Parametric array modulation and processing method
First Claim
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1. A system using the nonlinearity of a propagation medium to demodulate ultrasonic waves having an audio signal modulated onto the ultrasonic frequency, comprising:
- audio signal processing circuitry including;
delay means for the audio signal providing a delayed audio signal;
envelope generator means providing an envelope signal which is responsive to negative peaks of the audio signal over a predetermined interval; and
combiner means for the delayed audio signal and the envelope signal, the resulting combined signal being useful in processing for modulation of said ultrasonic frequency; and
premodulation processing means for processing the combined signal including the delayed audio signal and the envelope signal, thereby allowing the propagation medium demodulation to provide a demodulated acoustic signal which is a substantially accurate representation of the audio signal.
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Abstract
A system using the nonlinearity of a propagation medium to demodulate an ultrasonic wave having audio modulated onto the ultrasonic frequency, audio signal processing circuitry providing a delayed audio signal and an envelope signal which is a function of peaks of the audio signal over a predetermined interval. The delayed audio signal and the envelope signals are combined with the delay in the audio allowing the envelope signal to accurately be aligned with the audio signal in the combination.
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Citations
25 Claims
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1. A system using the nonlinearity of a propagation medium to demodulate ultrasonic waves having an audio signal modulated onto the ultrasonic frequency, comprising:
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audio signal processing circuitry including; delay means for the audio signal providing a delayed audio signal; envelope generator means providing an envelope signal which is responsive to negative peaks of the audio signal over a predetermined interval; and combiner means for the delayed audio signal and the envelope signal, the resulting combined signal being useful in processing for modulation of said ultrasonic frequency; and premodulation processing means for processing the combined signal including the delayed audio signal and the envelope signal, thereby allowing the propagation medium demodulation to provide a demodulated acoustic signal which is a substantially accurate representation of the audio signal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18)
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19. In a system using the nonlinearity of a propagation medium to demodulate ultrasonic waves having an audio signal modulated onto the ultrasonic frequency, audio signal processing circuitry comprising:
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envelope generator means for tracking negative peaks of the audio signal over a predetermined interval and inverting the negative peaks, thereby providing an envelope signal which is an approximate function of the inverted negative peaks of the audio signal over said predetermined interval, said approximate function having misalignment of the envelope signal and the audio signal; and means for converting the audio signal and the envelope signal into an ultrasonic signal characterized by a carrier signal and reduced misalignment. - View Dependent Claims (20, 21, 22)
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23. In a system using the nonlinearity of a propagation medium to demodulate ultrasonic waves having an original audio signal modulated onto the ultrasonic frequency, an audio signal processing method comprising the steps of:
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delaying the original audio signal to provide a delayed audio signal; generating an envelope signal which is responsive to negative peaks of the audio signal over a predetermined interval; combining the delayed audio signal and the envelope signal to produce a combined signal useful in processing for modulation of said ultrasonic frequency; and in a processing step, processing the combined signal including the delayed audio signal and the envelope signal, thereby allowing the propagation medium demodulation to provide a demodulated acoustic signal which is a substantially accurate representation of the original audio signal. - View Dependent Claims (24, 25)
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Specification