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Method and arrangement for digital transmission using am emitters

  • US 20030148743A1
  • Filed: 01/29/2003
  • Published: 08/07/2003
  • Est. Priority Date: 05/30/2001
  • Status: Active Grant
First Claim
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1. A method for digital transmission using AM transmitters in which, due to the non-linear operating mode during digital transmission, non-linear distortions arise which result in inband interference and the out-of-band and spurious emissions, wherein the output stage of the AM transmitter is operated in the linear mode;

  • the linear mode is operated in conjunction with a correction of the supply voltage of the transmitter output stage as a function of the instantaneous drive in order to improve the efficiency;

    the modulator of the AM transmitter operates as a switched-mode power supply unit and delivers the corrected supply voltage for the transmitter output stage;

    the envelope of the complex modulated data signal is scanned, and this signal controls the correction of the supply voltage for the transmitter output stage;

    the time constant during the scanning of the envelope is such that it is possible to immediately follow a rise in the envelope;

    the time constant during the scanning of the envelope can be equal for the rise and decay of the envelope; and

    the complex modulated data signal, subsequent to scanning its envelope, is delayed in such a manner that the correction of the supply voltage is effective in the meantime, thus preventing even short-duration overdrives of the transmitter output stage.

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