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Time code telephone security access system

  • US 4,761,808 A
  • Filed: 03/18/1987
  • Issued: 08/02/1988
  • Est. Priority Date: 03/18/1987
  • Status: Expired due to Fees
First Claim
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1. A security access control system for controlling access of users to an information processing system, said security access control system comprising:

  • a plurality of remote terminals each comprising a signal generating means for generating a coded identification signal and a transmitting means for transmitting said coded identification signal;

    a base terminal comprising a receiving means for receiving said coded identification signals, a signal processing means for decoding and determining the validity of each of said coded identification signal, and an access control means for controlling access to said information processing system;

    each of said coded identification signals generated by said signal generating means of said remote terminal comprising a sequence of a predetermined number of alphanumeric digits, a first group of said alphanumeric digits comprising a time code and a second group of said alphanumeric digits comprising an address code;

    said time code changing periodically in a predetermined manner;

    said address code remaining essentially constant over time;

    each of said signal generating means comprising a first time code memory means containing a first predetermined sequence of time codes, and a first clock means for selecting a first time code from said first sequence of time codes contained in said first time code memory means;

    said signal processing means of said base terminal comprising a second time code memory means containing a second predetermined sequence of time codes and a second clock means; and

    said signal processing means further comprising first comparator means for comparing said time code component of said incoming identification signal with a second time code selected according to the time indicated by said second clock means from said second time code memory means;

    whereby said base terminal denies access to said information processing system if said time code component of said incoming identification signal and said second time code are not identical.

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