Trainable transceiver capable of learning variable codes

  • US 5,661,804 A
  • Filed: 06/27/1995
  • Issued: 08/26/1997
  • Est. Priority Date: 06/27/1995
  • Status: Expired due to Term
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First Claim
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1. A trainable transceiver for installation in a vehicle for receiving an activation signal that includes a variable code and learning characteristics of the activation signal for subsequently transmitting a signal having the same characteristics for remotely actuating a device, said trainable transceiver comprising:

  • a receiver for receiving an activation signal from a remote transmitter used to remotely actuate a device;

    a controller coupled to said receiver and operable in a learning and an operating mode, said controller receiving the activation signal in said learning mode, recognizing the presence of a variable code, identifying one of a plurality of prestored cryptographic algorithms related to the cryptographic algorithm used by the remote transmitter to generate the rolling code, and storing data identifying the cryptographic algorithm and last transmitted code of the activation signal; and

    in said operating mode, said controller generates output data representing a next sequential code of the variable code using the identified cryptographic algorithm and the data represented the last transmitted code; and

    a signal generator coupled to said controller for receiving said output data from said controller and for transmitting a modulated signal, which corresponds to the received activation signal and includes a variable code recognizable by a receiver of the remote device for actuation thereof.

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