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Transmitter-receiver coded security alarm system

  • US 4,631,527 A
  • Filed: 11/25/1980
  • Issued: 12/23/1986
  • Est. Priority Date: 11/25/1980
  • Status: Expired due to Term
First Claim
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1. A transmitter-receiver burglar alarm system comprisinga battery powered transmitter unit including a transmitter of radio waves,means for sensing a low battery voltage at said transmitter unit,said transmitter unit having means for transmitting a low battery voltage signal, and means for transmitting a channel selecting code bit,means connected to the transmitter unit for preventing said transmitter unit from making further transmissions after transmitting said low battery voltage signal,a base station including a receiver for receiving radio waves transmitted by said transmitter unit,said base station having means responsive to transmission of said channel selecting code bit to provide a first audible sound and responsive to the absence of said channel selecting code bit to produce a second audible sound,said base station further including at will actuatable means responsive to receipt of said channel selecting code bit for producing a third audible sound, andmeans responsive to said low battery voltage signal for producing a fourth audible sound.

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