amplitude and phase of said audio signal is adjusted in a first amplitude and phase adjustment module and the amplitude and phase of said carrier signal is adjusted in a second amplitude and phase adjustment module; and
combining outputs of said first and second amplitude and phase adjustment modules to generate an ultrasound beam driven in said direction by said modulated carrier signal.
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Accused Products
Abstract
Apparatus is disclosed for steering a directional audio beam that is self-demodulated from an ultrasound carrier. The apparatus includes means for modulating a carrier signal with an audio signal and means for adjusting the amplitude and phase of at least one of the audio signal and/or the carrier signal to steer the audio beam to a desired direction. The apparatus also includes means for generating an ultrasound beam in the desired direction driven by the modulated carrier signal. The apparatus may include means for weighting the audio and/or carrier signal by a zeroth order Bessel function to synthesize a Bessel distribution source. A corresponding method for steering a directional audio beam is also disclosed. A harmonic generator may be used to generate harmonics of low frequencies in the audio signal. The harmonics may provide (upon demodulation) a psycho-acoustic impression of improved perception of low frequencies. Further, a modulated ultrasonic signal or an unmodulated audio signal may be band-passed into two or more different band-limited signals. The band-limited signals may be amplified and transmitted by ultrasonic transducers having mechanical resonance frequencies substantially equal to a characteristic frequency of the band-limited signals. Ultrasonic processing of the audio signal may include square root methods without generating large numbers of harmonics.
51 Citations
11 Claims
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1. Method for steering a directional audio beam that is self-demodulated from an ultrasound carrier, said method including the steps of:
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generating an audio signal; generating an ultrasound carrier signal; modulating said carrier signal with said audio signal; adjusting both amplitude and phase of said audio signal and said carrier signal to steer said audio beam to a desired direction, wherein the amplitude and phase of said audio signal is adjusted in a first amplitude and phase adjustment module and the amplitude and phase of said carrier signal is adjusted in a second amplitude and phase adjustment module; and combining outputs of said first and second amplitude and phase adjustment modules to generate an ultrasound beam driven in said direction by said modulated carrier signal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 11)
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8. A method of processing an audio signal, including:
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performing a square root operation on the audio signal to generate a square rooted signal; alternating the gain of the square rooted signal between positive and negative gain values at selected locations to generate a flipped signal, wherein the selected locations of the signal are minimum turning points of the signal; modulating the flipped signal onto a first ultrasonic carrier wave; and offsetting the audio signal by a predetermined amount prior to performing square root operation to ensure that the square root operation only results in real values. - View Dependent Claims (9, 10)
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Specification