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EMERGENCY WARNING AND IDENTIFICATION APPARATUS FOR TWO-WAY RADIO COMMUNICATION SYSTEM

  • US 3,581,208 A
  • Filed: 12/16/1968
  • Issued: 05/25/1971
  • Est. Priority Date: 12/16/1968
  • Status: Expired due to Term
First Claim
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1. Signal generating and processing apparatus usable in an audio communication system in which a plurality of signal generators each generate a signal having at least identifying and predetermined condition indicating components for transmission to a remote station signal and a second continuous wave frequency component of controllable duration, the received signal is processed to identify the originator of the signal and the respective condition of each originator, comprising:

  • signal generating apparatus associated with each originator, comprising;

    a. a manually adjustable switch having a first position for indicating a nonemergency transmit condition and a second position for indicating an emergency condition;

    b. means responsive to the positions of said switch for generating a first continuous wave frequency signal whose duration is substantially coextensive with the duration of a developed output signal;

    c. means responsive to the positions of said switch and to a developed gating signal for generating a second continuous wave frequency signal of controllable duration, said first and said second continuous wave frequencies comprising a unique combination for permitting identification of said signal generating apparatus at a remote station;

    d. gating circuitry means for developing said gating signal responsive to the positions of said switch for causing said second generating means to generate the second continuous wave frequency signal having a greater duration for said second switch position than for said first switch position so that emergency and nonemergency transmit conditions are distinguishable at the remote station, and e. means responsive to said first and second continuous wave frequency signals and a supplied third signal capable of having audio components, for mixing said three signals for generating an output signal for transmission to the remote station; and

    signal processing apparatus associated with a remote station, comprising;

    a. frequency separating means responsive to a unique combination of continuous wave frequency components in the signal received from an originator, including first and second filtering and detecting circuits for respectively separating said first and second continuous wave frequency components, and an AND circuit coupled to the first and second detecting circuits for developing a first signal for identifying said originator, said first signal additionally being representative of the duration of said continuous wave frequency components, and b. means responsive to said first signal for developing a second signal for indicating the duration of said controllable continuous wave frequency signal relative to a prescribed duration, the exceeding or nonexceeding of said prescribed duration corresponding to the existence of an emergency or nonemergency transmit condition, respectively, at the originator.

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