Please enlighten me: Why is IBOC so Evil?

tom k in L.A. wrote:
Please enlighten me: Why is IBOC so Evil?

Because it's new, and we can't have new stuff in a technology-related hobby?

[ducks]

-Luke

On Jan 23, 10:52 pm, "tom k in L.A." wrote:
Please enlighten me: Why is IBOC so Evil?

Because if wipes out adjacent 'weak' signals and the IBOC station
sounds
like crap if you are far enough away at night for sky wave to effect
the signal
at all.

For instance I live about 80 miles east of WHAS on 840KHz, and after
local
sunset they are unlistenable. Since they carry adverts for Lexington
businesses,
their business model clearly counts on revenue from Lexington. But
most
MW receivers fold after dark. Since I don't listen to MW it really
doesn't
effect me. But as an engineer I like to see effective and if possible
elegant
solutions. IBOC is neither.

Digital will have a place in the future of radio, but IBOC is the
wrong
solution for a non issue. With MW station revenues dropping, this
isn't
going to help them.

Terry

tom k in L.A. wrote:
Please enlighten me: Why is IBOC so Evil?

It causes interference and makes the analog signal sound like ****.

Why is iBiquity's IBOC Broadcast Technology So Evil ? - Please
Enlighten Me !
http://groups.google.com/group/hd-ra...481f18e1f4edce

On Jan 23, 5:52 pm, "tom k in L.A." wrote:
Please enlighten me: Why is IBOC so Evil?

If you have to ask the question - why is IBOC so evil? Then, I have to
question your basic understanding of broadcast modes and standards
that have been in place for decades. (And sanctioned by the FCC I
might add.)

Do your own research (there's plenty of info on the web) as well as
your own listeniing and then come back later and I'll quiz you.

jw

On Wed, 23 Jan 2008 14:52:57 -0800, tom k in L.A. wrote:

Please enlighten me: Why is IBOC so Evil?

The primary complaint is that the IBOC digital signal is transmitted in
two channels either side of the station using it, causing massive
interference.

For example, if a station on 1510kHz runs IBOC, the digital signals are
transmitted in 1495-1505kHz (interfering with stations on 1490 and 1500)
and from 1515-1525kHz. (interfering with 1520 and 1530kHz)

(on FM, only one frequency on each side is interfered with, and in many
cases those frequencies were already useless due to interference problems
involving the station's *analog* signal. It does make things hard on
FM DXers though.)

Other complaints:

- Poor coverage in the current "hybrid mode", where analog simulcasts must
be accomodated.

- Self-interference: if the station isn't balanced properly or the
receiver has an unusually wide IF bandwidth, the IBOC digital signal can
interfere with the station's own analog signal.

- We could have had something better. A system called "Eureka-147" is
seeing success in Britain and at least in technical terms across Europe.
This Eureka system would have offered improved fidelity over IBOC, more
subchannels, and no interference issues.

Doug Smith W9WI wrote:

On Wed, 23 Jan 2008 14:52:57 -0800, tom k in L.A. wrote:

Please enlighten me: Why is IBOC so Evil?

The primary complaint is that the IBOC digital signal is transmitted in
two channels either side of the station using it, causing massive
interference.

For example, if a station on 1510kHz runs IBOC, the digital signals are
transmitted in 1495-1505kHz (interfering with stations on 1490 and 1500)
and from 1515-1525kHz. (interfering with 1520 and 1530kHz)

That can be compared to an analog station on 1510. Its transmissions cover
from 1500-1520 kHz. This interferes with the stations on 1500 and 1520.
Adjacent channel interference is managed by keeping station apart both
geographically and frequency-wise. This may work during the day, but not at
night.


(on FM, only one frequency on each side is interfered with, and in many
cases those frequencies were already useless due to interference problems
involving the station's *analog* signal. It does make things hard on
FM DXers though.)

Other complaints:

- Poor coverage in the current "hybrid mode", where analog simulcasts must
be accomodated.

Poor coverage of the digital portion, the analog portion of the hybrid
signal still has the same coverage.


- Self-interference: if the station isn't balanced properly or the
receiver has an unusually wide IF bandwidth, the IBOC digital signal can
interfere with the station's own analog signal.

Yes, the higher fidelity receivers suffer more with than cheaper ones
because of the digital signals.


- We could have had something better. A system called "Eureka-147" is
seeing success in Britain and at least in technical terms across Europe.
This Eureka system would have offered improved fidelity over IBOC, more
subchannels, and no interference issues.

However, the FCC required a digital system to be compatible with analog.
Eureka-147 is not used in the AM band. This is not without issues, though.
Switching encoding from MPEG to AAC+ will obsolete many receivers.

An interesting note, the AM analog signals received on my IBOC receiver
sound better than that heard on almost any other AM receiver I own. The FM
on the receiver appears to have excellent selectivity also.

For me, FM IBOC works. The IBOC signals are clearer. The second program
offerred by some station does provide unique programming.

For me, AM IBOC is a waste. I can receive no AM digital transmissions. I do
hear the interference caused by the digital signals. (I am also 50 miles
from the nearest transmitter using IBOC.)

The FCC is managing the airwaves in a manner that does not support DXing.
They are focused on radio working in the local markets, not long distance
reception. The broadcasters are also focused on the local markets as that
is where the advertising revenue comes from. On AM, IBOC is attempting to
improve audio fidelity for listeners in the local markets. It may (or may
not) be working.

craigm

On Thu, 24 Jan 2008 08:20:02 -0600, craigm wrote:
For example, if a station on 1510kHz runs IBOC, the digital signals are
transmitted in 1495-1505kHz (interfering with stations on 1490 and 1500)
and from 1515-1525kHz. (interfering with 1520 and 1530kHz)

That can be compared to an analog station on 1510. Its transmissions cover
from 1500-1520 kHz. This interferes with the stations on 1500 and 1520.
Adjacent channel interference is managed by keeping station apart both
geographically and frequency-wise. This may work during the day, but not at
night.

The big difference here is that the portion of the analog signal that
extends into the 1500/1520 channels is that which results from modulation
products above 5kHz.

This high-frequency material, in an analog signal, is relatively weak and
infrequent. You might hear an occasional "crash" or "splash" from the
adjacent channel station, but it's not enough to annoy most listeners.

The IBOC digital sidebands are there *all the time* and *at full strength*.

However, the FCC required a digital system to be compatible with analog.
Eureka-147 is not used in the AM band. This is not without issues, though.
Switching encoding from MPEG to AAC+ will obsolete many receivers.

Arguably, Eureka is *more* compatible with analog - because it operates in
its own spectrum and doesn't interfere with the analog transmissions.

The choice of IBOC over Eureka was not originated by the
government. If the industry had asked for an out-of-band solution like
Eureka, they would have received it. It was the industry that insisted on
the IBOC system, for two reasons:

1. IBOC uses existing transmitting antennas. No need to find tower space
for new VHF/UHF transmitting antennas; no need to fight zoning battles.

2. IBOC maintains the relative coverage areas of existing stations and the
relative fidelity improvement of "FM" over "AM". Eureka would potentially
equalize the coverage areas of all stations in a market - allowing 3kW
"92Q" to fully compete with 100kW "101.1 The Beat".

Eureka doesn't operate in the AM band, but it would open enough spectrum
to allow for VHF/UHF digital assignments for existing AM stations.

Receiver obselence (sp?) issues would not have been issues if the Eureka
system had been chosen from the outset. At this point I think it's too
late to put the genie back in the bottle - either IBOC is going to
succeed, or digital radio is going to fail altogether in the U.S.. I
strongly suspect the latter.

An interesting note, the AM analog signals received on my IBOC
receiver
sound better than that heard on almost any other AM receiver I own. The
FM on the receiver appears to have excellent selectivity also.

Very true. IBOC receivers use DSP and that feature seems to work VERY
well. Furthermore, I've found my IBOC receiver is able to
effectively reject interference from adjacent-channel IBOC stations when
tuned to analog stations. As you say, the FM selectivity is also quite
good.

For me, FM IBOC works. The IBOC signals are clearer. The second
program
offerred by some station does provide unique programming.

I find no noticable difference in audio quality here. Our local NPR
station does offer a worthwhile HD2 subchannel.

I wonder about the long-term viability of HD2 subchannels on commercial
stations?

- How long can stations afford to continue operating HD2 subchannels
without selling airtime? If the music licensing fees increase or the HD2
encoder requires a $2,000 repair, will the station be willing to spend the
money knowing it's not going to bring in any revenue?

- If stations do begin selling airtime on their HD2's, how long can they
continue to carry unique formats? Do they have to start dropping the
"deep cuts" in favor of plain ol' classic rock to pull that extra point or
two?

The FCC is managing the airwaves in a manner that does not
support
DXing. They are focused on radio working in the local markets, not long
distance reception. The broadcasters are also focused on the local
markets as that is where the advertising revenue comes from. On AM, IBOC
is attempting to improve audio fidelity for listeners in the local
markets. It may (or may not) be working.

- In some cases, IBOC *is* interfering with local reception. Admittedly
relatively few cases.

- Who's being ignored here (as is often the case in telecommunications
policy...) are rural and suburban residents. Listeners who due to a
relatively quiet environment get good service from relatively distant
stations - and due to a greater distance from major cities, get "city
grade" service from relatively few stations.

At my location, only ONE AM station delivers an interference-free
nighttime groundwave signal. Only ONE AM station would be receivable in a
world where all AM stations ran IBOC 24/7. I am fully dependent on
skywave for any choice in nighttime AM.

And I'm not in rural Montana or Alaska. I'm in central Tennessee only 30
miles from Nashville. At least a million people in Tennessee alone are in
the same situation.

On Jan 23, 5:52 pm, "tom k in L.A." wrote:
Please enlighten me: Why is IBOC so Evil?

Because, it jams our airways on FM, and especially on AM. HD/IBOC is a
complete giveaway of our free airways to iBiquity and the HD Radio
Alliance - it is a total scam:

"HD Radio on the Offense"

"But after an investigation of HD Radio units, the stations playing
HD, and the company that owns the technology; and some interviews with
the wonks in DC, it looks like HD Radio is a high-level corporate
scam, a huge carny shill."

http://www.eastbayexpress.com/2007-0...on-the-offense

For more info:

http://hdradiofarce.blogspot.com/