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Problem with tx delay (JT65-HF, VAC)

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  • neomag_magneo
    Dear group, I have been playing with my Softrock based SDR rig by installing the PowerSDR-IQ V1.12.20 software which has LPT output for Si570 control and PTT.
    Message 1 of 8 , Jan 10, 2014
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      Dear group,

      I have been playing with my Softrock based SDR rig by installing the PowerSDR-IQ V1.12.20 software which has LPT output for Si570 control and PTT. Previously I have been using the PowerSDR-sr40 with little problems but it did lack the smooth tuning for Si570. One major problem, however, has arised, related to the JT65-HF software ! This item has been discussed here b4 but I could not come up with any striaghtforward solution from what I managed to read.

      When transmitting with PowerSDR the starting point for JT65-HF tx drifts from 0 up to 5 s during the course of time, say 10 minutes or so. I have tried to change the latency time in the PowerSDR setup for VAC (V4.10 right now) and when below 50 (ms) the tx delay goes down to zero. However, similar delay is introduced to rx signals. When playing with various parameters (latency, buffer size, sampling rate) I have also fould that their setup is much more critical than what I exprenced with PowerSDR-sr40 earlier.

      My setup:

      PowerSDR-IQ V1.12.20
      VAC 4.10
      JT65-HF V 1.0.9.3

      Win XP SP3

      This exercise has been somewhat frustrating, in particular when I assume, that a solution exists somewhere. If not, I would be very happy to know, if any better versions of my software does exist and could be applied. I should emphasize, though, that currently I am more or less stuck with LPT control.

      73 de Heikki (OH2LZI)

       
    • sv1eia
      What are the specs of your PC?
      Message 2 of 8 , Jan 10, 2014
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        What are the specs of your PC?
      • neomag_magneo
        Win XP professional SP3 Pentium D CPU 2.8 GHz 1.5GB RAM Quite modest, but adequate for many applications BR Heikki (OH2LZI)
        Message 3 of 8 , Jan 11, 2014
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          Win XP professional SP3


          Pentium D CPU 2.8 GHz

          1.5GB RAM


          Quite modest, but adequate for many applications


          BR


          Heikki (OH2LZI)

        • sv1eia
          VAC is introducing time leakage specially when a system is not fast enough. As time passes, it accumulates audio time in its buffers, its cleared with a
          Message 4 of 8 , Jan 11, 2014
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            VAC is introducing 'time leakage' specially when a system is not fast enough.
            As time passes, it accumulates audio time in its buffers, its cleared with a Stop/Start button press.
            That is more evident in older versions, the newer (1.19) perform better in that regard.
          • neomag_magneo
            Dear Christos, Mni tks for the explanation, this is what I was suspecting after all... One question still: Are you referring to the restart-button in the VAC
            Message 5 of 8 , Jan 11, 2014
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              Dear Christos,


              Mni tks for the explanation, this is what I was suspecting after all...


              One question still: Are you referring to the restart-button in the VAC control panel or something else?? This button will not work unless You stop all the software using VAC .


              BR


              Heikki (OH2LZI)

            • sv1eia
              The main Start/Stop application button, only this does a buffer reset.
              Message 6 of 8 , Jan 11, 2014
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                The main Start/Stop application button, only this does a buffer reset.
              • OM0AAO Viliam
                Hi, I was dealing with VAC on the T2370 Dual CPU 3GB RAM WinXP SP3 (PowerSDR, VAC, N1MM RTTY). When started latency was not stable 2-6 seconds! Trying to play
                Message 7 of 8 , Jan 11, 2014
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                  Hi,



                  I was dealing with VAC on the T2370 Dual CPU 3GB RAM WinXP SP3 (PowerSDR, VAC, N1MM RTTY). When started latency was not stable 2-6 seconds! Trying to play with VAC setup "ms per Int" and other improved it to the 0,7 seconds. I know that it could be much better! On my 2nd PC I obtain much better results...



                  73'Viliam, OM0AAO / OM0A

                  administrator www.cq.sk

                • skarbows
                  I quit using VAC sometime ago. I now use VB-Audio-Cable-A and VB-Audio-Cable-B from VB-Audio It s donation-ware and seems to work far better for me than VAC.
                  Message 8 of 8 , Jan 12, 2014
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                    I quit using VAC sometime ago.  I now use VB-Audio-Cable-A and VB-Audio-Cable-B from VB-Audio  It's donation-ware and seems to work far better for me than VAC.  VB-Audio has some other neat software too.
                     
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