Directional Microphone
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Accused Products
Abstract
A directional microphone system includes an ultrasonic emitter and receiver. The emitter directs a beam of ultrasound at the audio source with sufficient intensity that non-linear air effects cause non-linear interactions between the ultrasonic sound and the source'"'"'s sonic sound. Ultrasonic frequency-mired sounds are thereby generated and these are received by the ultrasonic receiver. Signal-processing is carried out on the received signals to strip out the audio signals. The emitter and receiver may be co-located and the emitted beam may be focussed at the location of the audio source. The receiver may also be directional acid focussable. The directional microphone system may be very small and yet highly directional at sonic including low audible frequencies.
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Citations
63 Claims
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1-32. -32. (canceled)
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33. Directional microphone system for monitoring a source of acoustic signals in a low frequency range, the system comprising:
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one or more directional emitters of an acoustic ultrasonic frequency signal; one or more receivers for receiving acoustic signals in the ultrasonic frequency range, including signals at frequencies shifted by a frequency shift representing signals in the low frequency range as emitted by the source; and a signal processor to extract the signals in the low frequency range from the received signal. - View Dependent Claims (34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 61, 62)
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55. A method of receiving an acoustic source signal, said method comprising the steps of:
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(a) generating an ultrasonic acoustic signal in a directional beam of sufficient intensity to cause non-linear frequency mixing between said source signal and said ultrasonic acoustic signal; (b) receiving the signal caused by the non-linear frequency mixing; and (c) extracting the source signal from the received signal. - View Dependent Claims (56, 57, 58, 59, 60, 63)
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Specification