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Signalling system

  • US 7,796,676 B2
  • Filed: 10/21/2004
  • Issued: 09/14/2010
  • Est. Priority Date: 01/16/1997
  • Status: Expired due to Term
First Claim
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1. An acoustic data communication system comprising:

  • a first acoustic data communications device comprising;

    (i) an input terminal operable to receive electrical message data having a power spectrum which lies substantially over a first bandwidth, (ii) a spread spectrum encoder operable to spread the power spectrum of the message data substantially over a second bandwidth which is greater than the first bandwidth and which extends over a frequency band which is audible to humans; and

    (iii) an electroacoustic convertor operable to convert the data output by said spread spectrum encoder into corresponding acoustic signals having a bandwidth that extends over a frequency band audible to humans and for transmitting the acoustic signals into the atmosphere; and

    a second acoustic data communications device comprising;

    (i) an acoustoelectric converter operable to receive acoustic signals from the atmosphere and to convert the received acoustic signals into corresponding electrical signals;

    (ii) a spread spectrum decoder operable to despread the power spectrum of the received signals;

    (iii) a message regenerator operable to regenerate the message data transmitted by said first acoustic data communications device from the despread signals output by said spread spectrum decoder;

    (iv) a processor operable to process the regenerated message data and operable to output a control signal in dependence upon the regenerated message data and (v) an output coupled to the processor and operable to receive the control signal and to output a human discernable response in dependence upon the control signal.

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