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Automatic IQ correction now works with RTL-SDR

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  • sdrsharp
    Hi all, After a day of investigation and testing, Steve M. from the Osmocom team has solved an issue that was preventing SDR# s IQ correction from working
    Message 1 of 6 , Jun 3, 2012
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      Hi all,

      After a day of investigation and testing, Steve M. from the Osmocom team has solved an issue that was preventing SDR#'s IQ correction from working properly. The spectrum was shifted by about 2kHz and thus image correction wasn't working at all. This has changed with the latest release of librtlsdr (rtlsdr.dll) which is included in the development package of SDR#. Now even these cheap DVB-T dongle have over 80dB image rejection. Isn't that cool?
      Here are some screenshots of the FM broadcast band with IQ correction in action:
      http://sdrsharp.com/downloads/rtl_without_iq_correction.png
      http://sdrsharp.com/downloads/rtl_with_iq_correction.png

      Youssef
    • dosfan1234
      Outstanding work. Well done to all involved! This is the sort of work that makes SDR# the only viable software on Windows for these devices. Ian
      Message 2 of 6 , Jun 3, 2012
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        Outstanding work. Well done to all involved!

        This is the sort of work that makes SDR# the only viable software on Windows for these devices.

        Ian

        --- In SDRSharp@..., "sdrsharp" <sdrsharp@...> wrote:
        >
        > Hi all,
        >
        > After a day of investigation and testing, Steve M. from the Osmocom team has solved an issue that was preventing SDR#'s IQ correction from working properly. The spectrum was shifted by about 2kHz and thus image correction wasn't working at all. This has changed with the latest release of librtlsdr (rtlsdr.dll) which is included in the development package of SDR#. Now even these cheap DVB-T dongle have over 80dB image rejection. Isn't that cool?
        > Here are some screenshots of the FM broadcast band with IQ correction in action:
        > http://sdrsharp.com/downloads/rtl_without_iq_correction.png
        > http://sdrsharp.com/downloads/rtl_with_iq_correction.png
        >
        > Youssef
        >
      • sdrsharp
        Hi, It was just a byte that wasn t written in the DDC register. Once Steve fixed it, this seemed to work spontaneously. I didn t have to change anything in
        Message 3 of 6 , Jun 4, 2012
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          Hi,

          It was just a byte that wasn't written in the DDC register. Once Steve fixed it, this seemed to work spontaneously. I didn't have to change anything in SDR#. I believe it's hard to write a driver for closed source hardware. So yes, that's an oustanding work.
          Btw, have you had a look to this post? http://www.reddit.com/r/RTLSDR/comments/uje3q/sample_python_code_and_results_for_iq_correction/

          Youssef

          --- In SDRSharp@..., "dosfan1234" <mm6dos@...> wrote:
          >
          >
          > Outstanding work. Well done to all involved!
          >
          > This is the sort of work that makes SDR# the only viable software on Windows for these devices.
          >
          > Ian
          >
          > --- In SDRSharp@..., "sdrsharp" <sdrsharp@> wrote:
          > >
          > > Hi all,
          > >
          > > After a day of investigation and testing, Steve M. from the Osmocom team has solved an issue that was preventing SDR#'s IQ correction from working properly. The spectrum was shifted by about 2kHz and thus image correction wasn't working at all. This has changed with the latest release of librtlsdr (rtlsdr.dll) which is included in the development package of SDR#. Now even these cheap DVB-T dongle have over 80dB image rejection. Isn't that cool?
          > > Here are some screenshots of the FM broadcast band with IQ correction in action:
          > > http://sdrsharp.com/downloads/rtl_without_iq_correction.png
          > > http://sdrsharp.com/downloads/rtl_with_iq_correction.png
          > >
          > > Youssef
          > >
          >
        • rainerfeldkamp
          Hi Youssef, Since I m still waiting for my E4000 device to arrive, I bought a LogiLink (VID=1d19, PID=1101 with tuner=fc0013). With Windows XP, this device is
          Message 4 of 6 , Jun 4, 2012
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            Hi Youssef,

            Since I'm still waiting for my E4000 device to arrive, I bought a LogiLink (VID=1d19, PID=1101 with tuner=fc0013). With Windows XP, this device is properly recognised as Devatek DK in the front end window, but the tuner is indicated as FC0013 (capital letters).

            IQ correction seems to be erratic at best, and with a step size of f.i. 100kHz, for each mouse wheel click, the center frequency changes by 300kHz whereas the frequency changes only by 30HZ per click.

            Apart therefrom, SDR# performs excellently.

            No similar problem with WR+ where I could add fc0013 to the 'Hint'.

            Does this mean that only E4000 tuners are supported by SDR#, or is there any problem with the rtlsdr.dll ?

            Regards,

            Rainer


            --- In SDRSharp@..., "sdrsharp" <sdrsharp@...> wrote:
            >
            > Hi all,
            >
            > After a day of investigation and testing, Steve M. from the Osmocom team has solved an issue that was preventing SDR#'s IQ correction from working properly. The spectrum was shifted by about 2kHz and thus image correction wasn't working at all. This has changed with the latest release of librtlsdr (rtlsdr.dll) which is included in the development package of SDR#. Now even these cheap DVB-T dongle have over 80dB image rejection. Isn't that cool?
            > Here are some screenshots of the FM broadcast band with IQ correction in action:
            > http://sdrsharp.com/downloads/rtl_without_iq_correction.png
            > http://sdrsharp.com/downloads/rtl_with_iq_correction.png
            >
            > Youssef
            >
          • g33ddc
            ...and with a step size of f.i. 100kHz, for each mouse wheel click, the center frequency changes by 300kHz whereas the frequency changes only by 30HZ per
            Message 5 of 6 , Jun 4, 2012
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              "...and with a step size of f.i. 100kHz, for each mouse wheel click, the center frequency changes by 300kHz whereas the frequency changes only by 30HZ per click."

              I also noticed this erratic behavior but I doubt it's related to I&Q correction.


              --- In SDRSharp@..., "rainerfeldkamp" <feldkamp@...> wrote:
              >
              >
              >
              > Hi Youssef,
              >
              > Since I'm still waiting for my E4000 device to arrive, I bought a LogiLink (VID=1d19, PID=1101 with tuner=fc0013). With Windows XP, this device is properly recognised as Devatek DK in the front end window, but the tuner is indicated as FC0013 (capital letters).
              >
              > IQ correction seems to be erratic at best, and with a step size of f.i. 100kHz, for each mouse wheel click, the center frequency changes by 300kHz whereas the frequency changes only by 30HZ per click.
              >
              > Apart therefrom, SDR# performs excellently.
              >
              > No similar problem with WR+ where I could add fc0013 to the 'Hint'.
              >
              > Does this mean that only E4000 tuners are supported by SDR#, or is there any problem with the rtlsdr.dll ?
              >
              > Regards,
              >
              > Rainer
              >
              >
              > --- In SDRSharp@..., "sdrsharp" <sdrsharp@> wrote:
              > >
              > > Hi all,
              > >
              > > After a day of investigation and testing, Steve M. from the Osmocom team has solved an issue that was preventing SDR#'s IQ correction from working properly. The spectrum was shifted by about 2kHz and thus image correction wasn't working at all. This has changed with the latest release of librtlsdr (rtlsdr.dll) which is included in the development package of SDR#. Now even these cheap DVB-T dongle have over 80dB image rejection. Isn't that cool?
              > > Here are some screenshots of the FM broadcast band with IQ correction in action:
              > > http://sdrsharp.com/downloads/rtl_without_iq_correction.png
              > > http://sdrsharp.com/downloads/rtl_with_iq_correction.png
              > >
              > > Youssef
              > >
              >
            • sdrsharp
              IQ correction seems to be erratic at best You re confusing frequency steps and IQ correction. Google is your friend. Historically, SDR# was built for HF SDRs
              Message 6 of 6 , Jun 5, 2012
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                "IQ correction seems to be erratic at best" You're confusing frequency steps and IQ correction. Google is your friend.
                Historically, SDR# was built for HF SDRs where 1kHz step is somehow large enough for the narrow bandwidth of the receivers. Now it makes sense to add more convenient steps and change them automatically for every mode. I did it for the center freq but left the VFO frequency for fine tuning. Have you ever tried to tune a SSB signal with 10kHz steps? Anyway... I'll see how to combine the two functionalities in a convenient fashion.
                Concerning the FC0013 tuner, I'll forward your question to the Osmocom team. But as fasas I know, that tuner works flawlessly with the latest version of rtlsdr.dll. May be you need to update?

                Youssef

                --- In SDRSharp@..., "rainerfeldkamp" <feldkamp@...> wrote:
                >
                >
                >
                > Hi Youssef,
                >
                > Since I'm still waiting for my E4000 device to arrive, I bought a LogiLink (VID=1d19, PID=1101 with tuner=fc0013). With Windows XP, this device is properly recognised as Devatek DK in the front end window, but the tuner is indicated as FC0013 (capital letters).
                >
                > IQ correction seems to be erratic at best, and with a step size of f.i. 100kHz, for each mouse wheel click, the center frequency changes by 300kHz whereas the frequency changes only by 30HZ per click.
                >
                > Apart therefrom, SDR# performs excellently.
                >
                > No similar problem with WR+ where I could add fc0013 to the 'Hint'.
                >
                > Does this mean that only E4000 tuners are supported by SDR#, or is there any problem with the rtlsdr.dll ?
                >
                > Regards,
                >
                > Rainer
                >
                >
                > --- In SDRSharp@..., "sdrsharp" <sdrsharp@> wrote:
                > >
                > > Hi all,
                > >
                > > After a day of investigation and testing, Steve M. from the Osmocom team has solved an issue that was preventing SDR#'s IQ correction from working properly. The spectrum was shifted by about 2kHz and thus image correction wasn't working at all. This has changed with the latest release of librtlsdr (rtlsdr.dll) which is included in the development package of SDR#. Now even these cheap DVB-T dongle have over 80dB image rejection. Isn't that cool?
                > > Here are some screenshots of the FM broadcast band with IQ correction in action:
                > > http://sdrsharp.com/downloads/rtl_without_iq_correction.png
                > > http://sdrsharp.com/downloads/rtl_with_iq_correction.png
                > >
                > > Youssef
                > >
                >
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