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Locating a backscatter-based transponder

  • US 9,661,401 B2
  • Filed: 02/03/2014
  • Issued: 05/23/2017
  • Est. Priority Date: 12/13/2004
  • Status: Active Grant
First Claim
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1. A method comprising:

  • receiving, by a transponder, a locating command for locating the transponder;

    in response to receiving the locating command, transmitting, by the transponder, in a persistent operating state, a locating signal for locating the transponder;

    comparing, by an impedance control device coupled to a memory and a counter, a counter state of the counter with a counter value stored in the memory;

    in response to determining that the counter state matches the stored counter value, changing, by the impedance control device, a state of a modulation signal, such that a phase of the locating signal is changed;

    in the persistent operating state, receiving, by the transponder, a switch-off command while simultaneously transmitting, without an interruption for receiving the switch-off command, the locating signal; and

    discontinuing transmission of the locating signal in response to one or more of;

    receiving the switch-off command; and

    an expiration of a pre-determined period of time.

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