Boston Globe Item on WERS LMA Proposal

Scott Fybush
Tue Apr 11 08:58:12 EDT 2006

> Interesting that technically,
> FM stations have been able for more than 30 years to broadcast mutiple
> (analog) audio streams. When HD Radio came along, some bright person must
> have said, "Wait a minute... This turkey ain't gonna fly--but if we can
> market it as enabling many new program sources, it'll seem to the public
> like... like... satellite radio... that's it, satellite radio without the
> monthly subscription fees." And so it must have been that HD subchannels
> were born. Known as turning a sow's ear into, umm, a sow's ear.

There's a real difference in quality between analog SCA and FM HD
subchannels, though. Even on the best of receivers, analog SCA sounds
worse than a passable AM, and that assumes a good signal level and an
absence of multipath. There's also a coverage limitation to an analog SCA

But if you have a receiver, and if it's properly engineered at the
station's end, FM HD subchannels can sound as good as the main channel
(indeed, if the station's doing two streams at 48k each, they're
essentially indistinguishable in quality.) If you can get the main HD, you
can get the subchannel, too. Advances in compression technology over the
next few years are likely to make HD3 and HD4 subchannels a reality, too.

It's not perfect, but it's better than the old analog SCA, anyway...

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