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Self adjusting antenna impedance for credential detection in an access control system

  • US 10,243,254 B2
  • Filed: 08/25/2016
  • Issued: 03/26/2019
  • Est. Priority Date: 08/25/2016
  • Status: Active Grant
First Claim
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1. A method of detecting the presence of a credential with a credential reader, the credential reader including an antenna circuit having an antenna to transmit and to receive a signal, the method comprising:

  • transmitting an energizing signal with the antenna;

    receiving a modified energizing signal with the antenna;

    demodulating the received modified energizing signal to determine an I value and a Q value of the received modified energizing signal; and

    adjusting a component of the antenna circuit as a function of one of the I value and the Q value.

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