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High Definition Audio Motherboard observations

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  • John Williams
    A while ago, I noted that I had a High Definition Audio chipset on my shack motherboard (Elite 945G-M3 with a 2 cpu em64T and 1G memory). I am running XP SP3
    Message 1 of 7 , Jan 28, 2011
    A while ago, I noted that I had a High Definition Audio chipset on my
    shack motherboard (Elite 945G-M3 with a 2 cpu em64T and 1G memory). I am
    running XP SP3 with MME sound support, at 96K.

    I have a few observations.

    First of all, there are 2 96K input channels. There are 8 192k output
    channels. It was suggested that I may encounter noise problems that
    would make it not much better than the AC97 prior gen soundcards. Well,
    I seem to be getting some pretty good results. It is not going to be as
    good as the remote usb soundcard implementations, but it is not bad.
    Here is a screenshot of GSDR listening to 40 meter from a softrock 40
    crystal controlled receiver. Noise floor is quite good, I think.

    Interested in your comments/observations welcome...

    John - ke5ssh
  • g8voip
    Hi John, I guess it really comes down to what you consider acceptable. Being totally honest, that looks extremely poor! With any reasonable sound card you
    Message 2 of 7 , Jan 28, 2011
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      Hi John,

      I guess it really comes down to what you consider acceptable.

      Being totally honest, that looks extremely poor!

      With any reasonable sound card you would only expect to see the few db variation in the noise floor across the whole of the 96kHz bandwidth. Looking at that, looks like 15 - 20dB variation, with some strange jumps in level, hard to really determine where the real noise floor is. Also tails off at the extreme edges suggesting the sound card bandwidth is dropping off before 48kHz.

      Take a look in the photo's section in my 'G8VOI' folder, there are a couple of Winrad screen grabs, one for 80m the other 6m. Whilst not perfect, they are probably more like what you should be expecting to see with a reasonable quality sound card.

      73, Bob G8VOI




      --- In softrock40@yahoogroups.com, John Williams <KE5SSH@...> wrote:
      >
      > A while ago, I noted that I had a High Definition Audio chipset on my
      > shack motherboard (Elite 945G-M3 with a 2 cpu em64T and 1G memory). I am
      > running XP SP3 with MME sound support, at 96K.
      >
      > I have a few observations.
      >
      > First of all, there are 2 96K input channels. There are 8 192k output
      > channels. It was suggested that I may encounter noise problems that
      > would make it not much better than the AC97 prior gen soundcards. Well,
      > I seem to be getting some pretty good results. It is not going to be as
      > good as the remote usb soundcard implementations, but it is not bad.
      > Here is a screenshot of GSDR listening to 40 meter from a softrock 40
      > crystal controlled receiver. Noise floor is quite good, I think.
      >
      > Interested in your comments/observations welcome...
      >
      > John - ke5ssh
      >
    • John Williams
      Thanks Bob for the comments. I posted this to validate/invalidate what I am seeing. I will take a look at your photos... One thing I noticed is that I cannot
      Message 3 of 7 , Jan 28, 2011
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        Thanks Bob for the comments. I posted this to validate/invalidate what I am seeing. I will take a look at your photos...

        One thing I noticed is that I cannot seem to understand how to use GSDR properly to calibrate receive image reduction. Rocky shows a completely different spectrum above the xtal freq.

        John

        On 1/28/2011 12:24 PM, g8voip wrote:
         

        Hi John,

        I guess it really comes down to what you consider acceptable.

        Being totally honest, that looks extremely poor!

        With any reasonable sound card you would only expect to see the few db variation in the noise floor across the whole of the 96kHz bandwidth. Looking at that, looks like 15 - 20dB variation, with some strange jumps in level, hard to really determine where the real noise floor is. Also tails off at the extreme edges suggesting the sound card bandwidth is dropping off before 48kHz.

        Take a look in the photo's section in my 'G8VOI' folder, there are a couple of Winrad screen grabs, one for 80m the other 6m. Whilst not perfect, they are probably more like what you should be expecting to see with a reasonable quality sound card.

        73, Bob G8VOI

        --- In softrock40@yahoogroups.com, John Williams <KE5SSH@...> wrote:
        >
        > A while ago, I noted that I had a High Definition Audio chipset on my
        > shack motherboard (Elite 945G-M3 with a 2 cpu em64T and 1G memory). I am
        > running XP SP3 with MME sound support, at 96K.
        >
        > I have a few observations.
        >
        > First of all, there are 2 96K input channels. There are 8 192k output
        > channels. It was suggested that I may encounter noise problems that
        > would make it not much better than the AC97 prior gen soundcards. Well,
        > I seem to be getting some pretty good results. It is not going to be as
        > good as the remote usb soundcard implementations, but it is not bad.
        > Here is a screenshot of GSDR listening to 40 meter from a softrock 40
        > crystal controlled receiver. Noise floor is quite good, I think.
        >
        > Interested in your comments/observations welcome...
        >
        > John - ke5ssh
        >

      • g8voip
        Hi John, I originally did checkout GSDR runnign with the SoftRock s, but I have since given up trying to fathom out what exactly they were trying to achieve in
        Message 4 of 7 , Jan 28, 2011
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          Hi John,

          I originally did checkout GSDR runnign with the SoftRock's, but I have since given up trying to fathom out what exactly they were trying to achieve in GSDR. Seems to be they are determined to do things differently and some of the choices are pretty poor.

          Later versions of PowerSDR, and I believe GSDR now uses one of these as its basis, has automatic 'Wide Band Image Rejection' (WBIR), so there is no manual adjustment.

          Certainly in Christos SV1EIA's demo PSDR v1.19.3.15 based on the FlexRadio v2.0 beta there are known problems with the WBIR function in the original Flex code. It occasionally ceases to work and requires a large signal (50dB above the noise floor) to kick it back into action.

          The other thing you will need to do is reverse the I/Q signals when using PSDR (GSDR) as it requires the opposite to Rocky and Winrad. That might account for your lack of image rejection.

          73, Bob G8VOI



          --- In softrock40@yahoogroups.com, John Williams <KE5SSH@...> wrote:
          >
          > Thanks Bob for the comments. I posted this to validate/invalidate what I
          > am seeing. I will take a look at your photos...
          >
          > One thing I noticed is that I cannot seem to understand how to use GSDR
          > properly to calibrate receive image reduction. Rocky shows a completely
          > different spectrum above the xtal freq.
          >
          > John
          >
          > On 1/28/2011 12:24 PM, g8voip wrote:
          > >
          > > Hi John,
          > >
          > > I guess it really comes down to what you consider acceptable.
          > >
          > > Being totally honest, that looks extremely poor!
          > >
          > > With any reasonable sound card you would only expect to see the few db
          > > variation in the noise floor across the whole of the 96kHz bandwidth.
          > > Looking at that, looks like 15 - 20dB variation, with some strange
          > > jumps in level, hard to really determine where the real noise floor
          > > is. Also tails off at the extreme edges suggesting the sound card
          > > bandwidth is dropping off before 48kHz.
          > >
          > > Take a look in the photo's section in my 'G8VOI' folder, there are a
          > > couple of Winrad screen grabs, one for 80m the other 6m. Whilst not
          > > perfect, they are probably more like what you should be expecting to
          > > see with a reasonable quality sound card.
          > >
          > > 73, Bob G8VOI
          > >
          > > --- In softrock40@yahoogroups.com
          > > <mailto:softrock40%40yahoogroups.com>, John Williams <KE5SSH@> wrote:
          > > >
          > > > A while ago, I noted that I had a High Definition Audio chipset on my
          > > > shack motherboard (Elite 945G-M3 with a 2 cpu em64T and 1G memory).
          > > I am
          > > > running XP SP3 with MME sound support, at 96K.
          > > >
          > > > I have a few observations.
          > > >
          > > > First of all, there are 2 96K input channels. There are 8 192k output
          > > > channels. It was suggested that I may encounter noise problems that
          > > > would make it not much better than the AC97 prior gen soundcards. Well,
          > > > I seem to be getting some pretty good results. It is not going to be as
          > > > good as the remote usb soundcard implementations, but it is not bad.
          > > > Here is a screenshot of GSDR listening to 40 meter from a softrock 40
          > > > crystal controlled receiver. Noise floor is quite good, I think.
          > > >
          > > > Interested in your comments/observations welcome...
          > > >
          > > > John - ke5ssh
          > > >
          > >
          > >
          >
        • Alan
          ... From: John Williams ... http://groups.yahoo.com/group/GenesisRadio/message/7328 Much like Bob says, make sure you have the latest version, it keeps being
          Message 5 of 7 , Jan 28, 2011
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            ----- Original Message -----
            From: "John Williams"
            >
            > One thing I noticed is that I cannot seem to understand how to use GSDR
            > properly to calibrate receive image reduction.

            http://groups.yahoo.com/group/GenesisRadio/message/7328

            Much like Bob says, make sure you have the latest version, it keeps being
            altered.


            73 Alan G4ZFQ
          • John Williams
            Thanks Alan, Is there an easy to build RF signal generator that can be used for this or should I keep my eye out for one on ebay? John
            Message 6 of 7 , Jan 29, 2011
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              Thanks Alan,

              Is there an easy to build RF signal generator that can be used for this or should I keep my eye out for one on ebay?

              John

              On 1/29/2011 1:28 AM, Alan wrote:
               


              ----- Original Message -----
              From: "John Williams"
              >
              > One thing I noticed is that I cannot seem to understand how to use GSDR
              > properly to calibrate receive image reduction.

              http://groups.yahoo.com/group/GenesisRadio/message/7328

              Much like Bob says, make sure you have the latest version, it keeps being
              altered.

              73 Alan G4ZFQ

            • Alan
              ... From: John Williams ... I sometimes use a Si570 with a controller. Lots of harmonics but it does what is
              Message 7 of 7 , Jan 29, 2011
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                ----- Original Message -----
                From: "John Williams"
                >
                > Is there an easy to build RF signal generator that can be used for this
                > or should I keep my eye out for one on ebay?
                >

                I sometimes use a Si570 with a <http://www.qsl.net/k5bcq/Kits/Kits.html>
                controller. Lots of harmonics but it does what is required.

                If you have a transceiver then running that into a dummy load, maybe with a
                Tee and a very short "antenna" will do the job.

                73 Alan G4ZFQ
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