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Re: [wsjtgroup] RE: multiple decodes jt 9 - WSJT-X v3563

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  • Rudy Benner
    Might need new tubes in the amp. r From: chas cartmel Sent: Friday, September 06, 2013 11:16 AM To: wsjtgroup@yahoogroups.com Subject: RE: [wsjtgroup] RE:
    Message 1 of 8 , Sep 6, 2013
    • 0 Attachment
      Might need new tubes in the amp.
       
      r
       
       
      Sent: Friday, September 06, 2013 11:16 AM
      Subject: RE: [wsjtgroup] RE: multiple decodes jt 9 - WSJT-X v3563
       
       

      Joe,
      Thought as much myself, he was 10db over 9 on the S meter whatever that
      signifies - never checked calibration. I think next time I hear a signal
      like this I will reduce the audio output of the rig and see what difference
      it makes after resetting the interface and software gains to get the 30db
      indication again.

      I am assuming though that it was a one off as i have never had (identified)
      such an issue on other modes such as PSK31 where the output from the rig to
      the interface is as it is now.

      73
      Charlie
      www.G4EST.me.uk

      -----Original Message-----
      From: wsjtgroup@yahoogroups.com [mailto:wsjtgroup@yahoogroups.com] On Behalf
      Of Joe Subich, W4TV
      Sent: 06 September 2013 16:02
      To: chas cartmel
      Cc: wsjtgroup@yahoogroups.com
      Subject: Re: [wsjtgroup] RE: multiple decodes jt 9 - WSJT-X v3563

      > He was the strongest on the band by a VERY large
      amount. A signal >
      strength equivalent to a PSK TX of around 50W under good propagation >
      conditions.

      If the IZ2DZN signal strength was "equivalent to a 50 W PSK" you are most
      certainly over driving the sound card. It would appear the sound card is
      close to, or even in, clipping.

      73,

      ... Joe, W4TV

      On 9/6/2013 9:54 AM, chas cartmel wrote:
      > Thanks Bruno, Joe and
      Mark
      >
      >
      >
      > Should have stated in my email that freq
      was 14.078. The IZ2DZN's power
      was unknown as although monitoring the station for a while this was not
      seen.
      >
      >
      >
      > He was the
      strongest on the band by a VERY large amount. A signal strength
      equivalent to a PSK TX of around 50W under good propagation conditions.
      >
      >
      >
      > 73
      >
      >
      Charlie
      >
      > www.G4EST.me.uk
      >
      >
      >
      > From:
      bruno.rod@... [mailto:bruno.rod@...]
      > Sent: 06 September 2013
      14:32
      > To: chas@...
      > Subject: RE: multiple decodes jt 9
      - WSJT-X v3563
      >
      >
      >
      > Hello Charlie.
      >
      >
      Yes, there they are.
      >
      >
      > 1246 -31 0.1 1188 @ CQ IK2DZN
      JN45
      >
      >
      >
      >
      > 1246 -21 0.1 1488 @ CQ IK2DZN
      JN45
      >
      >
      >
      >
      > 1246 19 0.1 1588 @ CQ IK2DZN
      JN45
      >
      >
      >
      >
      > 1246 -24 0.2 1688 @ CQ IK2DZN
      JN45
      >
      >
      >
      > The bigger are 40dB and 100 Hz apart. It
      seems a VERY VERY strong
      > signal (+19dB !! I have never seen something
      similar! What band? What
      > was the Power of IK2DZN?)
      >
      >
      Anyway 40dB is really a good level of suppression..
      >
      > It could be
      an issue of 100 Hz injection into your Audio Board, or could
      be a IK2DZN's issue with same level..
      >
      > 40 dB is anyway a very good
      suppression.. 3.1W to 1mW in powerlevel
      >
      > So, IMHO, do not worry
      about it.
      >
      > Best 73
      >
      > Bruno
      i3RGH
      >
      >

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    • Joe Subich, W4TV
      ... Depends on the rig obviously. However, if one has a background noise level of -130 dBm (typical urban/suburban on 20-15 meters), is not running AGC and
      Message 2 of 8 , Sep 6, 2013
      • 0 Attachment
        > Thought as much myself, he was 10db over 9 on the S meter whatever
        > that signifies - never checked calibration.

        Depends on the rig obviously. However, if one has a background noise
        level of -130 dBm (typical urban/suburban on 20-15 meters), is not
        running AGC and the receiver response is reasonably linear, the range
        is 67 dB from the noise floor to S9+10 (-130 dBm to -63 dBm).

        If the sound card has an effective 90 dB dynamic range (zero signal
        noise floor + hum to to clipping) and one sets the radio background
        noise 20 dB above the sound card noise floor (to give the software
        some opportunity to "work into the noise"), that leaves just 70 dB
        from "background" to clipping. If the sound card (external, internal
        or motherboard) has a high noise floor as some do (due to hum, power
        supply noise, poor decoupling, etc.) and one sets the "background"
        noise above the sound card noise floor, the sound card will clip
        (ADC overflow) on the strong signals.

        AGC helps by reducing the receiver gain on strong signals but that
        causes weak signals to "fall through the floor" in the presence of
        the stronger signals.

        73,

        ... Joe, W4TV


        On 9/6/2013 11:16 AM, chas cartmel wrote:
        > Joe,
        > Thought as much myself, he was 10db over 9 on the S meter whatever that
        > signifies - never checked calibration. I think next time I hear a signal
        > like this I will reduce the audio output of the rig and see what difference
        > it makes after resetting the interface and software gains to get the 30db
        > indication again.
        >
        > I am assuming though that it was a one off as i have never had (identified)
        > such an issue on other modes such as PSK31 where the output from the rig to
        > the interface is as it is now.
        >
        > 73
        > Charlie
        > www.G4EST.me.uk
        >
        > -----Original Message-----
        > From: wsjtgroup@yahoogroups.com [mailto:wsjtgroup@yahoogroups.com] On Behalf
        > Of Joe Subich, W4TV
        > Sent: 06 September 2013 16:02
        > To: chas cartmel
        > Cc: wsjtgroup@yahoogroups.com
        > Subject: Re: [wsjtgroup] RE: multiple decodes jt 9 - WSJT-X v3563
        >
        >
        > > He was the strongest on the band by a VERY large amount. A signal >
        > strength equivalent to a PSK TX of around 50W under good propagation >
        > conditions.
        >
        > If the IZ2DZN signal strength was "equivalent to a 50 W PSK" you are most
        > certainly over driving the sound card. It would appear the sound card is
        > close to, or even in, clipping.
        >
        > 73,
        >
        > ... Joe, W4TV
        >
        >
        > On 9/6/2013 9:54 AM, chas cartmel wrote:
        >> Thanks Bruno, Joe and Mark
        >>
        >>
        >>
        >> Should have stated in my email that freq was 14.078. The IZ2DZN's power
        > was unknown as although monitoring the station for a while this was not
        > seen.
        >>
        >>
        >>
        >> He was the strongest on the band by a VERY large amount. A signal strength
        > equivalent to a PSK TX of around 50W under good propagation conditions.
        >>
        >>
        >>
        >> 73
        >>
        >> Charlie
        >>
        >> www.G4EST.me.uk
        >>
        >>
        >>
        >> From: bruno.rod@... [mailto:bruno.rod@...]
        >> Sent: 06 September 2013 14:32
        >> To: chas@...
        >> Subject: RE: multiple decodes jt 9 - WSJT-X v3563
        >>
        >>
        >>
        >> Hello Charlie.
        >>
        >> Yes, there they are.
        >>
        >>
        >> 1246 -31 0.1 1188 @ CQ IK2DZN JN45
        >>
        >>
        >>
        >>
        >> 1246 -21 0.1 1488 @ CQ IK2DZN JN45
        >>
        >>
        >>
        >>
        >> 1246 19 0.1 1588 @ CQ IK2DZN JN45
        >>
        >>
        >>
        >>
        >> 1246 -24 0.2 1688 @ CQ IK2DZN JN45
        >>
        >>
        >>
        >> The bigger are 40dB and 100 Hz apart. It seems a VERY VERY strong
        >> signal (+19dB !! I have never seen something similar! What band? What
        >> was the Power of IK2DZN?)
        >>
        >> Anyway 40dB is really a good level of suppression..
        >>
        >> It could be an issue of 100 Hz injection into your Audio Board, or could
        > be a IK2DZN's issue with same level..
        >>
        >> 40 dB is anyway a very good suppression.. 3.1W to 1mW in powerlevel
        >>
        >> So, IMHO, do not worry about it.
        >>
        >> Best 73
        >>
        >> Bruno i3RGH
        >>
        >>
        >
        >
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        >
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        >
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        >
        >
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