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1903Re: [dxatlas] "Skimmer Server" with QS1R Receiver

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  • Wes Cosand
    Apr 9, 2010
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      Jeffrey:

      The QS1R has a large FPGA chip on the board. Alex has written code that
      runs on the FPGA chip and creates the seven receivers. The signals are then
      sent by USB to the computer where they are processed. So you have seven
      continuous streams of data of up to 192 kHz each.

      In my hands the system has been pretty robust. The QS1R runs the rf from
      the antenna almost directly into the ADC chip so there is no RF
      pre-amplification. Consequently, it is a little insensitive, especially on
      the higher bands. Since the front end is wide open, if you add lots of
      pre-amplification and you are near broadcast transmitters, you get into IMD
      problems. Some of us are using an 11 db preamp from Clifton Laboratories
      which seems pretty good. Others are using pre-amps with a little more gain.
      Clifton Laboratories also has a high pass filter for receivers with
      broadcast band issues.

      I put the system on a Intel I7 computer running Windows 7 64 bit despite the
      fact that this is not an officially supported OS. For reasons I do not
      understand, the Skimmer Server application begins to report "CPU Overload"
      and starts to decode only a fraction of the signals when I reach about 1100
      simultaneous decoders. This is despite the fact that the machine and the
      application are reporting only about 6 to 8% CPU load. I do not know where
      the bottleneck is. This issue may be unique to my machine. Perhaps a 32 bit
      machine would be better.

      Email me if I can be of further help.

      Wes, WZ7I


      Wes Cosand
      6299 Route 413
      PO Box 349
      Pipersville, PA 18947
      267-864-6161
      www.wz7i.com
      CW Skimmer CQ spots: ve7cc.net:7333


      On Fri, Apr 9, 2010 at 9:16 AM, jmaass_moose <jmaass@...> wrote:

      >
      >
      >
      > How does the QS1R receiver with "Skimmer Server" provide up to seven bands
      > at a time?
      >
      > Does it hop from band-to-band in sequence, or does it cover seven bands
      > simultaneously?
      >
      > Who is using "Skimmer Server" with a QS1R? Good experience? Reliable
      > hardware?
      >
      > We are planning an unattended installation of a Skimmer site on Curacao.
      > We've been leaning towards what we've used before (multiple SDR-IQ
      > receivers), but the QS1R is a more economical solution.
      >
      >
      >


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