Vehicle security system based on two step communication range between transmitter and receiver

  • US 5,602,535 A
  • Filed: 07/15/1994
  • Issued: 02/11/1997
  • Est. Priority Date: 07/15/1994
  • Status: Expired due to Term
First Claim
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1. A method of selectively controlling a vehicle alarm system comprising a transmitter and a security module responsive to a control code from said transmitter, the method comprising the steps of:

  • adjusting a variable feature of said transmitter to define a first predetermined distante;

    from a transmitter having a sufficient power source, transmitting a first control code within said first predetermined distance with said transmitter;

    after said transmitting step, responding to said first control code with said security module only if said security module is within said first predetermined distance of said transmitter, wherein said first predetermined distance is a first short distance;

    adjusting a variable feature of said transmitter to define a second predetermined distance;

    programming said security module to respond to a second control code and not to respond to said first control code;

    transmitting said second control code within said second predetermined distance with said transmitter; and

    responding to said second control code from said transmitter with said security module only if said security module is within said second predetermined distance of said second transmitter, wherein said second predetermined distance is a second distance which exceeds said first short distance.

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