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Re: Software Defined Superhet

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  • Stan
    ... system s ... better ... this. ... I seem to remember reading some place the QSD mixer had a noise figure in the area of 12 db ? Would this not be
    Message 1 of 8 , Nov 1, 2005
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      --- In softrock40@yahoogroups.com, "Bob Hillard" <rhillard@a...>
      wrote:
      >
      > The first device in the received signal's path determines the
      system's
      > noise figure. If it's a DBM, then the noise figure can't be any
      better
      > than 6 dB. Putting a low noise preamp in front of the DBM fixes
      this.
      >
      >

      I seem to remember reading some place the QSD mixer had a noise
      figure
      in the area of 12 db ? Would this not be acceptable except maybe
      above 28 mhz since the terrestial noise figure would be >15 db?

      It would be interesting to see a gain/noise chart by stages of the
      better commerical receivers when compared to the SDR-1000
      technologies.

      Does anyone know the maximum usable gain of a receiver(?) aren't we
      getting very close to that number in current HF technology?

      Are we not close to the point where the LO phase noise and front end
      IMD are the current limiting factors in a receiver design?

      I would be interested in reading others response in these area. It
      is an area in which I know very little.
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