WCBS Newsradio 880 in HD, FM that is!

Aaron Read readaaron@friedbagels.com
Fri Oct 3 12:02:05 EDT 2008

Eli Polonsky wrote:
 > ... if my home HD tuner loses a subchannel, it falls back to the 
stations main
 > analog channel, just like when it loses the HD-1.
Odd decision on the part of the architects.  I'd prefer silence.
Imagine if an AM radio lost a signal and just automatically scanned to
the next higher signal on the band?

It wasn't a decision.  The original design for HD Radio had no provision 
for multicasting.  It was just going to be a digital simulcast of the 
analog signal and that was it.  Hence, the "blend back" style, where the 
receiver blends back to analog whenever the digital signal is lost; the 
content on both was the same...so while there'd be a noticeable drop in 
audio quality, it wouldn't be all that jarring.

NPR realized the tremendous waste of potential and, in conjunction with 
Kenwood, essentially invented "Tomorrow Radio" which eventually became 
known as "multicasting".  NAB and iBiquity HATED it at first - it had 
the potential to divide the advertising pie even further - but 
eventually the logic overwhelmed the profit margin...a rare time that's 

Unfortunately, because Tomorrow Radio was created fairly late in the 
game, there wasn't really a plan for what happens when the HD signal 
gets too weak to maintain a HD-n stream.  And since it's digital...as 
in, either there or not...the listener has little clue the signal is 
getting marginal until suddenly the multicast channel keeps muting 
repeatedly.  I listen to multicasts around here quite a bit, and I admit 
it can be rather maddening when I get out on the fringe.

Most radios will stay with a muted multicast channel for at least 10 to 
20 seconds before giving up and going back to analog.  Often it'll last 
a few minutes if there's HD signal there, but not enough to fill the 
buffer and start playing audio.

Aaron Read		    |  Finger Lakes Public Radio
readaaron@friedbagels.com   |  General Manager (WEOS & WHWS-LP)
Geneva, NY 14456	    |  www.weos.org / www.whws.fm

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