Acoustic wave communication apparatus and method
First Claim
1. A data modulation/demodulation method for an acoustic communication apparatus which receives an acoustic reception wave having reception data and a pseudo-noise sign, wherein said acoustic reception wave corresponds to an acoustic transmission wave having transmission data and a transmission pseudo noise sign, said method comprising the steps of:
- (a) receiving said acoustic reception wave;
(b) converting said acoustic reception wave into a digital reception wave;
(c) storing said digital reception wave as a stored reception wave;
(d) dividing said stored reception wave into a data portion and a pseudo-noise sign portion based on said pseudo-noise sign;
(e) determining at least one multipath delay characteristic value of said acoustic reception wave based on said pseudo-noise sign portion;
(f) determining a transmission waveform based on said data portion, wherein said transmission waveform contains an initial data waveform which precedes an initial delay wave;
(g) sequentially calculating delay waves relating to said transmission waveform based on said at least one multipath delay characteristic value; and
(h) respectively subtracting said delay waves from said transmission waveform in order to compensate for a delay distortion contained in said data portion to produce a delay distortion corrected waveform.
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Accused Products
Abstract
An apparatus for accurately transmitting and receiving acoustic waves indoors is provided. The apparatus contains a microphone, a speaker, a processing circuit, a first amplifier, a second amplifier, and a power control circuit. The microphone converts an input acoustic wave into an electric signal, and the speaker generates an output acoustic wave based on input data. The processing circuit processes the electric signal to produce processed data and outputs the input data to drive the speaker. The first amplifier receives a power signal and detects if a starting signal is contained in the electric signal output from the speaker. Then, the amplifier outputs a first detection signal when the starting signal is detected and outputs the power signal when the first detection signal is output. The second amplifier receives the power signal from the first amplifier and detects if a non-starting signal is contained in the electric signal when the starting signal is detected. The amplifier outputs a second detection signal when the non-starting signal is detected. The power control circuit supplies the power signal to the processing circuit when the first and second detection signals have a predetermined relationship. Furthermore, methods for accurately detecting data contained in the input acoustic wave are also provided.
19 Citations
18 Claims
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1. A data modulation/demodulation method for an acoustic communication apparatus which receives an acoustic reception wave having reception data and a pseudo-noise sign, wherein said acoustic reception wave corresponds to an acoustic transmission wave having transmission data and a transmission pseudo noise sign, said method comprising the steps of:
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(a) receiving said acoustic reception wave; (b) converting said acoustic reception wave into a digital reception wave; (c) storing said digital reception wave as a stored reception wave; (d) dividing said stored reception wave into a data portion and a pseudo-noise sign portion based on said pseudo-noise sign; (e) determining at least one multipath delay characteristic value of said acoustic reception wave based on said pseudo-noise sign portion; (f) determining a transmission waveform based on said data portion, wherein said transmission waveform contains an initial data waveform which precedes an initial delay wave; (g) sequentially calculating delay waves relating to said transmission waveform based on said at least one multipath delay characteristic value; and (h) respectively subtracting said delay waves from said transmission waveform in order to compensate for a delay distortion contained in said data portion to produce a delay distortion corrected waveform. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. A data modulation/demodulation method for an acoustic communication apparatus which receives an acoustic reception wave having reception data and a pseudo-noise sign, wherein said acoustic reception wave corresponds to an acoustic transmission wave having transmission data and a transmission pseudo noise sign, said method comprising the steps of:
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(a) receiving said acoustic reception wave; (b) converting said acoustic reception wave into a digital reception wave; (c) storing said digital reception wave as a stored reception wave; (d) dividing said stored reception wave into a data portion and a pseudo-noise sign portion based on said pseudo-noise sign; (e) determining at least one multipath delay characteristic value of said acoustic reception wave based on said pseudo-noise sign portion, wherein said at least one multipath delay characteristic values comprises a first delay time relating to a time delay between an initial time at which said data portion arrives and a subsequent time at which an initial delay wave begins; (f) evaluating a current sample of said data portion which arrives at a current sample time; (g) determining if said current sample time is less than said first delay time; (h) if said current sample time is less than said first delay time, designating said current sample of said data portion as a current portion of a delay corrected data portion; (i) if said current sample time is not less than said first delay time, calculating a current delay wave corresponding to said current sample time and subtracting said current delay wave from said current sample of said data portion to produce said current portion of said delay corrected data portion; (j) determining if said current sample of said data portion corresponds to a final sample of said data portion; and (k) if said current sample of said data portion does not correspond to said final sample, incrementing said current sample time by a predetermined value and repeating said steps (f) to (k). - View Dependent Claims (14, 15, 16, 17, 18)
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Specification