A quiet month for me, as I spent much of August hiking the Larapinta trail, a rugged 230 km walk in the middle of Australia.

However I did have some time for a little FreeDV work. I spent some time finalising an upcoming QST article on RADE, working with the good people at the ARRL.

Most of the time was spent tracking down a subtle issue thrown up by verification procedure – the “loss” metric of the C version of RADE V2 was found to be sensitive to the timing offset (thanks Mooneer for finding this one). Turns out this was an AGC algorithm error, which I have been working on correcting, testing, and documenting. I’ve had this experience before – when e.g. when manually porting between Octave and C for previous FreeDV modes.

These days with agentic coding the port is (e.g from Python to C) quite fast (~ 1 day compared to months doing it manually) – but for these subtle bugs a human guiding the AI was definitely required to track down the root cause. Claude, however, deserves the credit for suggesting we try running without AGC which finally trapped the issue.