DATV -Express tx software and PTT

  • Hi,

    any idea to get a PTT output while the PTT button on DATV-Express tx software is pushed? Maybe via COM port?

    It is necessary to release the PA only a few ms after pressing the PTT button to prevent incomplete transmissions. (as we can see on the BATC WB monitor ....) Manually switching the PTT of the PA is no longer up to date ... ;)

    73´s de Robert

  • If you read the documentation for the DATV Express there is a signal placed on an IO line - you can set it up in the software for one of 4 PTT outputs. This will need an interface (transistor) to switch anything serious and probably isolation is needed - e.g. use a relay or opto-isolator.

    With the Lime or Pluto there is no IO line. However, for DATV the carrier is always there so perhaps you can simply detect the RF? This will need sequencing of the PA supply but putting 0 dBm into the PA with it's power off is probably safe.


  • Mike, sure, I read the documentation and had the described problem with Lime and Pluto.

    I'm not a fan of VOX circuits, especially as the Lime's and Plutos send a lot more uncontrolled when switching modes.

    For me, a clean solution would be a software link with the PTT button, which could trigger adjustable time delay to a COM port .... Unfortunately, it does not exist yet ...

    It remains only the solution proposed by you until someone adds the program code ...


  • Hi Robert,

    I don't think that is entirely true. I believe there is an interface to DATV Express that would allow you to set it to TX with some other software. This would mean writing a simple application to make the right calls. However, I can't find the documentation on this but it may be in the BATC forum archives.

    There is an alternative to DATV express for generating DATV on a PC using FFMPEG and Gnuradio. Adding Com PTT would be relatively easy. There is also the option for the Pluto of using RTMP.