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Multi-frequency communication system with an improved diversity scheme

  • US 5,369,800 A
  • Filed: 05/20/1992
  • Issued: 11/29/1994
  • Est. Priority Date: 08/16/1991
  • Status: Expired due to Fees
First Claim
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1. A multi-frequency communication system comprising:

  • a transmitting section including;

    modulation means including an oscillator for generating a first carrier and a mixer, for modulating the first carrier with data to be transmitted, thereby to generate a modulated output;

    first local oscillation means for generating a first local oscillating signal which is to be used as a second carrier;

    first mixer means for mixing the modulated output from said modulation means and the first local oscillating signal generated by said first local oscillation means, thereby to generate waves of different frequencies, including at least an upper side band wave having a frequency which is a sum of the frequencies of the modulated output and the first local oscillating signal and a lower side band wave having a frequency which is a difference between the frequencies of the modulated output and the first local oscillating signal; and

    transmitting antenna means for radiating electromagnetic waves into the air, the electromagnetic waves including the waves of different frequencies generated by said first mixer means; and

    a receiving section including;

    receiving antenna means for receiving the electromagnetic waves including the waves of different frequencies and radiated from said transmitting antenna means;

    diversity means for extracting at least one wave of the upper side band wave and the lower side band wave from the waves of different frequencies received by said receiving antenna means;

    second local oscillation means for generating a second local oscillating signal equal to the first local oscillating signal;

    second mixer means for mixing the at least one wave extracted by said diversity means and the second local oscillating signal generated by said second local oscillation means, thereby to generate an output; and

    demodulation means for demodulating the output generated by said second mixer means, thereby to recover the data to be transmitted by the transmitting section.

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