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Re: [Fwd: Re: [linuxham] S/N numbers for Olivia]

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  • Brian Lloyd
    Perhaps some would like to know how I compared DM780 s and fldigi s performance when copying olivia. First, my setup: Flex 5000 A transceiver Generic PC with
    Message 1 of 4 , Dec 1, 2008
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      Perhaps some would like to know how I compared DM780's and fldigi's
      performance when copying olivia.

      First, my setup:

      Flex 5000 A transceiver
      Generic PC with AMD64 duo-core processor running WinXP home, PowerSDR
      1.14.0, DM780, and fldigi 3.30
      line out from the F5K to the line-in on my MacBook Pro

      I started out by running fldigi on both the MacBook pro and on the PC
      on the same signal. Fldigi was connected to PowerSDR via VAC on the
      PC. Fldigi on the Mac was getting the analog signal. Over time I
      monitored both copies of fldigi receiving the same signals in varying
      conditions. From what I could tell by eyeball looking at the S/N
      display and at the actual copy, the performance of fldigi on both
      platforms was virtually identical. S/N numbers never varied by more
      than a couple tenths of a dB (as fast as I could look from one to the
      other). The copy was also virtually identical. From this I deduced
      that the two computing platforms were performing virtually identically.

      After that I stopped fldigi on the PC platform and started DM780.
      Since the S/N report from DM780 does not appear to be the same as for
      fldigi I could not compare. All I could do is compare the copy from
      DM780 and from fldigi. This comparison was more difficult but one
      thing was clear, fldigi would continue to copy correctly at lower
      signal levels than DM780. Copy would become garbled from DM780 before
      it would from fldigi. Trying to estimate signal level change on
      signals experience slow QSB and comparing that to copy quality let me
      to believe that fldigi is giving equivalent copy to DM780 when S/N is
      decreased by about 3-4dB.

      Now this was a quick eyeball comparison and hardly qualifies as a
      rigorous scientific test but it has satisfied me that there is an
      improvement over DM780 when running fldigi.

      --

      73 de Brian, WB6RQN
      Brian Lloyd - brian HYPHEN wb6rqn AT lloyd DOT com
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