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Linear-modulation type radio transmitter

  • US 5,113,525 A
  • Filed: 10/19/1990
  • Issued: 05/12/1992
  • Est. Priority Date: 11/06/1989
  • Status: Expired due to Fees
First Claim
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1. A linear-modulation type radio transmitter, comprising:

  • a linear modulator for producing a carrier wave linearly modulated based on a modulation signal;

    a transmission power amplifier capable of adjusting its transmission gain and for amplifying said linearly-modulated carrier wave;

    a transmit antenna for radiating, as an electromagnetic radio wave, an amplified signal output from said transmission power amplifier into space;

    a monitor wave generator for generating a monitor wave at a predetermined amplitude having frequencies other than those within the transmission band of said carrier wave, and means of combining said monitor wave together with said linearly-modulated carrier wave and for inputting the combined monitor wave and linearly-modulated wave to said transmission power amplifier;

    a level detector for detecting the level of components of said monitor wave out of output signal waves from said transmission power amplifier and for converting the same into a detection voltage corresponding to the level of the components of said monitor wave; and

    an error amplifier for producing a control signal for adjusting the gain of said transmission power amplifier based on the detection voltage from said level detector.

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