Loading ...
Sorry, an error occurred while loading the content.

Re: [softrock40] PowerSDR Image Rejection adjustment

Expand Messages
  • 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 1 of 3 , Nov 3, 2006
    • 0 Attachment
      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 2 of 3 , Nov 3, 2006
      • 0 Attachment
        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
        >
      Your message has been successfully submitted and would be delivered to recipients shortly.