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Re: [softrock40] Re: SR6 signal levels

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  • FRANCIS CARCIA
    I got similar numbers with my homebrew running about 500 hz. bw. Rob Campbell wrote: I managed to get a couple of hours after work today so
    Message 1 of 21 , Jun 1, 2006
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      I got similar numbers with my homebrew running about 500 hz. bw.

      Rob Campbell <gm6oqn@...> wrote:
      I managed to get a couple of hours after work today so here are the
      results of my testing so far:

      Signal (dBm)   Winrad display (dB)   Comment
      ------------   -------------------   -------
      -32             0                    multiple harmonics visible
      -32.2          -2                    S8
      -40            -5                    S7
      -50            -15                   S6
      -60            -25                   S5
      -70            -35                   S4
      -80            -45                   S3
      -90            -55                   S2
      -100           -65                   S1/S2
      -110           -75                   S1
      -120           -85                   <S1
      -130           -95                   see note 1 below
      -134           -**                   see note 2
      -135           -**                   see note 3

      Notes
      -----
      1. It was difficult to see any signal over the noise on the Spectrum
      display but the trace on the Waterfall was still distinct.
      2. No visible signal on the Spectrum, Waterfall becoming indistinct.
      3. Last traces of a signal still visible on the Waterfall.
      4. All measurements taken with an unmodulated carrier at 7.046MHz.
      5. Soundcard was a Crystal Fusion AC97 on the motherboard.
      6. Noise with no signal applied sits about the -100dB mark.
      7. Below -130dBm in it was hard to make out any audible tone but the
      waterfall display was still usable (probably only for slow morse).

      No measurements taken with Rocky yet but subjectively it looks
      pretty good. After doing a sweep with the signal generator (50 1kHz
      steps pausing for 1s at each step) to set the balance, image
      rejection is about 80dB.

      Hope this is useful.

      Rob, GM6OQN

      --- In softrock40@yahoogroups.com, "Rob Campbell" <gm6oqn@...> wrote:
      > --- In softrock40@yahoogroups.com, Bill Dumke <billd@> wrote:
      > >
      > > Rob,
      > >
      > > It would be interesting if you could use your signal generator
      to
      > make a
      > > standardized measurement of MDS looking for 3 dB (S+N)/N, then
      > noting
      > > the level you have going in from the generator.  This will give
      > the
      > > noise floor of the SoftRock.
      > >
      > > Bill, WB5TCO
      > >






    • FRANCIS CARCIA
      Nigel, I sent the daVinci code to the wrong place please send me a pm and I will try again. I deleted you mail so lost the address. frank Ford Peterson
      Message 2 of 21 , Jun 1, 2006
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        Nigel,
        I sent the daVinci code to the wrong place please send me a pm and I will try again.
        I deleted you mail so lost the address. frank

        Ford Peterson <ford@...> wrote:
        Bill wrote:

        > Francis,
        >
        > Thank you for posting that. Personally, I believe that is the biggest
        > single problem with these SDR type radios.
        >
        > Bill WB5TCO

        "that is" being phase noise of course.

        Actually, your comment is true, but not because of the "SDR type radios." These extremely simple receiver mixers are simply responding to the simply aweful Local Oscillators (by modern standards)that many of us are using to run the SR series mixers. Garbage-in / garbage-out as they say.

        My personal view is that there is likely no substitute for the multi-conversion receiver. We have become accustomed to enjoying the ability to QSY from the AM broadcast band up to 440MHz (and higher) with the touch of a button on most modern radios. I can see using an SDR type of mixer to acquire base-band data, and replace a large segment of a traditional radio using the sound card. But performance will be lack-luster at best when you QSY to any upper band without first performing a block-conversion of that band using traditional mixers and LOs. There is likely no substitute for traditional block conversion down to a reasonable frequency for the SDR to deal with. If you want real performance, then the focus of attention should be on the LO. Clean, frequency agile, spurious free, low-phase noise LOs is the name of the game. Use these nifty detectors as the final conversion from a relatively low frequency IF to your ears--and make that LO pristine clean of course.

        Ford-N0FP
        ford@...




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      • Alberto I2PHD
        ... Something went in saturation above -40 dBm....probably the opamps or the sound card. 73 Alberto I2PHD
        Message 3 of 21 , Jun 1, 2006
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          > Signal (dBm) Winrad display (dB) Comment
          > ------------ ------------------- -------
          > -32 0 multiple harmonics visible
          > -32.2 -2 S8
          > -40 -5 S7
          > -50 -15 S6
          > -60 -25 S5
          ---- snip ----

          Something went in saturation above -40 dBm....probably the opamps or the sound card.

          73 Alberto I2PHD
        • Bill Tracey
          Probably the sound card started saturating above -40 dbm -- the SR 6 hardware I ve measured will produce a 4.5Vpp signal with a -18 dbm input signal on 7 MHz.
          Message 4 of 21 , Jun 1, 2006
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            Probably the sound card started saturating above -40 dbm -- the SR 6
            hardware I've measured will produce a 4.5Vpp signal with a -18 dbm input
            signal on 7 MHz. Suspect the sound card saturates long before that.

            Cheers,

            Bill (kd5tfd)

            At 06:48 PM 6/1/2006, Alberto I2PHD wrote:
            > > Signal (dBm) Winrad display (dB) Comment
            > > ------------ ------------------- -------
            > > -32 0 multiple harmonics visible
            > > -32.2 -2 S8
            > > -40 -5 S7
            > > -50 -15 S6
            > > -60 -25 S5
            >---- snip ----
            >
            >Something went in saturation above -40 dBm....probably the opamps or the
            >sound card.
            >
            >73 Alberto I2PHD
          • FRANCIS CARCIA
            That is what I found. The OP amp gain jacks the signal to sound card saturation. Bill Tracey wrote: Probably the sound card started
            Message 5 of 21 , Jun 1, 2006
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              That is what I found. The OP amp gain jacks the signal to sound card saturation.

              Bill Tracey <kd5tfd@...> wrote:
              Probably the sound card started saturating above -40 dbm -- the SR 6
              hardware I've measured will produce a 4.5Vpp signal with a -18 dbm input
              signal  on 7 MHz.  Suspect the sound card saturates long before that.

              Cheers,

              Bill (kd5tfd)

              At 06:48 PM 6/1/2006, Alberto I2PHD wrote:
              > > Signal (dBm)   Winrad display (dB)   Comment
              > > ------------   -------------------   -------
              > > -32             0                    multiple harmonics visible
              > > -32.2          -2                    S8
              > > -40            -5                    S7
              > > -50            -15                   S6
              > > -60            -25                   S5
              >---- snip ----
              >
              >Something went in saturation above -40 dBm....probably the opamps or the
              >sound card.
              >
              >73  Alberto  I2PHD




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            • Sparkes, John
              Well, according to ONE, anyway...!________________________________From: softrock40@yahoogroups.com [mailto:softrock40@yahoogroups.com] On Behalf Of KD5NWA
              Message 6 of 21 , Jun 1, 2006
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                Well, according to ONE, anyway...!


                From: softrock40@yahoogroups.com [mailto:softrock40@yahoogroups.com] On Behalf Of KD5NWA
                Sent: Friday, 2 June 2006 02:17
                To: softrock40@yahoogroups.com
                Cc: softrock40@yahoogroups.com
                Subject: Re: [softrock40] phase noise

                According to some, phase noise and jitter is a vast conspiracy.

                At 11:49 AM 6/1/2006, Bill Dumke wrote:
                >Francis,
                >
                >Thank you for posting that. 
                Personally, I believe that is the biggest
                >single problem with these SDR
                type radios.
                >
                >Bill  WB5TCO
                >
                >FRANCIS CARCIA
                wrote:
                >
                > > I just found a good article on measuring phase
                noise. I have used the
                > > one with a mixer and HP8640B. It is uploaded
                into the file area.  gfz
                > >
                > >
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                www.qrpradio.com

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              • Robert Campbell
                Thanks, guys. Looks like the perfomance is OK and I haven t messed up in construction. I figured the harmonics were down to overdriving the soundcard input.
                Message 7 of 21 , Jun 2, 2006
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                  Thanks, guys.

                  Looks like the perfomance is OK and I haven't messed
                  up in construction. I figured the harmonics were down
                  to overdriving the soundcard input.

                  Just need to see what it does with an antenna now :-)

                  Rob GM6OQN

                  --- FRANCIS CARCIA <carcia@...> wrote:

                  > That is what I found. The OP amp gain jacks the
                  > signal to sound card saturation.
                  >
                  > Bill Tracey <kd5tfd@...> wrote: Probably the
                  > sound card started saturating above -40 dbm -- the
                  > SR 6
                  > hardware I've measured will produce a 4.5Vpp signal
                  > with a -18 dbm input
                  > signal on 7 MHz. Suspect the sound card saturates
                  > long before that.
                  >
                  > Cheers,
                  >
                  > Bill (kd5tfd)
                  >
                  > At 06:48 PM 6/1/2006, Alberto I2PHD wrote:
                  > > > Signal (dBm) Winrad display (dB) Comment
                  > > > ------------ ------------------- -------
                  > > > -32 0 multiple
                  > harmonics visible
                  > > > -32.2 -2 S8
                  > > > -40 -5 S7
                  > > > -50 -15 S6
                  > > > -60 -25 S5
                  > >---- snip ----
                  > >
                  > >Something went in saturation above -40
                  > dBm....probably the opamps or the
                  > >sound card.
                  > >
                  > >73 Alberto I2PHD
                  >
                  >
                  >
                  >
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