Gang,
The current issue of "Pro Audio Review" is dedicated to "HD Radio."
Although not always called by this name, it's been coming for about 15
years. Now that digital satellite radio is making its initial splash
(IT'S THE CONTENT, STUPID), American broadcasters may reluctantly roll
out what is basically "mp3 radio." Sorry, but data-compressed digital
audio is just not going to be a step up in quality for terrestrial
broadcasters, IMNSHO.

But that's not even my beef. Frank Foti states that, upstream of the
new digital delivery orifice, "Care should be taken to avoid using heavy
dynamics processing such as high ratio limiting, clipping of any sort,
as well as radical EQ curves...." Oh. So the new HD radio is going to
wreak havoc on anything that's heavily compressed. Is that all?

Is there some law that I don't know about that compels people to come up
with the most useless new products and standards possible? Why
wouldn't any new compression algorithm take into account the LIKELY
SOURCE MATERIAL - heavily-compressed songs and commercials?!?

I spent 13 years in radio and still produce content for the medium. I'm
baffled. If the intent is to make everyone smash their Smashalizers,
I'll vote for that. Twice. But don't we have about 30 years of
highly-compressed back-catalog to somehow now "de-compress" to make it
work on this cool new digital radio thingy? Perhaps Mr. Foti is working
on an UnProcessor....?

Yours,
Dan Popp
Colors Audio

Dan Popp wrote:

Gang,
The current issue of "Pro Audio Review" is dedicated to "HD Radio."
Although not always called by this name, it's been coming for about 15
years. Now that digital satellite radio is making its initial splash
(IT'S THE CONTENT, STUPID), American broadcasters may reluctantly roll
out what is basically "mp3 radio." Sorry, but data-compressed digital
audio is just not going to be a step up in quality for terrestrial
broadcasters, IMNSHO.

But that's not even my beef. Frank Foti states that, upstream of the
new digital delivery orifice, "Care should be taken to avoid using heavy
dynamics processing such as high ratio limiting, clipping of any sort,
as well as radical EQ curves...." Oh. So the new HD radio is going to
wreak havoc on anything that's heavily compressed. Is that all?

Is there some law that I don't know about that compels people to come up
with the most useless new products and standards possible? Why
wouldn't any new compression algorithm take into account the LIKELY
SOURCE MATERIAL - heavily-compressed songs and commercials?!?

I spent 13 years in radio and still produce content for the medium. I'm
baffled. If the intent is to make everyone smash their Smashalizers,
I'll vote for that. Twice. But don't we have about 30 years of
highly-compressed back-catalog to somehow now "de-compress" to make it
work on this cool new digital radio thingy? Perhaps Mr. Foti is working
on an UnProcessor....?

Yours,
Dan Popp
Colors Audio

Dear Dan.

In the future, all music will sound like it's being played back on a
cellphone in a fringe area, placed inside an operating blender. This is
progress! especially since we all now know that lousy sounding FM was
inevitable.

--
Les Cargill

Dan Popp wrote in message ...


But that's not even my beef. Frank Foti states that, upstream of the
new digital delivery orifice, "Care should be taken to avoid using heavy
dynamics processing such as high ratio limiting, clipping of any sort,
as well as radical EQ curves...." Oh. So the new HD radio is going to
wreak havoc on anything that's heavily compressed. Is that all?


Actually, it's that Frank Foti is in the business of selling dynamics
processing equipment, & if the program material is already squashed he
won't be able to justify his product to end users (broadcasters).

In article , Dan Popp
wrote:


Is there some law that I don't know about that compels people to come up
with the most useless new products and standards possible? Why
wouldn't any new compression algorithm take into account the LIKELY
SOURCE MATERIAL - heavily-compressed songs and commercials?!?

Heavily-compressed songs and commercials sound like sh!t on the air now
but they generate great numbers in focus groups which seems to be far
more important to most broadcasters and their sponsors than loyal
listeners do.

--
Bob Olhsson Audio Mastery, Nashville TN 615.385.8051
Mastering, Audio for Picture, Mix Evaluation and Quality Control
http://www.hyperback.com/olhsson.html
Over 40 years making people sound better than they ever imagined!

G,
You should read the article, or visit the omniaaudio.com web site and read
the tech
publication. Mr. F repeatedly states that pre-compressed audio makes HD
Radio
sound *worse*... counter-intuitive as it may be to those of us who have been
intentionally over-processing audio for mp3s and other limited formats.

If you say that this doesn't sound like an mp3, I have no reason to
disbelieve
you. But please explain how that's possible, since the FM bitstream is a
whopping
96 kbps - far below the 320 kbps stereo .mp3s I send out now. And how can we
get
that superior radio compression technology for recorded files?

As for Buster's remarks above, I regret that my words could be read to imply
that
Mr. Foti was somehow responsible for this. As far as I know, he's just
trying to
make the best out of (what still appears to me to be) a very bad situation.

Multipath my butt. I'll trade that for 7-second latency and a reduction in
both
the power and freq. response of the analog signal any day. The analog AM
signal
has to be cut to 5kHz (!) to make this work. Yeah, how did we ever live
without
this?

Yours,
Dan Popp
Colors Audio



As far as quality comparison, I would use WMA as a good example. Generally, WMA
is perceived to be of equal quality to MP3 encoded at twice the rate (low to
medium rates, IIRC). For personal use, WMA at 128 to 160 kb/s will satisfy me,
but typical, fixed rate MP3 can be marginal in that region. (Some of the newer
versions of MP3 are probably better, haven't tried those enhanced versions.)
The HD Radio codec is significantly newer than any of the commercially
available versions of MP3 and WMA. My own assessment is that it is a bit more
efficient than WMA for the same quality. 96 kb/s stereo easily sounds as good
as the best stationary analog FM. I agree with many people who say that analog
FM can sound extremely good -- if stationary and in a low MP area, with the
mimimal audio processing required to meet modulation restrictions.

Multipath is a tricky issue. In the absence of side-by-side comparos, most FM
radio listeners perceptually filter out MP effects. When faced with direct
comparison with source (or HD Radio), many are amazed at the number of MP
artifacts present in mobile FM reception -- especially in speech and
classical/jazz music programming. I've actully heard more than one person state
that the comparisions "ruined FM radio for them." But admittedly, these
comparos were with critical (to MP) program material and light audio processing
of the music.

Also, there are at least two very effective ways the current broadcast/receiver
technologies minimize MP effects:

*Many receivers use variable audio bandwidth filtering (cutting highs in severe
MP and interference) and adaptive stereo-to-mono demux blending and hybrids
thereof. Note the "stereo" indicator always remains "on," as this is really a
stereo pilot lock indicator ... unfortunately, most listeners are satisfied
just knowing that stereo light is lit. Limiting stereo separation at the
broadcast end helps, as well.

*Heavy audio processing of source audio, combined with extensive use of
voice-overs (never any plain speech) is one of the most effective ways to
combat MP. The added benefit to the broadcaster is that this is the same type
fo processing most love to use in making their stations sound loud. This method
works very well for rock, pop, country and the like. It's almost totally
ineffective for speech (news, talk-radio) and high quality music (classical).

These methods, while effective, definitely reduce the overall quality of the
FM. My point in all this is that FM-band HD Radio transmission requires none of
this to hide MP. It's a robustness advantage that can lead to an audio quality
improvement. Will it matter for the highly-processed top 40 (okay, top 5)
station? Nope. But some of us have hopes for speech and arts programming.

MP is predominantly FM issue. AM is a whole different situation, dominated by
the interference and noise associated with linear demodulation. My comments
don't apply to AM.

As far as HD Radio codec availabilty for recording -- got me on that. I'm sure
if money can be made, it'll happen. Have to contact iBiquity...

-G
-Greg

****************************************
strike out 3-times to reply by email

Bob,
I don't disagree with you that over-compression is a terrible problem. But
the point is that (apparently, judging from what I've read so far) compressed
stuff sounds *worse* on Half Digital Radio. If you suggest pulling back on
the compression, fine... but we're still dealing with the noisy playback
environment of a moving car... we're still dealing with human beings
programming and engineering these stations, and human nature is not going to
change just because Greg wants it to. My question still stands; Why take
away one of our tools (even if the tool is often abused) to make
data-compressed audio sound less horrible?

Yours,
Dan Popp
Colors Audio
USA

Bob Olhsson wrote:

In article , Dan Popp
wrote:


Is there some law that I don't know about that compels people to come up
with the most useless new products and standards possible? Why
wouldn't any new compression algorithm take into account the LIKELY
SOURCE MATERIAL - heavily-compressed songs and commercials?!?

Heavily-compressed songs and commercials sound like sh!t on the air now
but they generate great numbers in focus groups which seems to be far
more important to most broadcasters and their sponsors than loyal
listeners do.

--
Bob Olhsson Audio Mastery, Nashville TN 615.385.8051
Mastering, Audio for Picture, Mix Evaluation and Quality Control
http://www.hyperback.com/olhsson.html
Over 40 years making people sound better than they ever imagined!

I'm really behind the times. I never even heard of "HD Radio" until
the latest issue of Pro Audio Review worked its way up to the top of
the stack in the tile reading room. I had to read a bit into the
issue before I even figured out that HD stood for "high definition."

My almost completely uninformed but gut feeling about this is that
it's presently a mix of two relatively incompatible technologies that
are fighting each other because of bandwidth limitations. When we have
enough bandwidth for true high definition broadcast, that will be when
I'm ready to accept it. Until then, I might play around with the
present day toys when they get cheap enough.

I couldn't even figure out what an "HD radio receiver" looks like. Is
there a means of transmitting this over the air, picked up by a normal
receiver with some sort of adapter, or is it strictly over the
Internet, at least for now? One of the articles mentioned a mobile
receiver "as big as a bus" which doesn't sound like it's ready for the
Walkman crowd yet.



--
I'm really Mike Rivers - )

In article znr1064489974k@trad, Mike Rivers wrote:

My almost completely uninformed but gut feeling about this is that
it's presently a mix of two relatively incompatible technologies that
are fighting each other because of bandwidth limitations. When we have
enough bandwidth for true high definition broadcast, that will be when
I'm ready to accept it. Until then, I might play around with the
present day toys when they get cheap enough.

It's a lot more than just two.

1. Satellite services like XM and Sirius, broadcasting many channels
uplinked from a single location to a satellite.

2. FM IBOC (In Band On Channel), where existing FM stations use subcarriers
or additional digital carriers to carry digital channels from terrestrial
stations.

3. AM IBOC which has a very different configuration, with godawful low quality
digital audio shoehorned between channels. This also kills any possibility
of the main analogue signal being high quality and it does not survive skip
well at all.

4. Out of band terrestrial systems. In Europe, they are using an L-Band system
called Eureka which is very popular. This is not being used in the US at
all due to frequency allocation issues, but it's probably going to get
adopted by everyone else in the world.

I couldn't even figure out what an "HD radio receiver" looks like. Is
there a means of transmitting this over the air, picked up by a normal
receiver with some sort of adapter, or is it strictly over the
Internet, at least for now? One of the articles mentioned a mobile
receiver "as big as a bus" which doesn't sound like it's ready for the
Walkman crowd yet.

XM and Sirius systems are available at your local truckstop, built into
boxes that replace existing auto radios, or in outboard boxes that will feed
line audio into an auto radio. FM IBOC receivers are available from Kenwood
sort of.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

"Scott Dorsey" wrote in message


In article znr1064489974k@trad, Mike Rivers
wrote:

My almost completely uninformed but gut feeling about this is that
it's presently a mix of two relatively incompatible technologies that
are fighting each other because of bandwidth limitations. When we
have enough bandwidth for true high definition broadcast, that will
be when I'm ready to accept it. Until then, I might play around with
the present day toys when they get cheap enough.

It's a lot more than just two.

1. Satellite services like XM and Sirius, broadcasting many channels
uplinked from a single location to a satellite.

Calling this perceptually-coded stuff "High Definition" has to be some kind
of flight of fantasy or fancy marketing.

2. FM IBOC (In Band On Channel), where existing FM stations use
subcarriers or additional digital carriers to carry digital
channels from terrestrial stations.

To be anything like hifi, this also needs to be perceptually coded because
otherwise the real resolution and bandwidth aren't there. See my comment
about item 1.

3. AM IBOC which has a very different configuration, with godawful
low quality digital audio shoehorned between channels. This also
kills any possibility of the main analogue signal being high
quality and it does not survive skip well at all.

Yes, even bigger jokes as true HD than 1 & 2

4. Out of band terrestrial systems. In Europe, they are using an
L-Band system called Eureka which is very popular. This is not
being used in the US at all due to frequency allocation issues,
but it's probably going to get adopted by everyone else in the
world.

The full name of this appears to be Eureka-147 or DAB

http://www.worlddab.org/public_docum...ka_leaflet.pdf

More perceptual coding.

I couldn't even figure out what an "HD radio receiver" looks like. Is
there a means of transmitting this over the air, picked up by a
normal receiver with some sort of adapter, or is it strictly over the
Internet, at least for now? One of the articles mentioned a mobile
receiver "as big as a bus" which doesn't sound like it's ready for
the Walkman crowd yet.

XM and Sirius systems are available at your local truckstop, built
into boxes that replace existing auto radios, or in outboard boxes
that will feed line audio into an auto radio.

Consumer appliance stores in my area also have this hardware. This might
have something to do with Detroit having the HQs of two major investors in
these service providers. XM seems to be outgrowing Sirius, but Sirius got a
late start because Lucent was their hardware source and they dropped the
ball, big time.

http://www.broadcast.net/pipermail/r...ry/170845.html

FM IBOC receivers are available from Kenwood sort of.

See page 4 of http://www.worlddab.org/public_docum...ka_leaflet.pdf

I've heard it discussed on UK audio forums. It's perceptually coded so it is
not a sonically perfect solution at this point in time.

Mike Rivers wrote:

I had to read a bit into the
issue before I even figured out that HD stood for "high definition."

I like my explanation better: "Half Digital."

Is
there a means of transmitting this over the air,

Mike,
The other replies were spot-on, I think. The deeper you dig into this
technology, the worse it gets. Remember that they've had a dozen years or
more (since the Americans decided that they wanted to keep their current
spectrum allocation at all costs and abandon the Eureka system the rest of
the world is using) to perfect this. There is a 3-second buffer that has
to be filled in your car radio before the digital signal starts to play.
In the interim, it plays the analog signal. Of course, if the digital
signal is lost, the receiver defaults back to analog as well... which
should make one wonder: if the digital signal is so superior, why is the
analog signal still useable when the digital signal is not?

Yours,
Dan Popp
Colors Audio
USA

In article writes:

XM and Sirius systems are available at your local truckstop

Is that what they're calling "HD Radio?" Sheesh! Sounds like the old
marketing philosoply that when a new product is sluggish, rename it
and get someone to write an article about it like it was new.

Since they call that "Satellite radio" I figured that those systems
received directly from the satellites, though I wondered about how
they do it without a serious antenna. They receive something in the FM
broadcast band?



--
I'm really Mike Rivers - )

HD Radio has a brand new codec, "HDC," which is based on similar
technology to AAC+SBR. The FM system, at 96 kbps, sounds excellent -- you
don't realize how much quality FM loses to the 75 us pre-emphasis curve
(which costs 17 dB of headroom at 15 kHz) until you compare it with a
"flat" transmission channel. The digital channel sounds far and away
superior to the analog channel, with a vanishingly low noise floor, no HF
headroom limitations, and no multipath distortion.

Thanks to HDC, HD AM at 36 bkps is NOT a joke. It's definitely
"entertainment-quality." The main artifact is some HF grittiness, as
opposed to the "underwater" sound of earlier-technology codecs at these
very low bit rates. Compared to analog AM sound, it's a night and day
difference.

Very few people have heard the HDC codec yet, but anyone who has heard
AAC+SBR will have a very good idea of its sonic capabilities. If you
haven't carefully auditioned AAC+SBR, you are in no position to form an
opinion about HD Radio. Any experience with MP3 is simply irrelevant to
this technology; the HDC codec artifacts sound completely different from
MP3's, and are much less obtrusive at any given bit rate.

In article , says...


Gang,
The current issue of "Pro Audio Review" is dedicated to "HD Radio."
Although not always called by this name, it's been coming for about 15
years. Now that digital satellite radio is making its initial splash
(IT'S THE CONTENT, STUPID), American broadcasters may reluctantly roll
out what is basically "mp3 radio." Sorry, but data-compressed digital
audio is just not going to be a step up in quality for terrestrial
broadcasters, IMNSHO.

But that's not even my beef. Frank Foti states that, upstream of the
new digital delivery orifice, "Care should be taken to avoid using heavy
dynamics processing such as high ratio limiting, clipping of any sort,
as well as radical EQ curves...." Oh. So the new HD radio is going to
wreak havoc on anything that's heavily compressed. Is that all?

Is there some law that I don't know about that compels people to come up
with the most useless new products and standards possible? Why
wouldn't any new compression algorithm take into account the LIKELY
SOURCE MATERIAL - heavily-compressed songs and commercials?!?

I spent 13 years in radio and still produce content for the medium. I'm
baffled. If the intent is to make everyone smash their Smashalizers,
I'll vote for that. Twice. But don't we have about 30 years of
highly-compressed back-catalog to somehow now "de-compress" to make it
work on this cool new digital radio thingy? Perhaps Mr. Foti is working
on an UnProcessor....?

Yours,
Dan Popp
Colors Audio

HD Radio has a brand new codec, "HDC," which is based on similar
technology to AAC+SBR. The FM system, at 96 kbps, sounds excellent -- you
don't realize how much quality FM loses to the 75 us pre-emphasis curve
(which costs 17 dB of headroom at 15 kHz) until you compare it with a
"flat" transmission channel. The digital channel sounds far and away
superior to the analog channel, with a vanishingly low noise floor, no HF
headroom limitations, and no multipath distortion.

Thanks to HDC, HD AM at 36 bkps is NOT a joke. It's definitely
"entertainment-quality." The main artifact is some HF grittiness, as
opposed to the "underwater" sound of earlier-technology codecs at these
very low bit rates. Compared to analog AM sound, it's a night and day
difference.

Very few people have heard the HDC codec yet, but anyone who has heard
AAC+SBR will have a very good idea of its sonic capabilities. If you
haven't carefully auditioned AAC+SBR, you are in no position to form an
opinion about HD Radio. Any experience with MP3 is simply irrelevant to
this technology; the HDC codec artifacts sound completely different from
MP3's, and are much less obtrusive at any given bit rate.

In article , says...


Gang,
The current issue of "Pro Audio Review" is dedicated to "HD Radio."
Although not always called by this name, it's been coming for about 15
years. Now that digital satellite radio is making its initial splash
(IT'S THE CONTENT, STUPID), American broadcasters may reluctantly roll
out what is basically "mp3 radio." Sorry, but data-compressed digital
audio is just not going to be a step up in quality for terrestrial
broadcasters, IMNSHO.

But that's not even my beef. Frank Foti states that, upstream of the
new digital delivery orifice, "Care should be taken to avoid using heavy
dynamics processing such as high ratio limiting, clipping of any sort,
as well as radical EQ curves...." Oh. So the new HD radio is going to
wreak havoc on anything that's heavily compressed. Is that all?

Is there some law that I don't know about that compels people to come up
with the most useless new products and standards possible? Why
wouldn't any new compression algorithm take into account the LIKELY
SOURCE MATERIAL - heavily-compressed songs and commercials?!?

I spent 13 years in radio and still produce content for the medium. I'm
baffled. If the intent is to make everyone smash their Smashalizers,
I'll vote for that. Twice. But don't we have about 30 years of
highly-compressed back-catalog to somehow now "de-compress" to make it
work on this cool new digital radio thingy? Perhaps Mr. Foti is working
on an UnProcessor....?

Yours,
Dan Popp
Colors Audio

From: Robert Orban

Very few people have heard the HDC codec yet, but anyone who has heard
AAC+SBR will have a very good idea of its sonic capabilities. If you
haven't carefully auditioned AAC+SBR, you are in no position to form an
opinion about HD Radio. Any experience with MP3 is simply irrelevant to
this technology; the HDC codec artifacts sound completely different from
MP3's, and are much less obtrusive at any given bit rate.


Personally, the AM is still too gritty and "underwater" sounding especially on
dense audio. As far as hearing the "new" SBR enchanced audio...anyone with some
time to kill can listen to them on the WOR web site:
http://www.wor710.com/Engineering/ib...io_samples.htm

It's better, but *not* hi-fi yet. Also, note that the analog samples were
limited at mono 5khz, yet analog AM *can* be stereo 10khz.


-Brad Jackson
-WGLD/WFMS/WGRL Indianapolis

From: Robert Orban

Very few people have heard the HDC codec yet, but anyone who has heard
AAC+SBR will have a very good idea of its sonic capabilities. If you
haven't carefully auditioned AAC+SBR, you are in no position to form an
opinion about HD Radio. Any experience with MP3 is simply irrelevant to
this technology; the HDC codec artifacts sound completely different from
MP3's, and are much less obtrusive at any given bit rate.


Personally, the AM is still too gritty and "underwater" sounding especially on
dense audio. As far as hearing the "new" SBR enchanced audio...anyone with some
time to kill can listen to them on the WOR web site:
http://www.wor710.com/Engineering/ib...io_samples.htm

It's better, but *not* hi-fi yet. Also, note that the analog samples were
limited at mono 5khz, yet analog AM *can* be stereo 10khz.


-Brad Jackson
-WGLD/WFMS/WGRL Indianapolis

In article , bradleyj
ADSPAM says...


From: Robert Orban

Very few people have heard the HDC codec yet, but anyone who has
heard
AAC+SBR will have a very good idea of its sonic capabilities. If you
haven't carefully auditioned AAC+SBR, you are in no position to form
an
opinion about HD Radio. Any experience with MP3 is simply irrelevant
to
this technology; the HDC codec artifacts sound completely different
from
MP3's, and are much less obtrusive at any given bit rate.


Personally, the AM is still too gritty and "underwater" sounding
especially on
dense audio. As far as hearing the "new" SBR enchanced audio...
anyone with some
time to kill can listen to them on the WOR web site:
http://www.wor710.com/Engineering/ib...io_samples.htm

It's better, but *not* hi-fi yet. Also, note that the analog samples were
limited at mono 5khz, yet analog AM *can* be stereo 10khz.

I didn't say HDC at 36 kbps was "hi-fi." However, IMO it is definitely "
entertainment quality," meaning that the average member of the mass
radio audience can listen to the program with enjoyment without being
unduly distracted by the artifacts.

Analog AM cannot have 10 kHz bandwidth in the real world because of
the absolute need for a 10 kHz notch filter (to remove carrier beats). A
typical NRSC audio processor is flat to 9.5 kHz, and I don't know of any
radios that come even close to that audio bandwidth. The Delco AM
stereo radios, for example, were about 6 kHz.

Moreover, analog AM still suffers from static, man-made noise (mostly in
the form of various buzzes related to the 60 Hz line frequency), plus
adjacent and co-channel interference. Taken together, all of these factors
have led to very aggressive audio processing just to maximize coverage.

The HD AM system has a vanishingly low noise floor. Interference, if
strong enough, can cause the digital signal to be undecodable in the
receiver, but, below that threshold, does not cause any audible
disturbances.

In short, HD AM can make AM a viable music medium for the mass
audience once again.

In article , bradleyj
ADSPAM says...


From: Robert Orban

Very few people have heard the HDC codec yet, but anyone who has
heard
AAC+SBR will have a very good idea of its sonic capabilities. If you
haven't carefully auditioned AAC+SBR, you are in no position to form
an
opinion about HD Radio. Any experience with MP3 is simply irrelevant
to
this technology; the HDC codec artifacts sound completely different
from
MP3's, and are much less obtrusive at any given bit rate.


Personally, the AM is still too gritty and "underwater" sounding
especially on
dense audio. As far as hearing the "new" SBR enchanced audio...
anyone with some
time to kill can listen to them on the WOR web site:
http://www.wor710.com/Engineering/ib...io_samples.htm

It's better, but *not* hi-fi yet. Also, note that the analog samples were
limited at mono 5khz, yet analog AM *can* be stereo 10khz.

I didn't say HDC at 36 kbps was "hi-fi." However, IMO it is definitely "
entertainment quality," meaning that the average member of the mass
radio audience can listen to the program with enjoyment without being
unduly distracted by the artifacts.

Analog AM cannot have 10 kHz bandwidth in the real world because of
the absolute need for a 10 kHz notch filter (to remove carrier beats). A
typical NRSC audio processor is flat to 9.5 kHz, and I don't know of any
radios that come even close to that audio bandwidth. The Delco AM
stereo radios, for example, were about 6 kHz.

Moreover, analog AM still suffers from static, man-made noise (mostly in
the form of various buzzes related to the 60 Hz line frequency), plus
adjacent and co-channel interference. Taken together, all of these factors
have led to very aggressive audio processing just to maximize coverage.

The HD AM system has a vanishingly low noise floor. Interference, if
strong enough, can cause the digital signal to be undecodable in the
receiver, but, below that threshold, does not cause any audible
disturbances.

In short, HD AM can make AM a viable music medium for the mass
audience once again.

"Robert Orban" wrote in message
...

In short, HD AM can make AM a viable music medium for the mass
audience once again.

Well, AM is pretty much where my radio sits without HD AM - WSM 650AM for
real country music, WNSG for black gospel.

I guess I just listen through the noise...

--
Dave Martin
Java Jive Studio
Nashville, TN
www.javajivestudio.com

"Robert Orban" wrote in message
...

In short, HD AM can make AM a viable music medium for the mass
audience once again.

Well, AM is pretty much where my radio sits without HD AM - WSM 650AM for
real country music, WNSG for black gospel.

I guess I just listen through the noise...

--
Dave Martin
Java Jive Studio
Nashville, TN
www.javajivestudio.com

From: Robert Orban
I didn't say HDC at 36 kbps was "hi-fi." However, IMO it is definitely "
entertainment quality," meaning that the average member of the mass
radio audience can listen to the program with enjoyment without being
unduly distracted by the artifacts.


OK...But what about the legacy analog signal that 99.9% of your audience will
hear? Can they listen to telephone quality 5khz mono audio and be entertained?
And with most AM being talk, will 99% of the public buy these new radios to
hear Dr. Laura in "near hi-fi"?


Analog AM cannot have 10 kHz bandwidth in the real world because of
the absolute need for a 10 kHz notch filter (to remove carrier beats). A
typical NRSC audio processor is flat to 9.5 kHz, and I don't know of any
radios that come even close to that audio bandwidth. The Delco AM
stereo radios, for example, were about 6 kHz.


I can name several of my radios that reach at least 10khz audio...My Carver
tx-11a is flat out to 15khz (A non-issue these days)...A GE SuperRadio III is
flat out to 12.5khz in wide mode...The AM Stereo Delco radios are flat out to
7.5 khz then a gradual decline to 10khz, And the Chrysler/Infinity Gold AM
Stereo radios have a 6.5khz filter but are only 6db down at 9.5khz. There is
even a cheap $5 Lennox Radio at Wal-Mart that is measured flat to 7khz!

Now I'll agree that 95% of the AM radios on the market suck, but isn't that a
manfacturer issue more than a broadcaster issue? Why punish the people with
decent analog radios with 5khz, hissy sideband audio?


In short, HD AM can make AM a viable music medium for the mass
audience once again.


But, in the meantime, we'll have to suffer through 5khz muddy audio, which will
drive even more of the music *away* from AM.

-Brad Jackson
-WGLD/WFMS/WGRL Indianapolis

From: Robert Orban
I didn't say HDC at 36 kbps was "hi-fi." However, IMO it is definitely "
entertainment quality," meaning that the average member of the mass
radio audience can listen to the program with enjoyment without being
unduly distracted by the artifacts.


OK...But what about the legacy analog signal that 99.9% of your audience will
hear? Can they listen to telephone quality 5khz mono audio and be entertained?
And with most AM being talk, will 99% of the public buy these new radios to
hear Dr. Laura in "near hi-fi"?


Analog AM cannot have 10 kHz bandwidth in the real world because of
the absolute need for a 10 kHz notch filter (to remove carrier beats). A
typical NRSC audio processor is flat to 9.5 kHz, and I don't know of any
radios that come even close to that audio bandwidth. The Delco AM
stereo radios, for example, were about 6 kHz.


I can name several of my radios that reach at least 10khz audio...My Carver
tx-11a is flat out to 15khz (A non-issue these days)...A GE SuperRadio III is
flat out to 12.5khz in wide mode...The AM Stereo Delco radios are flat out to
7.5 khz then a gradual decline to 10khz, And the Chrysler/Infinity Gold AM
Stereo radios have a 6.5khz filter but are only 6db down at 9.5khz. There is
even a cheap $5 Lennox Radio at Wal-Mart that is measured flat to 7khz!

Now I'll agree that 95% of the AM radios on the market suck, but isn't that a
manfacturer issue more than a broadcaster issue? Why punish the people with
decent analog radios with 5khz, hissy sideband audio?


In short, HD AM can make AM a viable music medium for the mass
audience once again.


But, in the meantime, we'll have to suffer through 5khz muddy audio, which will
drive even more of the music *away* from AM.

-Brad Jackson
-WGLD/WFMS/WGRL Indianapolis

"Robert Orban" wrote in message


HD Radio has a brand new codec, "HDC," which is based on similar
technology to AAC+SBR. The FM system, at 96 kbps, sounds excellent --
you don't realize how much quality FM loses to the 75 us pre-emphasis
curve (which costs 17 dB of headroom at 15 kHz) until you compare it
with a "flat" transmission channel. The digital channel sounds far
and away superior to the analog channel, with a vanishingly low noise
floor, no HF headroom limitations, and no multipath distortion.

These would be interesting samples to listen to, as well.

Thanks to HDC, HD AM at 36 bkps is NOT a joke. It's definitely
"entertainment-quality." The main artifact is some HF grittiness, as
opposed to the "underwater" sound of earlier-technology codecs at
these very low bit rates. Compared to analog AM sound, it's a night
and day difference.

FWIW I think I agree.

What I think would be the *obvious* comparison is not supported by the web
page at http://www.wor710.com/Engineering/ib...io_samples.htm That would
be the same music after typical analog FM processing. I say this because at
first blush the HDC samples sound more to me like analog FM than AM.

Cursory analysis shows that the "digital" signal has approximately 14 KHz
bandpass, in some sense. Yet it sounds muted and confused to me compared to
the original source material brick-walled at 14 KHz by Adobe Audition's FFT
filter.

Dynamics processing really has nothing to do with HDC, right? It's pretty
obvious in the HDC and analog samples. I wonder what the HDC and analog
samples would sound like without the heavy-handed dynamics processing.

In article , says...


"Robert Orban" wrote in message


HD Radio has a brand new codec, "HDC," which is based on similar
technology to AAC+SBR. The FM system, at 96 kbps, sounds excellent --
you don't realize how much quality FM loses to the 75 us pre-emphasis
curve (which costs 17 dB of headroom at 15 kHz) until you compare it
with a "flat" transmission channel. The digital channel sounds far
and away superior to the analog channel, with a vanishingly low noise
floor, no HF headroom limitations, and no multipath distortion.

These would be interesting samples to listen to, as well.

Thanks to HDC, HD AM at 36 bkps is NOT a joke. It's definitely
"entertainment-quality." The main artifact is some HF grittiness, as
opposed to the "underwater" sound of earlier-technology codecs at
these very low bit rates. Compared to analog AM sound, it's a night
and day difference.

FWIW I think I agree.

What I think would be the *obvious* comparison is not supported by the web
page at http://www.wor710.com/Engineering/ib...io_samples.htm That would
be the same music after typical analog FM processing. I say this because at
first blush the HDC samples sound more to me like analog FM than AM.

Cursory analysis shows that the "digital" signal has approximately 14 KHz
bandpass, in some sense. Yet it sounds muted and confused to me compared to
the original source material brick-walled at 14 KHz by Adobe Audition's FFT
filter.

Dynamics processing really has nothing to do with HDC, right? It's pretty
obvious in the HDC and analog samples. I wonder what the HDC and analog
samples would sound like without the heavy-handed dynamics processing.

It's true that dynamics processing has nothing to do with the HDC codec.
However, it's wise to use light dynamics processing on the digital HD AM
channel in order to have it sound consistent and "big-time." If you listen to
output of a broadcast mixing console, what comes out is assuredly not ready
for prime time. There is too much textural and loudness variation from source
to source to make the overall presentation sound smooth and listenable.
_Light_ AGC+multiband processing will smooth things out without overly
compromising the musicality of the sources.

Your perception of "confused sound" on the 36 kbps HDC codec may have
something to do with the stereo coding that's used at these low bit rates,
which doesn't fully preserve the original soundstage. For the mass radio
audience, "soundstage" is a foreign and irrelevant concept, however.

In article , says...


"Robert Orban" wrote in message


HD Radio has a brand new codec, "HDC," which is based on similar
technology to AAC+SBR. The FM system, at 96 kbps, sounds excellent --
you don't realize how much quality FM loses to the 75 us pre-emphasis
curve (which costs 17 dB of headroom at 15 kHz) until you compare it
with a "flat" transmission channel. The digital channel sounds far
and away superior to the analog channel, with a vanishingly low noise
floor, no HF headroom limitations, and no multipath distortion.

These would be interesting samples to listen to, as well.

Thanks to HDC, HD AM at 36 bkps is NOT a joke. It's definitely
"entertainment-quality." The main artifact is some HF grittiness, as
opposed to the "underwater" sound of earlier-technology codecs at
these very low bit rates. Compared to analog AM sound, it's a night
and day difference.

FWIW I think I agree.

What I think would be the *obvious* comparison is not supported by the web
page at http://www.wor710.com/Engineering/ib...io_samples.htm That would
be the same music after typical analog FM processing. I say this because at
first blush the HDC samples sound more to me like analog FM than AM.

Cursory analysis shows that the "digital" signal has approximately 14 KHz
bandpass, in some sense. Yet it sounds muted and confused to me compared to
the original source material brick-walled at 14 KHz by Adobe Audition's FFT
filter.

Dynamics processing really has nothing to do with HDC, right? It's pretty
obvious in the HDC and analog samples. I wonder what the HDC and analog
samples would sound like without the heavy-handed dynamics processing.

It's true that dynamics processing has nothing to do with the HDC codec.
However, it's wise to use light dynamics processing on the digital HD AM
channel in order to have it sound consistent and "big-time." If you listen to
output of a broadcast mixing console, what comes out is assuredly not ready
for prime time. There is too much textural and loudness variation from source
to source to make the overall presentation sound smooth and listenable.
_Light_ AGC+multiband processing will smooth things out without overly
compromising the musicality of the sources.

Your perception of "confused sound" on the 36 kbps HDC codec may have
something to do with the stereo coding that's used at these low bit rates,
which doesn't fully preserve the original soundstage. For the mass radio
audience, "soundstage" is a foreign and irrelevant concept, however.

I wouldn't describe 5 kHz audio as "muddy." Indeed, for many years, this was
the bandwidth of network television audio and was well-accepted by the mass
audience. It certainly has absolutely no "air," but, if anything, it can sound
a bit ringy and shrill (not "muddy") if the 5 kHz bandwidth limitation is
created by a sharply selective filter.

OTOH, the typical AM radio these days has an audio bandwidth of 2.5 kHz.
THAT'S muddy. Indeed, it's not really adequate for intelligible speech unless
the broadcast is pre-emphasized at the transmitter. Audio that is sharply
bandlimited to 5 kHz matches a receiver with a 2.5 - 3 kHz audio bandwidth
pretty well because the pre-5 kHz rolloff greatly mitgates the ringy sound of
the 5 kHz filter.

5 kHz bandwidth limitation also has another advantage (irrelevant to the
digital AM discussion) -- absent the digital AM sidebands, 5 kHz audio
completely protects first adjacent channels. At night, this can be a big
deal, and this remains a serious concern with the HD AM system. Indeed, when I
was heavily involved with the NRSC committee that came up with the NRSC1 and
NRSC2 standards, the broadcast interests had to fight against Delco to prevent
a 5 kHz filter from becoming the NRSC standard (a similar filter is already
recommedned in Europe by EBU standards). Delco wanted the 5 kHz filter to
prevent interference, which they claimed that many of their customers objected
to. According to Delco, these customers would try to listen to stations
outside their designated market areas and would sometimes return radios to
dealers if they felt that the radio in their new card didn't pick up as well
as their old radio did.

The 10 kHz filter was a compromise between the receiver manufacturers and
broadcasters that permitted higher quality sound while still protecting
second-adjacent channels. My own personal preference would have been to
mandate 10 kHz during the day and 5 kHz at night, which would have limited all
nighttime interference to co-channel only.

In article ,
ADSPAM says...


From: Robert Orban
I didn't say HDC at 36 kbps was "hi-fi." However, IMO it is definitely "
entertainment quality," meaning that the average member of the mass
radio audience can listen to the program with enjoyment without being
unduly distracted by the artifacts.


OK...But what about the legacy analog signal that 99.9% of your audience will
hear? Can they listen to telephone quality 5khz mono audio and be
entertained?
And with most AM being talk, will 99% of the public buy these new radios to
hear Dr. Laura in "near hi-fi"?


Analog AM cannot have 10 kHz bandwidth in the real world because of
the absolute need for a 10 kHz notch filter (to remove carrier beats). A
typical NRSC audio processor is flat to 9.5 kHz, and I don't know of any
radios that come even close to that audio bandwidth. The Delco AM
stereo radios, for example, were about 6 kHz.


I can name several of my radios that reach at least 10khz audio...My Carver
tx-11a is flat out to 15khz (A non-issue these days)...A GE SuperRadio III is
flat out to 12.5khz in wide mode...The AM Stereo Delco radios are flat out to
7.5 khz then a gradual decline to 10khz, And the Chrysler/Infinity Gold AM
Stereo radios have a 6.5khz filter but are only 6db down at 9.5khz. There is
even a cheap $5 Lennox Radio at Wal-Mart that is measured flat to 7khz!

Now I'll agree that 95% of the AM radios on the market suck, but isn't that a
manfacturer issue more than a broadcaster issue? Why punish the people with
decent analog radios with 5khz, hissy sideband audio?


In short, HD AM can make AM a viable music medium for the mass
audience once again.


But, in the meantime, we'll have to suffer through 5khz muddy audio, which
will
drive even more of the music *away* from AM.

-Brad Jackson
-WGLD/WFMS/WGRL Indianapolis

I wouldn't describe 5 kHz audio as "muddy." Indeed, for many years, this was
the bandwidth of network television audio and was well-accepted by the mass
audience. It certainly has absolutely no "air," but, if anything, it can sound
a bit ringy and shrill (not "muddy") if the 5 kHz bandwidth limitation is
created by a sharply selective filter.

OTOH, the typical AM radio these days has an audio bandwidth of 2.5 kHz.
THAT'S muddy. Indeed, it's not really adequate for intelligible speech unless
the broadcast is pre-emphasized at the transmitter. Audio that is sharply
bandlimited to 5 kHz matches a receiver with a 2.5 - 3 kHz audio bandwidth
pretty well because the pre-5 kHz rolloff greatly mitgates the ringy sound of
the 5 kHz filter.

5 kHz bandwidth limitation also has another advantage (irrelevant to the
digital AM discussion) -- absent the digital AM sidebands, 5 kHz audio
completely protects first adjacent channels. At night, this can be a big
deal, and this remains a serious concern with the HD AM system. Indeed, when I
was heavily involved with the NRSC committee that came up with the NRSC1 and
NRSC2 standards, the broadcast interests had to fight against Delco to prevent
a 5 kHz filter from becoming the NRSC standard (a similar filter is already
recommedned in Europe by EBU standards). Delco wanted the 5 kHz filter to
prevent interference, which they claimed that many of their customers objected
to. According to Delco, these customers would try to listen to stations
outside their designated market areas and would sometimes return radios to
dealers if they felt that the radio in their new card didn't pick up as well
as their old radio did.

The 10 kHz filter was a compromise between the receiver manufacturers and
broadcasters that permitted higher quality sound while still protecting
second-adjacent channels. My own personal preference would have been to
mandate 10 kHz during the day and 5 kHz at night, which would have limited all
nighttime interference to co-channel only.

In article ,
ADSPAM says...


From: Robert Orban
I didn't say HDC at 36 kbps was "hi-fi." However, IMO it is definitely "
entertainment quality," meaning that the average member of the mass
radio audience can listen to the program with enjoyment without being
unduly distracted by the artifacts.


OK...But what about the legacy analog signal that 99.9% of your audience will
hear? Can they listen to telephone quality 5khz mono audio and be
entertained?
And with most AM being talk, will 99% of the public buy these new radios to
hear Dr. Laura in "near hi-fi"?


Analog AM cannot have 10 kHz bandwidth in the real world because of
the absolute need for a 10 kHz notch filter (to remove carrier beats). A
typical NRSC audio processor is flat to 9.5 kHz, and I don't know of any
radios that come even close to that audio bandwidth. The Delco AM
stereo radios, for example, were about 6 kHz.


I can name several of my radios that reach at least 10khz audio...My Carver
tx-11a is flat out to 15khz (A non-issue these days)...A GE SuperRadio III is
flat out to 12.5khz in wide mode...The AM Stereo Delco radios are flat out to
7.5 khz then a gradual decline to 10khz, And the Chrysler/Infinity Gold AM
Stereo radios have a 6.5khz filter but are only 6db down at 9.5khz. There is
even a cheap $5 Lennox Radio at Wal-Mart that is measured flat to 7khz!

Now I'll agree that 95% of the AM radios on the market suck, but isn't that a
manfacturer issue more than a broadcaster issue? Why punish the people with
decent analog radios with 5khz, hissy sideband audio?


In short, HD AM can make AM a viable music medium for the mass
audience once again.


But, in the meantime, we'll have to suffer through 5khz muddy audio, which
will
drive even more of the music *away* from AM.

-Brad Jackson
-WGLD/WFMS/WGRL Indianapolis