gr-display is a small qt based addon for gnuradio.

It contains three components:

• show_image : display png images.

• show_text : display ascii characters as text in a qt window.

• display_text_msg : display a message containing text, or a message of type u8vector

Messages of type u8vector are provided by gr_satellites decoder, for example.

I use show_image to receive and display some weather- satellite pictures with the funcube dongle and gnuradio.

You'll find them in:

Custom

    Display

1. Dependencies:

   • gnuradio ( >= 3.10) with pybind11

   • gr-qtgui

   • qt5

2. Installation

   Get the latest code from https://github.com/dl1ksv/gr-display

   The build process is cmake based. So change to the code directory.

   There

   $mkdir build

   $cd build

   $cmake -DCMAKE_INSTALL_PREFIX= < where gnuradio is installed > ../

   $make

   $sudo make install

   After that you'll find in grc in DL1KSV / Display

   • Display a text message
   • PNG Image sink
   • Text sink.

++++ If you are unsure about where gnuradio is installed run

 gnuradio-config-info --prefix


 **Hint:**  
 You can install gr-display to an other directory than gnuradio. But then you have to add
 the location of your python modules to the PYTHONPATH environment variable and add the location of
 the lib to the LD_LIBRARY_PATH environment variable.

 To see the newly created blocks in grc you have to set the local_blocks_path entry in ~/.gnuradio/config.conf.
 Example: If you choose /usr/local/oot as installation directory, you have to set 
 local_blocks_path = /usr/local/oot/share/gnuradio/grc/blocks

3. Changes

   Two additional parameters where introduced:

   • splitlength
     If splitlength > 0 , a linebreak is inserted if the linelength exceeds splitlength characters.
   • maxlines
     Restricts the display height to maxlines rows

These parameters where introduced to avoid display problems on heavy load and very long lines.

An autofocus option was added, so you always see new text, if this option is enabled.

4. To do

   Perhaps do some simple image processing like rotating before saving.