Hi @EliotBR , thanks for the follow up on this.
As the version of Qt Iām running is 5.12, I looked through the commit history checked out the commit 3a0cec3 (which should be the last commit prior to PingViewer being updated to 5.15). After installing some additional qt submodules, I was able to build and run the PingViewer on my RPi4, successfully interfacing it with my Ping360 sonar.
Will look out for the new build instructions and likely upgrade to Qt5.15 then! 