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Re: BPSK31 or MT63

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  • zl1bpu
    Bob, I would expect PSK31 to be more sensitive under weak signal conditions that MT63. These things are very deceptive. You get the impression that MT63 is
    Message 1 of 4 , Dec 10, 2007
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      Bob,

      I would expect PSK31 to be more sensitive under weak signal conditions
      that MT63.

      These things are very deceptive. You get the impression that MT63 is
      more sensitive because you can still copy when you can't hear the
      signal, but that's because the signal largely sounds like noise. It is
      fairly easy to prove which mode is more sensitive using an ionospheric
      simulator such as Moe AE4JY's 'Pathsim' program. Just add noise to see
      what happens.

      While we're about it, I'll answer the unasked question about other
      conditions as well. Once again, you can prove it with a simulator, but
      PSK31 does best with direct or single hop paths, and performs badly
      with polar paths and those with lots of spread F (scatter). MT63 copes
      with scatter better, but is even worse on polar paths because the
      lower baud rate is more affected by Doppler. Neither are terribly good
      on 80m, where multi-path and strong QRM are the order of the day.

      I'd recommend using DominoEX for most of these conditions. It is as
      sensitive as PSK31, does not suffer from Doppler or scatter problems,
      and eats 80m multipath for breakfast. You have to choose the speed
      with care - 11 baud is OK on 20m, but on 80m, use 8 baud, especially
      early evening. For very, very weak sigs, say LF, 6m or 2m DX, use 4
      baud - it works at -18dB S/N and still goes at 25 WPM!

      73,
      Murray ZL1BPU
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