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Clear channel selection system for a cordless telephone

  • US 6,041,240 A
  • Filed: 03/10/1997
  • Issued: 03/21/2000
  • Est. Priority Date: 01/05/1994
  • Status: Expired due to Term
First Claim
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1. A cordless telephone set exhibiting an off-hook state for enabling communication via an external telephone network, and an on-hook state, said cordless telephone set comprising:

  • a base unit operating on one of a plurality of cordless telephone channels;

    a handset operating on said one of said plurality of cordless telephone channels;

    each of said cordless telephone channels including a first radio frequency for communication from said handset to said base unit and a second radio frequency for communication from said base unit to said handset;

    said base unit including an input for receiving a signal from said handset at said first radio frequency of a first cordless telephone channel;

    said handset including an input for receiving a signal from said base unit at said second radio frequency of said first cordless telephone channel;

    said base unit including a microprocessor for controlling said base unit, a portion of said microprocessor functioning as a signal detector circuit responsive, during said on-hook state, to a baseband signal derived from said first radio frequency signal for producing a first output signal indicative of said first channel being occupied, or indicative of a noise signal being present on said first channel;

    said handset including a microprocessor for controlling said handset, a portion of said microprocessor functioning as a signal detector circuit responsive, during said on-hook state, to a baseband signal derived from said second radio frequency signal for producing a second output signal indicative of said first channel being occupied, or indicative of a noise signal being present on said first channel;

    said signal detector circuit of said base unit and said signal detector circuit of said handset each having a threshold of detection of a first value in said on-hook state and of a second value, higher than said first value, in said off-hook state;

    said signal detector of said base unit and said signal detector of said handset operating in said off-hook mode for detecting baseband digital control signals;

    said microcomputer in said handset causes a transmission of a channel change command to said base unit and causes said handset to change to the same new channel in response to said second output signal.

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