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PowerSDR Image Rejection adjustment

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  • Terry
    To Bill Tracey & others: First of all, thanks for all your help getting PowerSDR working for the Soft Rock RxTx unit. I have been working with Tony on the
    Message 1 of 3 , Nov 2, 2006
      To Bill Tracey & others:

      First of all, thanks for all your help getting PowerSDR working for
      the Soft Rock RxTx unit. I have been working with Tony on the
      transmitter output level. We think it's working fairly good now.

      I do have a question: I have been using PowerSDR with the SR exciter
      (stacked unit) and the RxTx unit to do testing. I now find the image
      is slightly too high, and wanted to adjust it.

      When I go to the DSP/image adjustments, I can control transmit phase
      and amplitude controls for SSB modes, but the adjustments don't seem
      to track to the CW mode. For example, I can put the unit in USB
      transmit, and enable the Tx Image Tone. I can then adjust the phase
      to -3 degrees and gain to -41.0 while watching a spectrum analyzer.
      These positions seem to drop the transmit image signal from -40db
      down to -60db down, or better. USB and LSB image rejection appear to
      be very good at that point. I have hit the apply settings.

      However, when I return to CW mode, the tranmsit image comes back up
      to only -40db down. Am I missing something? Is there something I
      need to do so the software implements these phase and gain
      adjustments on CW as well?

      I even tried to apply & exit PowerSDR, then reload it (which had
      worked on audio level adjustments.

      We need to be able to adjust Tx phase & gain adjustments to meet FCC
      specs of -43db with the Soft Rock RxTx units.

      Again, thanks for all your help in getting the software working.
      Once the image adjustments can be made, I believe the SR RxTx unit
      can be used on the air without concern of FCC specs.

      73s
      Terry
      WB4JFI
    • Robert McGwier
      OOOOooooooooopppppppssssss Man did we let that get by us. Terry this is not an overnight fix and will require more thought than a quick answer can provide.
      Message 2 of 3 , Nov 3, 2006
        OOOOooooooooopppppppssssss


        Man did we let that get by us. Terry this is not an overnight fix and
        will require more thought than a quick answer can provide.

        This is a design flaw.

        Bob
        N4HY




        Terry wrote:
        > To Bill Tracey & others:
        >
        > First of all, thanks for all your help getting PowerSDR working for
        > the Soft Rock RxTx unit. I have been working with Tony on the
        > transmitter output level. We think it's working fairly good now.
        >
        > I do have a question: I have been using PowerSDR with the SR exciter
        > (stacked unit) and the RxTx unit to do testing. I now find the image
        > is slightly too high, and wanted to adjust it.
        >
        > When I go to the DSP/image adjustments, I can control transmit phase
        > and amplitude controls for SSB modes, but the adjustments don't seem
        > to track to the CW mode. For example, I can put the unit in USB
        > transmit, and enable the Tx Image Tone. I can then adjust the phase
        > to -3 degrees and gain to -41.0 while watching a spectrum analyzer.
        > These positions seem to drop the transmit image signal from -40db
        > down to -60db down, or better. USB and LSB image rejection appear to
        > be very good at that point. I have hit the apply settings.
        >
        > However, when I return to CW mode, the tranmsit image comes back up
        > to only -40db down. Am I missing something? Is there something I
        > need to do so the software implements these phase and gain
        > adjustments on CW as well?
        >
        > I even tried to apply & exit PowerSDR, then reload it (which had
        > worked on audio level adjustments.
        >
        > We need to be able to adjust Tx phase & gain adjustments to meet FCC
        > specs of -43db with the Soft Rock RxTx units.
        >
        > Again, thanks for all your help in getting the software working.
        > Once the image adjustments can be made, I believe the SR RxTx unit
        > can be used on the air without concern of FCC specs.
        >
        > 73s
        > Terry
        > WB4JFI
        >
        >
        >
        >
        >
        >
        >
        > Yahoo! Groups Links
        >
        >
        >
        >
        >
        >


        --
        AMSAT Director and VP Engineering. Member: ARRL, AMSAT-DL,
        TAPR, Packrats, NJQRP, QRP ARCI, QCWA, FRC. ARRL SDR WG Chair
        "You see, wire telegraph is a kind of a very, very long cat.
        You pull his tail in New York and his head is meowing in Los
        Angeles. Do you understand this? And radio operates exactly
        the same way: you send signals here, they receive them there.
        The only difference is that there is no cat." - Einstein
      • Terry
        Thanks for looking into this Bob (N4HY) and Bill (KD5FTD). We soft rockers will certainly appreciate it. Unless I am mistaken, the same issue may be in the
        Message 3 of 3 , Nov 3, 2006
          Thanks for looking into this Bob (N4HY) and Bill (KD5FTD). We soft
          rockers will certainly appreciate it.

          Unless I am mistaken, the same issue may be in the receive as well.
          I have found that I cannot keep adjustments for CW in receive
          either. Plus, I can make the receive adjustments at one freq, but
          when I change freq, those adjustments don't work anymore.

          If the I/Q adjustments don't work in transmit CW, they may not in
          receive either.

          I don't think the Tx in CW is a serious issue as long as pone can
          adjust the channel gains and reduce the image. My RxTX CW image came
          down with under 30 seconds - and an analyzer.

          Thanks again!
          Terry
          WB4JFI

          --- In softrock40@yahoogroups.com, Robert McGwier <rwmcgwier@...>
          wrote:
          >
          >
          > OOOOooooooooopppppppssssss
          >
          >
          > Man did we let that get by us. Terry this is not an overnight fix
          and
          > will require more thought than a quick answer can provide.
          >
          > This is a design flaw.
          >
          > Bob
          > N4HY
          >
          >
          >
          >
          > Terry wrote:
          > > To Bill Tracey & others:
          > >
          > > First of all, thanks for all your help getting PowerSDR working
          for
          > > the Soft Rock RxTx unit. I have been working with Tony on the
          > > transmitter output level. We think it's working fairly good now.
          > >
          > > I do have a question: I have been using PowerSDR with the SR
          exciter
          > > (stacked unit) and the RxTx unit to do testing. I now find the
          image
          > > is slightly too high, and wanted to adjust it.
          > >
          > > When I go to the DSP/image adjustments, I can control transmit
          phase
          > > and amplitude controls for SSB modes, but the adjustments don't
          seem
          > > to track to the CW mode. For example, I can put the unit in USB
          > > transmit, and enable the Tx Image Tone. I can then adjust the
          phase
          > > to -3 degrees and gain to -41.0 while watching a spectrum
          analyzer.
          > > These positions seem to drop the transmit image signal from -40db
          > > down to -60db down, or better. USB and LSB image rejection
          appear to
          > > be very good at that point. I have hit the apply settings.
          > >
          > > However, when I return to CW mode, the tranmsit image comes back
          up
          > > to only -40db down. Am I missing something? Is there something
          I
          > > need to do so the software implements these phase and gain
          > > adjustments on CW as well?
          > >
          > > I even tried to apply & exit PowerSDR, then reload it (which had
          > > worked on audio level adjustments.
          > >
          > > We need to be able to adjust Tx phase & gain adjustments to meet
          FCC
          > > specs of -43db with the Soft Rock RxTx units.
          > >
          > > Again, thanks for all your help in getting the software working.
          > > Once the image adjustments can be made, I believe the SR RxTx
          unit
          > > can be used on the air without concern of FCC specs.
          > >
          > > 73s
          > > Terry
          > > WB4JFI
          > >
          > >
          > >
          > >
          > >
          > >
          > >
          > > Yahoo! Groups Links
          > >
          > >
          > >
          > >
          > >
          > >
          >
          >
          > --
          > AMSAT Director and VP Engineering. Member: ARRL, AMSAT-DL,
          > TAPR, Packrats, NJQRP, QRP ARCI, QCWA, FRC. ARRL SDR WG Chair
          > "You see, wire telegraph is a kind of a very, very long cat.
          > You pull his tail in New York and his head is meowing in Los
          > Angeles. Do you understand this? And radio operates exactly
          > the same way: you send signals here, they receive them there.
          > The only difference is that there is no cat." - Einstein
          >
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