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Encoder and decoder microchips and remote control devices for secure unidirectional communication

  • US 6,175,312 B1
  • Filed: 12/04/1992
  • Issued: 01/16/2001
  • Est. Priority Date: 05/29/1990
  • Status: Expired due to Term
First Claim
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1. A system comprising an encoder microchip and a decoder microchip, wherein the encoder microchip comprises:

  • a circuit in which a first identification number is stored, a circuit in which a counter value is stored, a first logic circuit to change the value of the counter value only when the encoder microchip is operated, and a non-linear encoding circuit to encode the counter value using the first identification number to generate a transmission value decodable to provide the counter value;

    wherein the decoder microchip comprises;

    a circuit in which a second identification number is stored;

    a circuit in which the transmission value from the encoder microchip is received;

    a circuit in which the transmission value is decoded using the second identification number to generate from the transmission value a decoded counter value;

    a circuit in which a second decoded counter value obtained from a transmission value of a previous transmission is stored; and

    a circuit in which signals are scanned to identify signals conforming to a specific format.

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