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System and method for detection of aural signals

  • US 5,495,242 A
  • Filed: 08/16/1993
  • Issued: 02/27/1996
  • Est. Priority Date: 08/16/1993
  • Status: Expired due to Fees
First Claim
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1. A warning system responsive to an audio signal for providing a warning signal comprising:

  • means for receiving an audio frequency signal, the audio frequency signal being in one of a band of frequencies, and the receiving means also simultaneously receiving other audio frequency signals;

    signal processing means for processing all of the received audio frequency signals, said processing means including means for converting the received audio frequency signals to digital signals, sampling the digital signals at a predetermined sample rate, scaling the resulting samples as a function of an average signal energy value, transforming the scaled samples into a transform coveting a range of audio frequencies within the band of frequencies and means for correlating the resulting, transform to determine if a received audio frequency signal represents an audio signal to which the system should respond;

    comparing means for comparing the autocorrelation with a set of criteria representing an audio frequency signal to which the system should respond to determine if such an audio frequency signal has been received; and

    ,means for generating said warning signal in response to the audio frequency signal being received, the signal processing means generating the warning signal when the correlation means indicates a received audio frequency signal corresponds with the audio signal to which the system should respond.

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