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Method and apparatus for powering and signaling over a single wire pair

  • US 5,517,172 A
  • Filed: 09/19/1994
  • Issued: 05/14/1996
  • Est. Priority Date: 09/19/1994
  • Status: Expired due to Fees
First Claim
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1. A remote access granting system comprising:

  • a remote access requester having a first input for receiving a user-supplied identification code including code data having first and second logic states, having a second input for receiving a first access granted signal, having first and second outputs for providing corresponding first and second access request signals in response to a code datum being in the first and second logic states, respectively, and having a third output for providing an access accepted signal in response to the first access granted signal;

    a remote access interface having first and second inputs coupled to the first and second outputs, respectively, of the remote access requester for receiving the corresponding first and second access request signals, having an output for providing the first access granted signal in response to a second access granted signal, and having a bi-directional terminal for receiving a DC voltage signal, for receiving the second access granted signal, for modulating the DC voltage signal with a first modulating signal having a first pulsewidth in response to the first access request signal and for modulating the DC voltage signal with a second modulating signal having a second pulsewidth in response to the second access request signal;

    a controller interface having an input for receiving a third access granted signal, having a bi-directional terminal coupled to the bi-directional terminal of the remote access interface for receiving the first and second modulated signals, for providing the DC voltage signal, and for modulating the DC voltage signal with the second access granted signal in response to the third access granted signal, having a first output for supplying a third access request signal in response to the first modulating signal, and having a second output for supplying a fourth access request signal in response to the second modulating signal; and

    a controller having first and second inputs coupled to the first and second outputs, respectively, of the controller interface for receiving the third and fourth access request signals, respectively, and having an output coupled to the input of the controller interface for providing the third access granted signal in response to the third and fourth access request signals matching a predetermined code data sequence.

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