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Radio identification systems

  • US 4,180,815 A
  • Filed: 01/20/1978
  • Issued: 12/25/1979
  • Est. Priority Date: 01/24/1977
  • Status: Expired due to Term
First Claim
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1. A transponder for use in a radio identification system comprising:

  • a receiver for receiving interrogating signals transmitted from an interrogating station;

    processing means for processing the received interrogating signals to produce reply signals in response thereto;

    a transmitter for transmitting said reply signals;

    storage means for temporarily storing a new interrogating signal received while the processing means is occupied in processing a previously received interrogating signal, at least until the processing means is capable of independently processing the new interrogating signal; and

    variable delay means arranged to delay the transmission of the reply signal to each received interrogating signal by an amount inversely dependent upon the length of any delay introduced by storage of the interrogating signal in the said storage means, so that the overall delay between the reception of an interrogating signal and the transmission of a reply signal thereto is substantially constant for any interrogating signal.

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