Fw: Letters To The Editor In Today's Globe

[Scott Fybush]

At 03:59 PM 1/15/2006, Dan Strassberg wrote:

>I think Bob was wrong. I believe that if a station uses only two channels,
>versus the three that Bob mentioned repeatedly, the second channel has the
>same bit rate as the main channel, but, in that case, both channels have
>only half the bit rate of the main channel of an FM that transmits only the
>main HD Radio channel. I can't recall the bit rates, but I think that the
>bit rate for an FM that transmits only the main HD channel is 128 kbps.

96 kbps, actually, which can be broken up in a variety of ways, at 
the station's discretion. Some stations are using 64 for the main and 
32 for the HD-1 subchannel. Others are using 48 and 48. It's also 
possible to do three streams, 48-24-24, and I know of at least one 
station that's doing that (WBOI 89.1 in Fort Wayne, Indiana.)

>If that's
>your conclusion, you'd be wrong because HD Radio's lossy-compression
>algorithms are more advanced than MP3's compression algorithms (which, IIRC,
>are not lossy). Although the point is subject to heated debate and the
>conclusions about audio quality are intimately related to the program
>content, some people say that 32 kbps in HD Radio produces audio quality
>that is comparable to that of a 128-kbps MP3 stream.

Both MP3 and the variant of AAC that's used in HD Radio are most 
definitely lossy. I've heard various configurations of the HD Radio 
AAC scheme, and in my experience, there's audible artifacting even in 
the full-channel 96 k mode. Once you're down to 32, for AM HD or an 
FM subchannel, I find the artifacting audibly objectionable. 
Ironically, the AAC encoder seems (at least to my ear) to work far 
better for music at low bitrates than it does for voice, thus 
yielding the irony that (again, at least to my ear) the talk formats 
that are most likely to show up on such low-bitrate subchannels work 
least well there.

(At the risk of veering somewhat off-topic, the most objectionable 
artifacting I've ever heard is on the extremely low-bitrate channels 
that XM uses to deliver its "local" traffic and weather services. 
I've heard estimates that those channels use as little as 8 kbps, and 
the result is that for some voices, especially female ones, they're 
quite literally unintelligible. I believe XM uses a similar AAC 
encoder to HD, unless I'm thinking of Sirius.)

>In a sense, though, this discussion is kind of a red herring. You don't need
>HD Radio to transmit FOUR programs on a (nominally) 200-kHz-wide FM channel.
>Analog FM allows for a main channel and three subcarriers. The subcarriers,
>which are frequency modulated onto the main carrier, are themselves,
>amplitude modulated, and none has the 15-kHz bandwidth of the main channel.
>As I understand it, current regulations make it illegal to sell to the
>general public in the US FM receivers that decode the analog subcarriers.
>These are reserved for subscription services, such as background music.

The use of subcarriers for background music is essentially dead now, 
with satellite-based services having largely taken over that market. 
The primary uses now are for niche ethnic programming (with the 
program providers often selling fixed-tuned receivers to potential 
listeners), radio reading services, and for data paging. The audio 
quality of these subcarriers is uniformly hideous.

There's another new technology called "Digital Radio Extra," or DRE, 
which uses the subcarrier bandwidth to transmit digital carriers. 
It's attracted a lot of interest from broadcasters who see it as a 
logical replacement for today's analog subcarriers. It's actually 
compatible with "HD Radio" IBOC (by virtue of the fact that it's 
really IBAC), and it sounds MUCH better than analog SCA. The big 
hangup here, as with HD Radio, is receiver availability. It's not yet 
clear that the specialized receivers are going to be available in 
quantity quickly enough to satisfy demand. If you're running a 
reading service, for instance, you need to swap out ALL your 
receivers in the field at once to successfully convert from analog 
SCA to DRE. I believe the reading service we run at WXXI in 
Rochester, for instance, has somewhere more than 10,000 receivers in 
the field. That won't be an easy swap when the time comes.

>iBiquity et al have decided to make the subcarriers available in radios sold
>to the general public, thus providing the potential of additional revenue
>streams from one FM license. If the set makers can get the cost, size and
>power-conumption of HD Radio receivers down to reasonable levels, this may
>become the key feature of the system. However, the idea of the broadcasters
>conspiring to allocate different formats to different companies sounds
>illegal to me because it appears to be in restraint of trade. And given the
>competitiveness of broadcasters in just about any multi-station market, the
>idea seems to define the word "unworkable." Haven't the clowns who set up
>the consortium idea ever heard of format flips? Can you imagine any
>broadcaster agreeing to change a format only if all competitors in the
>market approve of the switch? That has to be the biggest laugh of this
>still-young millennium

While there are many questions that deserve to be raised about the 
plan, I take serious issue with calling those behind it "clowns." I 
know, and respect, many of the players involved, in particular Clear 
Channel's engineering chief, Steve Davis, and I know that all parties 
have had the legal eagles working closely with them to stay on the 
right side of the Justice Department in all of this.

It's my understanding, based on what's been said publicly by Davis 
and others involved in the consortium, that they won't be 
"allocating" different formats to different companies. The concept is 
to coordinate the choices being made by each of the participating 
clusters in any given market to make as many distinct format choices 
available to consumers as quickly as possible. I assume the idea is 
to make sure that New York, for instance, doesn't end up with four 
groups all trying to launch country formats on their HD subchannels. 
There's probably room for ONE country station in NYC. There's not 
room for four. (I have no idea what sort of mechanisms are in place 
to decide which of the broadcasters would end up with the format.) In 
any event, it's my understanding that there's no "veto" power that 
any one group would have over any other group's decision to change 
formats later on.

It's also my understanding that this is a short-term effort, with a 
defined sunset date after which everyone will compete freely. While 
the format-coordination part of the plan has received most of the 
media attention, the real thrust of this coalition is to put some 
industry muscle behind promoting HD Radio and getting radios on store 
shelves and into dashboards. One might argue that it comes about 
three years later than it should, but the fact that it's being done 
at all seems to me to be a good thing, and if the industry can offer 
consumers a menu of choices that they wouldn't otherwise have on the 
dial (country or oldies in NYC, classical in Boston, and so on), it 
may be the last hope the technology has of achieving liftoff.

s