HD radio?

[Dan Strassberg]

On FM probably yes. But I'm skeptical about putting two independent digital
channels on one AM-band carrier. The bandwidth isn't even adequate for a
decent-sounding stereo signal. iBiquity manages to get a semi-OK stereo
signal onto AM by a) using substantially more bandwidth than analog AM does
and b) using lossy compression, which creates unpleasant artifacts for some
kinds of program material. The claims of the AM-band version sounding as
good as (analog) FM and the FM-band version sounding as good as a CD are
largely the product of the fertile minds of PR people.

Now, the extra bandwidth consumed by both the AM-band and FM-band versions
is mainly the result of building a compatible system--one that
works--however badly--with existing analog radios. An incompatible system
simply wouldn't have a chance in the marketplace. The advantages of digital
transmission just aren't great enough to motivate Americans to discard
nearly a billion radios and replace them with radios that cost (at least
initially) several hundred dollars each. However, compatibility requires
extra bandwidth because of the need to transmit both analog and digital
signals.

I don't think iBiquity's AM-band system has a chance despite its nominal
compatibility. The strongest proponents seem to be station owners who have
no technical understanding and who believe that HD Radio will be the
salvation of their licenses. These folks seem to believe that if they keep
smiling and talk up the advantages that iBiquity's press releases trumpet,
they can make fictiion into reality. The problem is that all the optimism in
the world can't repeal the laws of physics.

If there were no requirement for compatibility, however, a good AM-band
system could be built and the signals wouldn't have to use more bandwidth
than existing analog AM signals. In fact, a good digital AM-band system
exists. It's the European Digital Radio Mondiale system, which has never
been given a chance in the US. The official reason that DRM never got a
chance here is its incompatibility with existing radios. Although the
allegations of incompatibility are true--and nobody associated with DRM ever
said otherwise--politics supposedly played a role in DRM's never getting a
chance.

--
Dan Strassberg, dan.strassberg@att.net
eFax 707-215-6367

----- Original Message -----
From: "Bill O'Neill" <billo@shoreham.net>
To: "Joseph Pappalardo" <joepappalardo2001@yahoo.com>
Cc: <boston-radio-interest@rolinin.BostonRadio.org>
Sent: Saturday, January 22, 2005 5:07 PM
Subject: Re: HD radio?


> Joseph Pappalardo wrote:
>
> >As a result of our digital
> >architecture, enhanced services such as increased data capacity, surround
> >sound or other multi-casting solutions can be made available across this
> >unused bandwidth.
> >
> Could a "station" operate more than one "station" in their bandwidth,
> like going condo?
>
> Bill O'Neill