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Public alert and advisory systems

  • US 4,415,771 A
  • Filed: 04/03/1981
  • Issued: 11/15/1983
  • Est. Priority Date: 04/03/1981
  • Status: Expired due to Fees
First Claim
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1. A public alert and advisory system comprising:

  • a central transmitter station including first transmitter modulation means for modulating a signal to be transmitted with programming, using double sideband amplitude modulation, for transmission of the programming to manually controllable first receivers having first receiver demodulation means responsive to double sideband amplitude modulated signals for the reception and demodulation of said modulated signal to allow selective perception of the programming by members of the public,second modulation means coupled to said central transmitter station for modulation of the signal to be transmitted with public alert and advisory information utilizing narrow band small angle quadrature modulation of the carrier of the amplitude modulated signal, to which said first receiver demodulation means are not primarily responsive,alert and advisory signal means coupled to said second modulation means for providing a signal responsive to alert and advisory information thereto which is at least partially a voice signal,a plurality of remote second receivers, each of said second receivers having second receiver demodulation means responsive to said narrow band small angle quadrature modulation for the reception and demodulation of the transmitted signal to provide the public alert and advisory information at the respective remote location, said second receivers each also including presentation means for presenting said alert and advisory information in humanly perceivable form at the respective remote location, said second receiver each further including self initiating means coupled to said second receiver demodulation means for presenting a humanly perceivable malfunction signal at the respective remote location if said self initiating means is not periodically reset by a reset signal received from said second receiver demodulation means, andmeans coupled to said second modulation means of said central transmitter to provide a periodic signal thereto for transmission to and demodulation by said remote second receivers to periodically provide said reset signal thereto, whereby said humanly perceivable malfunction signal will be presented at the remote location of any said second remote receiver not receiving and responsive to said reset signal.

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