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ANAN-100 Predistortion tests

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  • abhiarunoday16
    Hello Group, Thanks to Warren, NR0V I have had the privilege to be a part of the test group testing Warren s Predistortion code, this version of PSDR replaces
    Message 1 of 35 , Dec 21, 2013
    Hello Group,

    Thanks to Warren, NR0V I have had the privilege to be a part of the test group testing Warren's Predistortion code, this version of PSDR replaces DttSP with Warren's UDSP engine,

    The firmware to support the code has been written by Phil, VK6APH and Doug, W5WC has been instrumental in embedding the new DSP engine,

    My congratulations to the Software Gurus, this is a huge step forward and I am honored and privileged to be associated with such a talented group of people,

    Attached is a very brief test report, I intend to do a little more comprehensive testing over the next few days,

    73s,
    Abhi
  • Karel Fassotte
    Thanks, Helmut This is the way I am thinking about on how to implement QAM, COFDM in DRM but on shortwave, thats the only difference. As in COFDM, QAM
    Message 35 of 35 , Dec 25, 2013
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      Thanks, Helmut
      This is the way I am thinking about on how to implement QAM, COFDM in DRM but on shortwave, thats the only difference.

      As in COFDM, QAM modulation, I understand that the individual amplitude levels of all carriers produce their own IM products, patterns, in the amplifier train. The magnitude of these IM products will depend on the linearity response of the amplifiers amplitude, frequency and phase. Right?

      My question: If you have N bits constellations. You send a trainings session, containing these constallations and patterns. Record the samples at the output of the antenna. Compare these output samples with the original input samples? Calculate for each carrier its distortion, calculate the predistortion to cancel out the distortion at the end of the line. This feedback can be picked up with a loop, and an inserted in-line variable attenuator to ashures to correct the amplitude level of the RX antenna input.

      The other cross correlated distortion patterns of higher order we just leave, These should be sufficiently down to worry about.
      Greetings.
      Karel
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