The typical AM receiver can not tell the difference between the reduced
IBOC-mandated analog bandwidth and a full NRSC bandwidth. In fact, I fidn
that the reduced transmitted bandwidth sounds better on many radios than
wider bandwidth.
It depends on how strongly the station is pushing their audio
processing and pre-emphasis. With moderate processing, like a
European shortwave station, you only notice the lack of high
frequencies. But with "make-your-ears-bleed" processing and
pre-emphasis pushed to the max, like what 710 WOR uses, that
brick-wall filter at 5 kHz can cause some very nasty "ringing"
distortion which becomes audible on receivers of any bandwidth. For
example, take a listen to how bad WOR sounds on their own modulation
monitor -- their analog audio is filled with ringing distortion, and
that's it's been ever since they started using IBOC....
http://www.wor710.com/Engineering/iboc/wor_mod_mon.wav
There are 700 million radios out there; most all of them have crummy AM
response.
Yes, but if we always catered to the lowest common denominator, then
there would be no such thing as a sports car, McDonald's would be
considered fine dining, Emerson and Realistic would be the leading
brands of "high-end audio", and George W. Bush would be President (oh,
wait -- scratch that one).
It does not degrade analog FM at all; on AM I feel the degradation looks bad
on paper, but in reality it is insignificant and may be an improvment.
Well, imagine if all the Class C "graveyard channel" stations started
using IBOC -- would the mutually assured destruction caused by that be
"insignificant"?
The said the same thing about CD players, VHS players and DVD players. I
paid over $700 for my first VHS; $1200 for my first CD player. And the tapes
and CDs were very expensive to start.
But CDs still cost more than cassettes, even though they are far
cheaper to manufacture. And don't expect an HD Radio Walkman any time
soon -- the battery drain is far too high to useable on the typical
pair of AA cells.
Listeners outside the metro are do not afford most stations any opportunity
for extra revenue.
Many areas of the country rely upon fringe-area reception to have any
AM/FM radio at all. I'm very close to one such area -- central NJ,
which is halfway between NYC and Philly and thus almost every adjacent
FM channel is occupied with a signal that is "non-local" but is
listenable. Now that NYC's 102.7 WNEW has begun using IBOC, in some
areas all you hear on 102.5 and 102.9 is a constant white-noise hiss,
much to the consternation of any fringe-area listeners of Philly's
102.9 WMGK.
I am listening daily to an LA music AM in IBOC digital and the audio is
crisp, nice, clear, and very listenable. It is nothing like you say.
Well then, I invite you to listen to WOR's audio samples, made with
the new "HDC" codec -- spectrum analysis reveals that all audio above
5 kHz is artificially created using "spectral replication". Even
WOR's engineers admit that this sometimes causes the digital audio to
sound "shredded", due to the incorrectly reproduced treble
harmonics.....
http://www.wor710.com/Engineering/ib...io_samples.htm
XM and IBOC have different systems.
Both use AACplus with Spectral Band Replication. XM uses it at a
claimed average of 64 kbps for music channels, while IBOC-AM is 36
kbps for stereo mode and 20 kbps for mono mode, and IBOC-FM is at
either 64 or 96 kbps -- which is still far from the claimed
"CD-quality" sound.
We tested with a bunch or receivers, rnging from clock radios to boom boxes
to walma n type devices. None of us could tell any significant difference in
A/B testing.
Next time you are in NYC, switch between 710 WOR and 770 WABC, even on
the crappiest, most narrow-bandwidth AM radio you can find. WOR's
IBOC signal might sound "okay", but once you switch to WABC, the
difference in clarity is immediately noticeable. Due to their
maxed-out audio processing, WOR may be "louder", but WABC sounds a
whole lot cleaner.
Near 3 weeks of operation, not one listener comment on the analog signal.
WOR listeners have complained to the _electric company_, thinking that
the IBOC "hash" surrounding their signal was power line interference.
And most listeners never call a radio station for any reason. Many
times when a station is off the air, is transmitting dead air, or has
other obvious problems, nobody calls.
Any experiments were to determne the insertion level for IBOC for porposed
night operation.
Regardless of the purpose, WSAI shouldn't be transmitting IBOC at
night -- their STA to do so expired back in September, and the FCC
database shows no record of a renewal. WSAI is not properly marked in
the database as a hybrid digital station, either.
And good luck airing any New Year's celebration on an IBOC station --
unless you kill the analog delay, the count-down to midnight will be
about 8½ seconds late.