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Wireless monitoring system and child station therefor

  • US 20070298716A1
  • Filed: 03/29/2007
  • Published: 12/27/2007
  • Est. Priority Date: 03/31/2006
  • Status: Active Grant
First Claim
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1. A wireless monitoring system using a base station and a child station, comprising:

  • said base station including;

    a base-station transmitting antenna for transmitting an electric power supplying carrier and a signal transmitting carrier to said child station; and

    a base-station receiving antenna for receiving an output from said child station;

    said child station including;

    a child-station receiving antenna which comprises a balanced antenna;

    a nonlinear circuit that receives an output from said child-station receiving antenna;

    a smoothing circuit that receives an output from said nonlinear circuit;

    a first high-frequency band-pass filter, a pass band of said first high-frequency band-pass filter comprising a frequency of said electric power supplying carrier;

    an intermediate-frequency band-pass filter, a pass band of said intermediate-frequency band-pass filter comprising an intermediate frequency which comprises a differential frequency between said electric power supplying carrier and said signal transmitting carrier;

    a demodulator that receives an output from said intermediate-frequency band-pass filter and uses an output from said smoothing circuit as a power source, a baseband circuit that modifies a baseband signal using an output from said demodulator;

    a modulator for modulating a high frequency signal outputted from said first high-frequency band-pass filter by using said baseband signal; and

    a child-station transmitting antenna for radiating an output from said modulator, wherein said base-station transmitting antenna and said child-station receiving antenna comprise circularly-polarized antennas which have a same rotating direction, and said child-station transmitting antenna and said base-station receiving antenna comprise circularly-polarized antennas which have a polarization characteristic rotating in a direction opposite to said base-station transmitting antenna and said child-station receiving antenna.

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