> I imagine that today they'd probably use something like Opus and a fountain code or similar, yes... But you can't expect everyone to replace their radio every 10-15 years ;)
Certainly not, which is why I believe DAB (no plus) is still floating around. And I'm not really suggesting that they made a bad choice.
I'm mostly pushing back on the notion that digital means all or nothing audio. If broadcast audio stays alive (which it may not) then I hope the next standard is opus, fountain codes, and QAM-64 or similar so we can stuff a bunch of bits into error correction while still having graceful degradation, better than analog, when the signal degrades.
I could be wrong, but I think DAB uses DQPSK (which can be thought of as a special version of QAM 4 if you squint a bit) and not anything like the higher QAM constellations because it's deliberately designed for mobile (road, train etc) where you don't have a steady signal, it can vary a lot with motion, so QAM 64 wouldn't really be possible.
Though I did a quick check and apparently DRM+ uses QAM-16, so perhaps my knowledge is far too out of date :S
LTE and 5g both use QAM 256 and higher. Wifi 7 can use QAM 4096 (though not a lot of motion there).