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Re: Arrived! SoftRock Ver. 6 40/80 M

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  • gw0etf
    ... zero ... the ... center ... Tom (and Milt...), If it s any use, I ve just uploaded an article I ve just written for our club newsletter which includes my
    Message 1 of 4 , Jul 27, 2006
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      --- In softrock40@yahoogroups.com, Milt Cram <w8nue@...> wrote:
      >
      > Tom wrote:

      > >
      > > Now I need to find a place on the web that can explain the theory of
      > > quadrature detection WITHOUT using mathematics :-)
      > >

      > >
      > > Thanks again to Tony for this great little rig. 73,
      > >
      > > Tom Curtola
      > > VA3TY
      > > Toronto, Ontario - Canada
      > >
      > >
      > Tom,
      >
      > The signal at the center of your display is due to the soundcard. It
      > corresponds to the xtal frequency used in your Softrock and is the
      "zero
      > beat" frequency of the IQ detector. If the sound card has little noise
      > around DC and has zero DC offset, the garbage in the center of the
      > spectrum will be minimal. My on-board sound card has a fairly large DC
      > offset and consequently shows a fairly large signal at the center of
      the
      > spectrum. An external USB SB Live has a much lower signal at the
      center
      > of the display.
      >
      > The neat thing about the Softrock and IQ detection is that it can
      > separate signals that are below the oscillator frequency, from those
      > that are above it. A standard direct conversion receiver can't do this
      > because it does not have both I and Q signals-- the IQ detection can
      > distinguish between positive and negative frequencies.
      >
      > Enjoy the Softrock and the many great software packages.
      >
      > 73, Milt
      > W8NUE
      >

      Tom (and Milt...),
      If it's any use, I've just uploaded an article I've just written for
      our club newsletter which includes my non-technical interpretation of
      the underlying magic in this mighty midget of a kit.
      It's in the files section and is called Softrock.doc.

      Just about to play with the second kit using a DDS60 as alternative
      clock source; this Softrock kit must be the best value for 'grins per
      dollar' ever..!
      73, Stewart Rolfe, GW0ETF
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