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Emergency alarm device

  • US 4,134,108 A
  • Filed: 01/21/1977
  • Issued: 01/09/1979
  • Est. Priority Date: 01/21/1977
  • Status: Expired due to Term
First Claim
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1. A transmitter-receiver emergency signalling device, the transmitter of which may be carried on the person, comprising:

  • (a) means for generating a system address pulse train of a fixed number of pulses, the width of each pulse being determined by whether or not the pulse represents a "one" or a "zero;

    "(b) means for setting the pulse width of the pulses in the pulse train and thereby determining the system address;

    (c) radio frequency transmission means the carrier signal of which is modulated by the pulse train;

    (d) a radio frequency receiver means responsive to the transmitted signal;

    (e) means for determing that each of the fixed number of pulses in the pulse train have been received;

    (f) address decoding means adapted to receive the pulse train and compare an address received with the system address; and

    (g) an alarm responsive to a comparison of the received address and the system address.

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