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Re: [softrock40] Ensemble RXTX Rx I / Q

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  • Gordon JC Pearce
    ... Right, okay, here s a bit of lateral thinking for you: Get a 3.5mm stereo jack and a 3.5mm stereo line socket. Wire the plug and socket together crossed
    Message 1 of 13 , Apr 1, 2011
      On Thu, 2011-03-31 at 21:47 -0500, Joel Black wrote:
      >
      >
      > Yeah,
      >
      > I've done that - multiple times.

      Right, okay, here's a bit of lateral thinking for you:

      Get a 3.5mm stereo jack and a 3.5mm stereo line socket. Wire the plug
      and socket together crossed over. Use this to switch between crossed
      and uncrossed without constantly pratting about with the links.

      I'm sure someone said a while back that the Windows software was easier
      to use. I definitely heard that somewhere... ;-)

      Gordon MM0YEQ
    • g8voip
      Hi all, The biggest problem is people do not take the time to actually read or understand how the SDR gear works in its most basic way. A few minutes spent
      Message 2 of 13 , Apr 2, 2011
        Hi all,

        The biggest problem is people do not take the time to actually read or understand how the SDR gear works in its most basic way. A few minutes spent doing that would help no end in setting up and configuring both the hardware and software.

        For the I/Q signals there are simply only two choices on receive and transmit as far as the hardware is concerned. The most basic understanding will allow someone to easily determine whether what they are seeing and hearing is right or wrong, sidebands swapped over or spectrum display reversed high to low.

        I gave a talk at my local radio club just 6 weeks after first reading about SDR and acquiring a SoftRock kit from Tony. Although that was well over 5 years ago, the basic information is still valid and hopefully still of some use in helping explain the basics at a beginners level, which I certainly was myself at that time.

        http://home.ict.nl/~fredkrom/pe0fko/g8voi/

        Alan, G4ZFQ has started to refine the information on his web page and produced new pages specific to issues that seem to be the areas many have problems with and questions frequently arise. For the sound card and I/Q problems take a look at:

        http://sites.google.com/site/g4zfqradio/sdr-with-soundcard-basic-faults

        There is only so much those offering assistance can do to help, the rest is down to the individual themselves. After all, part of the process is or should be 'self learning'. Thats what amateur radio is all about, isn't it?

        73, Bob G8VOI
      • Joel Black
        Bob, et al, My problem was actually an LO that was not properly calibrated. Tony pointed me to that. I had followed the instructions at the build site by
        Message 3 of 13 , Apr 2, 2011
          Bob, et al,

          My problem was actually an LO that was not properly calibrated. Tony
          pointed me to that.

          I had followed the instructions at the build site by Robby, WB5RVZ, and
          they are great. I'm not complaining. However, the Si570 is a tad
          broader than I expected. So yes, I had "calibrated" it, but it wasn't
          even close... I'm getting to that.

          When I got to that step, I didn't use a freq counter as I should have, I
          used a local FM broadcast station. When I tuned the Si570 to 98.1MHz, I
          got full quieting on the FM radio (later, I tried this on 10MHz and got
          the same result). Problem is, the LO was 1.1kHz high. So, everything
          appeared to be LSB (1.5kHz below the carrier). No amount of me crossing
          and uncrossing the I and Q jumpers or moving soundcard inputs was going
          to solve that.

          Tony told me to go back and tune to WWV and re-calibrate. I did that
          and it all worked out. It has been stable since.

          73,
          Joel - W4JBB

          On 4/2/2011 2:12 AM, g8voip wrote:
          > Hi all,
          >
          > The biggest problem is people do not take the time to actually read or understand how the SDR gear works in its most basic way. A few minutes spent doing that would help no end in setting up and configuring both the hardware and software.
          >
          > For the I/Q signals there are simply only two choices on receive and transmit as far as the hardware is concerned. The most basic understanding will allow someone to easily determine whether what they are seeing and hearing is right or wrong, sidebands swapped over or spectrum display reversed high to low.
          >
          > I gave a talk at my local radio club just 6 weeks after first reading about SDR and acquiring a SoftRock kit from Tony. Although that was well over 5 years ago, the basic information is still valid and hopefully still of some use in helping explain the basics at a beginners level, which I certainly was myself at that time.
          >
          > http://home.ict.nl/~fredkrom/pe0fko/g8voi/
          >
          > Alan, G4ZFQ has started to refine the information on his web page and produced new pages specific to issues that seem to be the areas many have problems with and questions frequently arise. For the sound card and I/Q problems take a look at:
          >
          > http://sites.google.com/site/g4zfqradio/sdr-with-soundcard-basic-faults
          >
          > There is only so much those offering assistance can do to help, the rest is down to the individual themselves. After all, part of the process is or should be 'self learning'. Thats what amateur radio is all about, isn't it?
          >
          > 73, Bob G8VOI
          >
          >
          >
          >
          >
          >
          >
          > ------------------------------------
          >
          > Yahoo! Groups Links
          >
          >
          >
          >
          >
          > -----
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          --
          Joel

          "Common sense is like deodorant...
          Those who need it most don't use it."
          --Unknown
        • g8voip
          Hi Joel, I think the intention of the check with listening on a FM receiver is only tell you the Si570 is oscillating, certainly no way of determining the
          Message 4 of 13 , Apr 2, 2011
            Hi Joel,

            I think the intention of the check with listening on a FM receiver is only tell you the Si570 is oscillating, certainly no way of determining the frequency with any accuracy within a few 10's of kHz due to the width of the BC receivers filters.

            We can only work on the information given and you seemed to be pointing to a problem with resolving upper or lower sideband hence the focus by me and others on the I/Q settings. Simply having an error in the frequency calibration would not affect the signal you were trying to tune, only the absolute dial frequency.

            Frequency calibration is a completely separate process.

            Guess sometimes it is not possible to describe the problem or symptoms accurately enough to enable the correct solution to be given.

            Anyway, glad you managed to resolve your problem via a roundabout route.

            73, Bob G8VOI


            --- In softrock40@yahoogroups.com, Joel Black <w4jbb@...> wrote:
            >
            > Bob, et al,
            >
            > My problem was actually an LO that was not properly calibrated. Tony
            > pointed me to that.
            >
            > I had followed the instructions at the build site by Robby, WB5RVZ, and
            > they are great. I'm not complaining. However, the Si570 is a tad
            > broader than I expected. So yes, I had "calibrated" it, but it wasn't
            > even close... I'm getting to that.
            >
            > When I got to that step, I didn't use a freq counter as I should have, I
            > used a local FM broadcast station. When I tuned the Si570 to 98.1MHz, I
            > got full quieting on the FM radio (later, I tried this on 10MHz and got
            > the same result). Problem is, the LO was 1.1kHz high. So, everything
            > appeared to be LSB (1.5kHz below the carrier). No amount of me crossing
            > and uncrossing the I and Q jumpers or moving soundcard inputs was going
            > to solve that.
            >
            > Tony told me to go back and tune to WWV and re-calibrate. I did that
            > and it all worked out. It has been stable since.
            >
            > 73,
            > Joel - W4JBB
            >
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