Modulator processing for a parametric speaker system
First Claim
1. A signal processor for a parametric loudspeaker system, comprising:
- at least one carrier frequency generator to produce a carrier frequency;
a modulator which receives at least one audio signal and modulates the at least one audio signal onto the carrier frequency to produce a modulated signal, wherein the at least one audio signal is converted to sideband frequencies which are divergent from the carrier frequency by the frequency value of the at least one audio signal;
an error correction compensator coupled to the modulator to compensate for inherent parametric demodulation distortion by modifying, substantially within the modulated signal'"'"'s bandwidth, the modulated signal to approximate the ideal audio signal which should be output by the system.
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Accused Products
Abstract
A parametric loudspeaker system using improved modulators to compensate for the non-linearity of the parametric process in air when driving the air at saturation levels and below saturation levels. The parametric loudspeaker uses a pre-processed single sideband modulator that offers ideal linearity as characterized by square root pre-processed double sideband modulators but with a lower carrier frequency and without the wide bandwidth requirements. By eliminating some or all of the lower sideband the carrier frequency can be reduced without producing sideband frequencies in the audible range. Lower operational frequencies result in greater translation efficiency and greater output capability before reaching the saturation limit of air. A pre-processor minimizes the effects of saturation limits for double sideband, truncated double sideband or single sideband processing to achieve superior output.
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Citations
18 Claims
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1. A signal processor for a parametric loudspeaker system, comprising:
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at least one carrier frequency generator to produce a carrier frequency; a modulator which receives at least one audio signal and modulates the at least one audio signal onto the carrier frequency to produce a modulated signal, wherein the at least one audio signal is converted to sideband frequencies which are divergent from the carrier frequency by the frequency value of the at least one audio signal; an error correction compensator coupled to the modulator to compensate for inherent parametric demodulation distortion by modifying, substantially within the modulated signal'"'"'s bandwidth, the modulated signal to approximate the ideal audio signal which should be output by the system. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17)
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18. A signal processor for a parametric loudspeaker system, comprising:
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at least one carrier frequency generator to produce a carrier frequency, wherein the carrier frequency is included in a single sideband (SSB) signal that includes a distortion compensator to correct for parametric demodulation distortion; a modulator for (i) receiving audio signals within an audible range and modulating the audio signals onto the carrier frequency to produce a modulated signal, and (ii) for reducing the carrier frequency of the modulated signal to a value close to an upper limit of the audible range, wherein the audio signals are converted to sideband frequencies which are divergent from the carrier frequency by the frequency value of the audio signal;
whereinthe distortion compensator uses an ideal audio signal created by applying a square root function to the ideal audio signal, wherein the ideal signal is used as a reference to modify the modulated signal and correct for an inherent parametric demodulation distortion.
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Specification