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SILENT EMERGENCY ALARM SYSTEM FOR SCHOOLS AND THE LIKE

  • US 3,750,131 A
  • Filed: 08/06/1971
  • Issued: 07/31/1973
  • Est. Priority Date: 08/06/1971
  • Status: Expired due to Term
First Claim
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1. In a stationary structure defining a plurality of discrete stationary locations and a central stationary location, a method of indicating at said central location the existence of an emergency in any of said discrete locations, the method including the steps of:

  • providing in each of said discrete stationary locations fixedly located detection means for detecting a supersonic signal generated therein;

    providing in said central location display means, which are directly connected by means of continuous wires to the detection means in the various discrete locations, and which include a plurality of indicators, each associated with a different detection means and energized when the detection means with which it is associated detects a supersonic signal;

    generating in each discrete stationary location at which an emergency exists a supersonic signal which is detected by the detection means in the discrete location;

    providing audio means in at least one of said discrete stationary locations, said audio means including a variabe gain audio amplifier; and

    automatically increasing the gain of said amplifier when the detection means in the stationary location detect a supersonic signal which is generated therein.

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