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Rolling code security system

  • US 8,194,856 B2
  • Filed: 07/22/2008
  • Issued: 06/05/2012
  • Est. Priority Date: 05/17/1995
  • Status: Expired due to Fees
First Claim
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1. A wireless transmitter for sending a radio frequency signal to a wireless receiver to actuate an electric motor to open or close a movable barrier, the wireless transmitter comprising:

  • an end-user switch;

    a radio frequency transmitter;

    a control circuit operably coupled to the end-user switch and to the radio frequency transmitter, the control circuit being configured to respond to an end-user assertion of the end-user switch by causing the radio frequency transmitter to transmit the radio frequency signal, at least in part, as a rolling code, wherein the rolling code is modulated onto a radio frequency carrier using both amplitude modulation and pulse-width modulation.

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