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Parametric array modulation and processing method

  • US 7,596,228 B2
  • Filed: 08/26/2003
  • Issued: 09/29/2009
  • Est. Priority Date: 08/26/2002
  • Status: Active Grant
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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