Electrical audio signal processing systems and devices – One-way audio signal program distribution
Reexamination Certificate
2006-12-05
2006-12-05
Chin, Vivian (Department: 2615)
Electrical audio signal processing systems and devices
One-way audio signal program distribution
C381S079000, C381S111000, C381S116000, C367S092000, C367S138000
Reexamination Certificate
active
07146011
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.
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Er Meng Hwa
Gan Woon Seng
Karnapi Furi Andi
Lee Chee Mun Kelvin
Liew Yew Hin
Chin Vivian
Faulk Devona E.
Nanyang Technological University
Rissman Jobse Hendricks & Oliverio LLP
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