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8.33 Panadapter - What is Rocky's RX I/Q Tab Balance About?

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  • ve9xyz
    I am experimenting with a 8.83 MHz IF Panapter fromm a CSoltrock Lite II and don t see any detail of what the RX I/Q Balance tab does in Rocky s web guide.
    Message 1 of 5 , Jan 5, 2013
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      I am experimenting with a 8.83 MHz IF Panapter fromm a CSoltrock Lite II and don't see any detail of what the RX I/Q Balance tab does in Rocky's web guide.

      Ther are check-boxes for "collect data", and "correct balance" and 2 interesting graphs - can someone explain what I am looking at and why I'd want to collect data or reset this ?

      Thanks,

      Kevin

      VE9-XYZ
    • warrenallgyer
      Here is my understanding, partially from reading Alex s notes and partially from experience. There is some algorithm within Rocky that automatically corrects
      Message 2 of 5 , Jan 5, 2013
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        Here is my understanding, partially from reading Alex's notes and partially from experience. There is some algorithm within Rocky that automatically corrects IQ imbalance under certain conditions. It seems to look for strong, continuous signals and then look for the IQ image of these signals. It then automatically applies small corrections to both phase and gain while monitoring the level of the image. the lines you are seeing are the history of these "tries". At some point it stops, usually because it has successfully nulled the image or the signal has gone away, or it just gives up.

        The history of the "try" remains and is stored in the Rocky config files for use the next time you go to that band segment as a starting point. When you "reset" you clear this history and start from scratch which, I find anyway, usually gets you to the null quicker when you have changed something, like the sound card. The algorithm doesn't need to incorporate the history under different conditions in its' calculations.

        I leave the "collect data' and 'correct balance' selected at all times so it is always correcting and I just don't worry about receive IQ balance with this program.

        Don't take this as gospel..... a lot of it is intuition and observation. But I think that is how it works.

        Regards,

        Warren Allgyer - W8TOD

        --- In softrock40@yahoogroups.com, "ve9xyz" wrote:
        >
        > I am experimenting with a 8.83 MHz IF Panapter fromm a CSoltrock Lite II and don't see any detail of what the RX I/Q Balance tab does in Rocky's web guide.
        >
        > Ther are check-boxes for "collect data", and "correct balance" and 2 interesting graphs - can someone explain what I am looking at and why I'd want to collect data or reset this ?
        >
        > Thanks,
        >
        > Kevin
        >
        > VE9-XYZ
        >
      • Alan
        ... Subject: [softrock40] Re: 8.33 Panadapter - What is Rocky s RX I/Q Tab Balance About? I ll just add that the software does not need to search for the
        Message 3 of 5 , Jan 5, 2013
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          ----- Original Message -----
          Subject: [softrock40] Re: 8.33 Panadapter - What is Rocky's RX I/Q Tab Balance About?

          I'll just add that the software does not need to search for the image.
          It is exactly opposite centre on the unzoomed display.
          If the signal you want is 10KHz above the centre LO frequency then the image will be 10KHz below centre.
          Normally you will not see this wth Rocky, image cancel is ticked by default.
          The charts produced by Rocky show how the phase and gain vary across the band. On receive Rocky applies optimum rejection across the
          band.
          Other software, notably HDSDR, has no automatic adjustment. In a way this is good, it gives practice for TX setting. Sometimes at
          first it may seem impossible to get a null.

          When transmitting this is exactly the same. But there is never any automatic cancelling. You have to use a receiver and cancelling
          controls to reduce this to a minimum.
          This really is mandatory, a faulty setup may have no image rejection. Or the IQ lines may be crossed. With no adjustment the image
          may only be 20dB below the wanted signal. Even less than that if the controls are set wrongly.

          73 Alan G4ZFQ

          > Here is my understanding, partially from reading Alex's notes and partially from experience. There is some algorithm within Rocky
          > that automatically corrects IQ imbalance under certain conditions. It seems to look for strong, continuous signals and then look
          > for the IQ image of these signals. It then automatically applies small corrections to both phase and gain while monitoring the
          > level of the image. the lines you are seeing are the history of these "tries". At some point it stops, usually because it has
          > successfully nulled the image or the signal has gone away, or it just gives up.
          >
          > The history of the "try" remains and is stored in the Rocky config files for use the next time you go to that band segment as a
          > starting point. When you "reset" you clear this history and start from scratch which, I find anyway, usually gets you to the null
          > quicker when you have changed something, like the sound card. The algorithm doesn't need to incorporate the history under
          > different conditions in its' calculations.
          >
          > I leave the "collect data' and 'correct balance' selected at all times so it is always correcting and I just don't worry about
          > receive IQ balance with this program.
          >
          > Don't take this as gospel..... a lot of it is intuition and observation. But I think that is how it works.
          >
          > Regards,
          >
          > Warren Allgyer - W8TOD
          >
          > --- In softrock40@yahoogroups.com, "ve9xyz" wrote:
          >>
          >> I am experimenting with a 8.83 MHz IF Panapter fromm a CSoltrock Lite II and don't see any detail of what the RX I/Q Balance tab
          >> does in Rocky's web guide.
          >>
          >> Ther are check-boxes for "collect data", and "correct balance" and 2 interesting graphs - can someone explain what I am looking
          >> at and why I'd want to collect data or reset this ?
          >>
        • Alan
          ... Subject: [softrock40] Re: 8.33 Panadapter - What is Rocky s RX I/Q Tab Balance About? Now I remember my page
          Message 4 of 5 , Jan 5, 2013
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            ----- Original Message -----
            Subject: [softrock40] Re: 8.33 Panadapter - What is Rocky's RX I/Q Tab Balance About?



            Now I remember my page https://sites.google.com/site/g4zfqradio/sdr-with-soundcard-basic-faults has a few pictures of Rocky and
            images.

            And the Rocky web site "Advanced" link has a good image rejection description.

            73 Alan G4ZFQ
          • warrenallgyer
            Ahaa! Thanks for the correction Alan. The graphs are across the bandpass and not historical data. That makes more sense. Warren Allgyer - W8TOD
            Message 5 of 5 , Jan 6, 2013
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              Ahaa! Thanks for the correction Alan. The graphs are across the bandpass and not historical data. That makes more sense.

              Warren Allgyer - W8TOD

              --- In softrock40@yahoogroups.com, "Alan" wrote:
              >
              >
              > ----- Original Message -----
              > Subject: [softrock40] Re: 8.33 Panadapter - What is Rocky's RX I/Q Tab Balance About?
              >
              >
              >
              > Now I remember my page https://sites.google.com/site/g4zfqradio/sdr-with-soundcard-basic-faults has a few pictures of Rocky and
              > images.
              >
              > And the Rocky web site "Advanced" link has a good image rejection description.
              >
              > 73 Alan G4ZFQ
              >
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