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Re: [wsjtgroup] Ongoing Audio Questions

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  • Joe Subich, W4TV
    ... microphone vs. Line is only a matter of the USB CODEC used - one would assume the hardware designer chose the appropriate input voltage level (and
    Message 1 of 8 , Aug 29, 2013
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      > The SignaLink USB, at least with Windows 7 does not have a "line"
      > input - only "microphone".

      "microphone" vs. "Line" is only a matter of the USB CODEC used -
      one would assume the hardware designer chose the appropriate
      input voltage level (and internal gain settings in the CODEC)
      for the device being used.

      > The first thing I noticed was that to bring the audio level from the
      > SignaLink (step 7) up to 20 or 25 dB I had to turn it all the way up.
      > May very well be due to the fact that I turned the Windows input from
      > 100% down to 65%.

      Then increase the Windows input. In theory increasing the input on
      the sound card driver would make it easier to overdrive the CODEC but
      perhaps your device is gain limited (or the transceiver is output
      limited).

      > Does the position of the cursor in the waterfall have any bearing on
      > what is decoded?

      Read K1JT's documentation - page 25:

      > For operator convenience the decoder goes through its full procedure
      > twice: first over a narrow range around the selected Rx frequency,
      > and then in the full displayed frequency range (or in JT9+JT65 mode,
      > the displayed range above the blue JT65 nnnn JT9 marker).

      When "dual mode" decode is enabled, the process becomes - 1) decode at
      the cursor, 2) decode broadly the mode selected for transmit (above or
      below the JT65/JT9 dividing line as appropriate), 3) decode broadly
      the "other" mode.

      > If the immediate area under the cursor is decoded more vigorously,
      > maybe that is part of my problem?

      I don't know why you should have any more problem decoding the area
      of the cursor than the broad decode but it might be that your sound
      card is noisy or unstable. That brand does not have a good reputation
      for being exactly "clean" or have a particularly flat audio response:
      http://www.frenning.dk/OZ1PIF_HOMEPAGE/SignaLinkUSB-mods.html
      http://www.youtube.com/watch?v=at9z0kDTs_w
      http://www.youtube.com/watch?v=kgqxq5_o7sI
      http://freedv.org/tiki-index.php?page=Tigertronics

      73,

      ... Joe, W4TV


      On 8/29/2013 7:32 PM, Dave 'Doc' Corio wrote:
      > Joe, I really appreciate the detailed response! Setting up the
      > system per your email, and one big thought occurred to me. The SignaLink
      > USB, at least with Windows 7 does not have a "line" input - only
      > "microphone". If I recall, mic is much higher input than line, so
      > therefore I MAY very well have been over-driving the decoder, simply by
      > having the Windows input gain set at max.
      >
      > The first thing I noticed was that to bring the audio level from
      > the SignaLink (step 7) up to 20 or 25 dB I had to turn it all the way
      > up. May very well be due to the fact that I turned the Windows input
      > from 100% down to 65%.
      >
      > Going to try this for a bit & see if I notice any improvement in my
      > decode problems. Let me ask one more question, either of you or anyone
      > in the group who may know:
      >
      > Does the position of the cursor in the waterfall have any bearing
      > on what is decoded? In other words, is the area where the
      > transmit/receive indicators are located decoded any different than the
      > rest of the waterfall? My ongoing problem has been losing decodes of the
      > station I'm trying to work, while everyone else within the bandwidth
      > decodes just fine. If the immediate area under the cursor is decoded
      > more vigorously, maybe that is part of my problem?
      >
      > In the meantime, trying these new settings!!
      >
      > Thanks Again!!
      > 73
      > Doc
      > KB3MOW
      >
      > On 8/29/2013 4:53 PM, Joe Subich, W4TV wrote:
      >>
      >>
      >> Here is the way I set-up receive audio - regardless of the sound card
      >> or transceiver:
      >>
      >> 1) start with the rig off
      >> 2) turn the *hardware* input level of your sound card to zero or
      >> disconnect the audio input to the sound card.
      >> 3) Set the Windows 7/Windows 8 "Sounds" Control Panel | Recording
      >> Devices | <sound card> | Line | Levels to between 50 and 80
      >> 4) Set Wide graph to Zero = 0, Gain = 0, Slope = 0.0 and select
      >> "Current"
      >> 5) Adjust the audio slider in the WSJT-X main window until the
      >> main window audio level is 0 dB. This sets the WSJT-X input
      >> gain to unity and matches the WSJT-X noise floor to the no
      >> signal noise floor of your sound card.
      >> 6) connect audio from your transceiver to the sound card if you
      >> disconnected it in step 2
      >> 5) turn on the transceiver, select a dummy load or disconnect
      >> the antenna input and adjust the *hardware* input level (level
      >> from the radio if the rig has an adjustable output or the "RX
      >> level" on your interface) until the WSJT-X Main audio level is
      >> between 20 and 25 dB.
      >> 6) connect your antenna - at this point you may want to adjust
      >> "Slope" (only) in the "Wide graph" just enough to flatten the
      >> high end.
      >>
      >> As conditions change (noisy vs. quiet band), you may want to
      >> touch up the transceiver output level or the interface input
      >> level slightly to keep the WSJT-X main audio level below 40 dB
      >> between xx:48 and xx:60. If signals are very strong you may
      >> need to turn off the receiver preamp, turn on an attenuator or
      >> back off the RF gain to prevent overloading the sound card.
      >>
      >> Note: If your transceiver does not have an adjustable output level
      >> and your interface does not have an adjustable input level, it may
      >> be necessary to substitute Windows' attenuator (Sound control
      >> panel | Recording Devices | <sound card being used> | Line | Level)
      >> for the adjustment in step 5.
      >>
      >> The goal of this process is to match the noise floor of the sound
      >> card to the zero signal level of WSJT-X (or *any other* digital
      >> package) and set the transceiver's zero signal level roughly 20
      >> dB above the sound card noise floor while not introducing any more
      >> gain than necessary so the sound card's analog to digital converter
      >> will not clip at maximum signal levels.
      >>
      >> 73,
      >>
      >> ... Joe, W4TV
      >>
      >
      >
    • Dave 'Doc' Corio
      Joe, First off, I can t thank you enough for the time you re taking for me. It s very enlightening and informative, and I appreciate it! However, I m not sure
      Message 2 of 8 , Aug 30, 2013
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        Joe, First off, I can't thank you enough for the time you're taking for me. It's very enlightening and informative, and I appreciate it!

        However, I'm not sure I've explained my issue in enough detail.

        I have no problem decoding in a general sense. For example, on a busy 20M JT9 band segment, if there are 12 stations all transmitting at once, chances are excellent that I'll decode every one of them - even down to levels of -25, sometimes even -28 dB.

        It's only when I engage a station in QSO that I see a problem. It works either of two ways:

        1. Station calls CQ
            I answer the CQ
            He replies to my call and he is not decoded

        or

        2. I call CQ
            Station responds to my CQ and is not decoded

        It's almost always that first transmission from the other station after I have transmitted that is not decoded.

        What really makes it difficult to diagnose is the fact that while his signal was not decoded, every other signal on the waterfall IS decoded!

        While it doesn't happen every time, I would guess that it occurs around 60 to 65 % of the time. It is more prevalent on the higher bands (30 thru 10M) and not nearly as much on the lower bands (160 thru 40M).

        I have recorded these using the WSJT-X audio recorder, and when played back, the same thing happens. Other stations decode just fine, but the one I'm in QSO with loses that first decode. Almost always, the rest of the QSO is fine, and unless I'm working a very weak station, the rest of his transmissions decode fine.

        I have to conclude, that while you may very well be right about the sound card in the SignaLink being quite noisy, that it is very unlikely that this would affect only one signal out of many on a waterfall - or that the only one it would affect would happen to be the one I'm trying to work at that moment, repeatedly.

        This problem has been going on for months, and is not limited to WSJT-X. It also happened with previous versions of WSJT as well as JT65-HF. However, I have had no problems with any other digital software such as DXLabs, MultiPSK, MMSSTV, EasyPal, and so on. It's only JT65 and JT-9 that seem to have an issue.

        Tnx es 73
        Doc
        KB3MOW

        On 8/29/2013 11:50 PM, Joe Subich, W4TV wrote:
         


        > The SignaLink USB, at least with Windows 7 does not have a "line"
        > input - only "microphone".

        "microphone" vs. "Line" is only a matter of the USB CODEC used -
        one would assume the hardware designer chose the appropriate
        input voltage level (and internal gain settings in the CODEC)
        for the device being used.

        > The first thing I noticed was that to bring the audio level from the
        > SignaLink (step 7) up to 20 or 25 dB I had to turn it all the way up.
        > May very well be due to the fact that I turned the Windows input from
        > 100% down to 65%.

        Then increase the Windows input. In theory increasing the input on
        the sound card driver would make it easier to overdrive the CODEC but
        perhaps your device is gain limited (or the transceiver is output
        limited).

        > Does the position of the cursor in the waterfall have any bearing on
        > what is decoded?


      • Joe Subich, W4TV
        ... No, you have made your issue painfully clear to all who read these lists. ... I don t know that I have ever seen either of those two scenarios. I suspect
        Message 3 of 8 , Aug 30, 2013
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          > However, I'm not sure I've explained my issue in enough detail.

          No, you have made your issue painfully clear to all who read these
          lists.

          > It's almost always that first transmission from the other station
          > _after I have transmitted_ that is not decoded.
          >
          > What really makes it difficult to diagnose is the fact that while
          > his signal was not decoded, every other signal on the waterfall IS
          > decoded!

          I don't know that I have ever seen either of those two scenarios. I
          suspect that only K1JT or one of the other volunteers in the developers
          group know if/how the initial quick on frequency decode differs from
          the broader secondary decode.

          > I have recorded these using the WSJT-X audio recorder, and when
          > played back, the same thing happens. Other stations decode just fine,
          > but the one I'm in QSO with loses that first decode.

          I would suggest sending those wave files to K1JT or one of the team
          and let them see if they can see what might be going on. They were
          able to determine the cause of the initial decoding issue in v 1.2
          by analyzing some of my wave files.

          > This problem has been going on for months, and is not limited to
          > WSJT-X. It also happened with previous versions of WSJT as well as
          > JT65-HF.

          That it happens with JT65-HF would tend to point to a hardware issue
          (sound card or computer) and not a software as the JT65-HF decoder
          is a separate development (different code) than WSJT or WSJT-X.
          Similarly, that it also occurs with JT9 would indicate an issue in
          the audio samples, not in the software. That it does not occur with
          non JT modes does not give the hardware a pass due to the differences
          between the JT modes and typical PSK modes.

          Causes could range from improper configuration of the sound card's
          hardware (default) sample rate to high priority process in the computer
          that runs at (or close to) xx:48 and disturbs the first decoding pass
          or even noise issues in the sound card at your working frequency.

          73,

          ... Joe, W4TV


          On 8/30/2013 6:45 AM, Dave 'Doc' Corio wrote:
          > Joe, First off, I can't thank you enough for the time you're taking for
          > me. It's very enlightening and informative, and I appreciate it!
          >
          > However, I'm not sure I've explained my issue in enough detail.
          >
          > I have no problem decoding in a general sense. For example, on a busy
          > 20M JT9 band segment, if there are 12 stations all transmitting at once,
          > chances are excellent that I'll decode every one of them - even down to
          > levels of -25, sometimes even -28 dB.
          >
          > It's only when I engage a station in QSO that I see a problem. It works
          > either of two ways:
          >
          > 1. Station calls CQ
          > I answer the CQ
          > He replies to my call and he is not decoded
          >
          > or
          >
          > 2. I call CQ
          > Station responds to my CQ and is not decoded
          >
          > It's almost always that first transmission from the other station _after
          > I have transmitted_ that is not decoded.
          >
          > What really makes it difficult to diagnose is the fact that while his
          > signal was not decoded, every other signal on the waterfall IS decoded!
          >
          > While it doesn't happen every time, I would guess that it occurs around
          > 60 to 65 % of the time. It is more prevalent on the higher bands (30
          > thru 10M) and not nearly as much on the lower bands (160 thru 40M).
          >
          > I have recorded these using the WSJT-X audio recorder, and when played
          > back, the same thing happens. Other stations decode just fine, but the
          > one I'm in QSO with loses that first decode. Almost always, the rest of
          > the QSO is fine, and unless I'm working a very weak station, the rest of
          > his transmissions decode fine.
          >
          > I have to conclude, that while you may very well be right about the
          > sound card in the SignaLink being quite noisy, that it is very unlikely
          > that this would affect only one signal out of many on a waterfall - or
          > that the only one it would affect would happen to be the one I'm trying
          > to work at that moment, repeatedly.
          >
          > This problem has been going on for months, and is not limited to WSJT-X.
          > It also happened with previous versions of WSJT as well as JT65-HF.
          > However, I have had no problems with any other digital software such as
          > DXLabs, MultiPSK, MMSSTV, EasyPal, and so on. It's only JT65 and JT-9
          > that seem to have an issue.
          >
          > Tnx es 73
          > Doc
          > KB3MOW
          >
          > On 8/29/2013 11:50 PM, Joe Subich, W4TV wrote:
          >>
          >>
          >> > The SignaLink USB, at least with Windows 7 does not have a "line"
          >> > input - only "microphone".
          >>
          >> "microphone" vs. "Line" is only a matter of the USB CODEC used -
          >> one would assume the hardware designer chose the appropriate
          >> input voltage level (and internal gain settings in the CODEC)
          >> for the device being used.
          >>
          >> > The first thing I noticed was that to bring the audio level from the
          >> > SignaLink (step 7) up to 20 or 25 dB I had to turn it all the way up.
          >> > May very well be due to the fact that I turned the Windows input from
          >> > 100% down to 65%.
          >>
          >> Then increase the Windows input. In theory increasing the input on
          >> the sound card driver would make it easier to overdrive the CODEC but
          >> perhaps your device is gain limited (or the transceiver is output
          >> limited).
          >>
          >> > Does the position of the cursor in the waterfall have any bearing on
          >> > what is decoded?
          >>
          >
          >
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