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837Re: Decoding Speed

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  • qrq_cw
    Dec 31 6:57 AM
      "KC8UDX" <KC8UDX@n...> wrote:


      > Tried different adjustments on Kenwood with just
      > minor changes to sig/noise ratio.

      A kenwood 520 is going to have a fixed (probably 2.8kHz) SSB filter.
      Look at your waterfall display- do you notice that it's noticeably
      dimmer towards the right side? This might indicate you've got too
      much rolloff on the high end. If all the "bars" look reasonably
      equally bright then bandwidth probably isn't a problem. With a 520
      there aren't a lot of adjustments you can make, except playing with
      RF gain and AF volume. Just make sure you're not overdriving the
      input to the soundcard.

      > Any filter programs out there that might help
      > cleanup the signal?

      I would recommend as little filtering or processing of the signal as
      possible. This modulation scheme is sensitive to phase and amplitude
      distortion and filtering can only make it worse. I run my bandwidth
      filters wide open and have had the best success with that. Attempts
      to use filters to cut down on adjacent channel interference or using
      the automatic notch to wipe out the perpetual "tuner-uppers" only
      results in bad blocks or no decode anyway. Give the decode engine
      the whole signal and let the error correction deal with any

      My $.02

      Mark K5LXP
      Albuqueruqe, NM
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