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Rolling code security system

  • US 7,492,905 B2
  • Filed: 08/14/2002
  • Issued: 02/17/2009
  • Est. Priority Date: 05/17/1995
  • Status: Expired due to Fees
First Claim
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1. In a barrier movement system comprising a receiver storing an expected code which responds to rolling codes transmitted by a transmitter, a method comprising:

  • a) receiving a transmitted first rolling code;

    b) operating the barrier movement system and updating the expected code when the received rolling code is within a predetermined range of the received rolling code;

    c) not operating the barrier movement system when the expected rolling code is not within the predetermined range of the received rolling code and not updating the expected code;

    d) receiving a subsequent rolling code after the performance of the not operating step and resynchronizing the receiver when the subsequent rolling code was transmitted by the same transmitter as the first rolling code;

    e) counting the number of times that step d) is performed and storing value representing the count;

    f) inhibiting the further performance of the resynchronizing of step d) when the stored number of performances of step d) exceeds a predetermined value.

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