A local FM station stopped transmitting their hd signal for several
weeks and then, all of a sudden, the digital signal appeared and the
analog was gone! As far as I can tell the usual un-modulated FM
carrier was completely missing and signal strength went to zero but
the modulated hd signal was there.

The interesting thing about all this was that the SonyXDR-S3HD
completely ignored the hd signal in hd scan mode. You had to manually
tune the radio to the correct frequency so that the radio to could
detect the hd component and produce a audible signal. (It also sounded
like crap).

All this tells me is that probably every HD radio in existence, will
not work correctly if/when hd becomes the norm.

Bottom line – There are so many unresolved issues concerning hd radio.
So many glitches and bugs not to mention the fact that no one is
listening and no one wants it ---- What’s the point?