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10479Re: [perseus_SDR] PERSEUS sensitivity

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  • Marco IK1ODO -2
    Jul 1, 2010
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      Hi Roelof,

      interesting data. Some week ago I did several days of activity in 10m
      in WSPR. My antenna is a seven-band vertical (ECO 7+) so obviously
      not fantastic.
      Checking at various times of the day, I have been always able to
      detect an increase in noise by switching from a 50 ohm termination to
      the antenna; so the Perseus seems sensitive enough for operation in
      suburban areas (I live in a residential village, but every house
      seems to have three PC and three plasma TVs, not counting LED lightnings :-()
      However it seems that other stations receive my signal with better
      S/N, so other places are clearly quieter. I did some experiment with
      a nice Norton differential amplifier, low noise (3 dB NF) and 10 dB
      gain (an ANZAC AM-109) and put it before Perseus. The S/N indeed is
      now marginally better, let say 3 dB in average. However, the AM-109
      dissipates about 10W... :-) linearity and low noise have a price!

      73 - Marco IK1ODO - JN35sa


      At 18:18 01-07-10, you wrote:
      >Hello all,
      >
      >On paper the 16 dB noise figure of PERSEUS is something that looks a bit
      >cheap.
      >As I understand it, this is a design trade off to maintain the good strong
      >signal handling capabilities of the A/D convertor at the receiver front
      >end.
      >However, how "bad" is it in practice?
      >
      >Here you can download a 42.6 MB PERSEUS recording:
      >
      >http://www.ndb.demon.nl/IW2DZX/
      >
      >It is a 400 kHz wide recording tuned to the 500 milliwatt (!) beacon
      >signal of Aldo Moroni, IW2DZX from Italy as received in the Netherlands.
      >You can also tune around and see what a nice tool PERSEUS waterfall
      >display is to spot the fast fading in and out 28 MHz beacon stations.
      >
      >My antenna is a 2 x 16 m long doublet with 11 meter open feedline, matched
      >with a balanced ATU.
      >
      >Best regards,
      >Roelof Bakker, pa0rdt
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