Yes, when I was with a friend in the US, I noticed how their radio kept flicking back between the analogue and digital signal when the signal got weak.
Maybe a better system than the DAB one we're using.
It's a bit of a joke how many DAB stations are mono- in 2019.
I'd like to see HD radio used alongside DAB or more likely DAB+, in years to come, it can be used on AM too. But the likelihood of that happening is absolute zero.
It's sub-carriers added to the primary FM or AM analogue carrier. You can't do that with DAB because the COFDM signal is 1700 separte carriers, and you can't have sidebands, different kettle of fish completely.
It works alongside the analogue signal rather like NICAM did on our analogue TV system, and as
observed if the signal reduces to an unacceptable level, the digital output is replaced by the analogue, (which is what happened to NICAM too on weak signals)
That wasn't quite what I meant, apologies for not making that clear.
I would like to see HD Radio used on the AM & FM wavebands, and DAB+ used on the current DAB band. You could use both technologies simultaneously, as they broadcast in different wavebands. FM is 87.5 to 108, whilst DAB is 176 to 212, so there's space to use both technologies. As I said, it has absolutely zero chance of happening, but I would like to see it.