[opendtv] Re: Fwd: DAB+ in the USA
- From: Albert Manfredi <albert.e.manfredi@xxxxxxxxxx>
- To: <opendtv@xxxxxxxxxxxxx>
- Date: Tue, 1 Apr 2008 21:25:35 -0400
Barry Wilkins wrote:
> [IBOC] may not be any more attractive to the broadcasters,
> perhaps unattractive. But if, as I have heard, IBOC is causing
> a lot of noise interference and there has not been the mass
> adoption expected perhaps DAB+ will succeed. It is spectrum
> efficient for the amount of channels and data rate compared
> to DAB (Eureka 147) but obviously IBOC was a "having your
> cake and eating it" scenario. The reality though may be that
> perhaps the cake was not as yummy as expected.
Chuckles.
Actually, this is an interesting topic. I don't believe in any "best of all
worlds" characterizations. They're usually flawed. So HD Radio does ease the
transition, and it also works in the AM band by the way, so that seems like an
advantage over DAB+. (Of course, DRM provides the AM digital in Europe.) But
this ease of transition isn't for free.
In the FM band, with HD Radio you get 100 to 150 Kb/s in hybrid mode (max,
depending what source you read), or 300 Kb/s in all digital. But even in hybrid
mode, I get two music multicasts or three voice multicasts that sound quite
good, on a decent stereo system I mean. Not a little table radio. I have no
issues with sound quality.
The price paid for this, as far as I can tell, is primarily that in hybrid
mode, the digital signal is severely power limited. And in the FM band, in
hybrid mode, the signal is also bit rate limited, compared to what it could be
in all-digital mode.
The effect in the AM band, when HD Radio transitions to digital, is stunning.
Much more stunning than in the FM band. Even though in this hybrid mode, the
bit rate is under 40 Kb/s. In an all digital AM case, the bandwidth is reduced
from 30 KHz to 10 or 20 KHz, so actually the bit rate compared with hybrid mode
does not change so much.
As to purported noise to analog radio users? I have not experienced that at all
in analog FM radios, although it makes sense that a mistuned AM radio would
hear the digital sidebands of the digital signal. At reduced power. (I never
listen to AM, so ...)
HD Radio uses some version of HE-AAC codec, which is similar or the same as
DAB+'s AAC+, and also the same as DRM. So in that sense, no big diff.
The cost of the tuner, like my Sangean HDT-1, $200, is very comparable to
analog AM/FM hifi tuners of the past. You can buy cheaper stand-alone stuff.
So all in all, I don't see any overarching reason to favor HD Radio over DAB+,
or vv, except for the ease of transition business. And yes, HD Radio has
royalties associated with it, so that's probably a minus.
Bottom line is, this is just like DTT. If IBOC does *not* succeed in the US, my
take is that people either prefer to get stuck with a satellite radio bill, or
they are plenty happy with analog radio. It just doesn't make a lot of sense to
believe that people would flock to a DAB receiver *rather than* and HD Radio
receiver, to me anyway.
Bert
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