IBOC
 

I saw a reference to this and wondered what it was. Below is a link I found
using Google:

http://www.ibiquity.com/technology/index.htm

I can't see how it will do anything but cause serious problems for
shortwave, let alone AM. I don't fancy having to replace any radios I have.
Since people already have cell phones capable of sending and receiving
email, pictures and news, it would seem redundant. What would make people
want this over their existing cell phones ?

Il Dolce Far Niente

"Maximus" wrote in message
ink.net...
I saw a reference to this and wondered what it was. Below is a link I
found
using Google:

http://www.ibiquity.com/technology/index.htm

I can't see how it will do anything but cause serious problems for
shortwave, let alone AM.


There hasn't been any push to use IBOC on shortwave. It's been designed
for domestic AM and FM broadcasters. There's a different non-compatible
digital standard for shortwave called DRM.


I don't fancy having to replace any radios I have.


IBOC is sorta compatible with standard AM broadcasting. The standard AM
channel is still there, with additional channels of digital modulation
just above and below the standard channel. Unfortunately, the fidelity
of the standard channel must be reduced, and the digital channels can
cause severe interference with adjacent channels. IBOC isn't compatible
with DXing stations close in frequency to an IBOC station, and buying
another radio won't help.


Since people already have cell phones capable of sending and receiving
email, pictures and news, it would seem redundant. What would make
people
want this over their existing cell phones ?


Even the "journalists" who do little more than reword corporate press
handouts aren't showing much enthusisiam for IBOC broadcasting to cell
phones. Anyway, I'd expect the IBOC cell phone broadcasters will be
trying FM band transmitters rather than AM band transmitters.

There are claims that there is a great unfilled demand for slow text and
low-res graphics and pictures on our radios and, by golly, the IBOC folk
will step up to the plate and fufill that demand. Imagine that!
Pictures on the radio. What will they think of next?

Frank Dresser

I can't see how it will do anything but cause serious problems for
shortwave, let alone AM.


You won't hear much of anything under 400 mhz once broadband over power lines ramps up to full
bore.

Do a gOOgle search on BPL,

Steve

"Steve Stone" wrote in message
et...

You won't hear much of anything under 400 mhz once broadband over
power lines ramps up to full
bore.

Do a gOOgle search on BPL,

Steve

I'm lazy. How 'bout you gOOgle up some links concerning this "You won't
hear much of anything under 400 mhz " business?

Oh, yeah. Don't forget to share your knowledge with the TV and radio
networks. For some reason, they don't seem concerned.

Frank Dresser

"Frank Dresser" wrote in message
...

"Steve Stone" wrote in message
et...

You won't hear much of anything under 400 mhz once broadband over
power lines ramps up to full
bore.

Do a gOOgle search on BPL,

Steve

I'm lazy. How 'bout you gOOgle up some links concerning this "You won't
hear much of anything under 400 mhz " business?

Oh, yeah. Don't forget to share your knowledge with the TV and radio
networks. For some reason, they don't seem concerned.

400 MHz is a bit of an exaggeration. BPL will cause considerable
interference up to it's limit of 75MHz, and may cause some harmonic
interference above that (it IS square wave after all, and high in harmonic
content).

It won't (or shouldn't) affect the AMBCB, since it is supposed to start at
1.8 MHz. However, there have been several tests performed by hams and some
labs (see the ARRL website www.arrl.org), and several countries have already
banned BPL because of extreme interference to other services, including HF
broadcast and amateur radio services. I don't remember the exact numbers,
but basically if you are within 30 feet of a BPL line, you will receive in
excess of S9 (some tests have shown 30 dB over S9) of interference.

"Brenda Ann" wrote in message
...


400 MHz is a bit of an exaggeration. BPL will cause considerable
interference up to it's limit of 75MHz, and may cause some harmonic
interference above that (it IS square wave after all, and high in
harmonic
content).


Oh, I know. I've done my fair share of usenet posts on the BPL topic.
The original poster makes a very good point, though. It is easy to
research.



It won't (or shouldn't) affect the AMBCB, since it is supposed to
start at
1.8 MHz. However, there have been several tests performed by hams and
some
labs (see the ARRL website www.arrl.org), and several countries have
already
banned BPL because of extreme interference to other services,
including HF
broadcast and amateur radio services. I don't remember the exact
numbers,
but basically if you are within 30 feet of a BPL line, you will
receive in
excess of S9 (some tests have shown 30 dB over S9) of interference.



I really doubt BPL will have any noticable effects on AM/FM/TV
reception. After all, the networks haven't used any of their
considerable clout in Washington in the BPL fight. I suspect consumer
electronics will be most subject to any BPL effects throught the power
cord and not the antenna terminals. If this has been a problem in the
test areas, I'm not aware of it.

But I wonder if BPL will work as promised and if it will be a good deal
for the consumers. Power lines are an awfully primitave way to deliver
high speed access, and I can imgaine alot of problems. If BPL doesn't
work out, the utilities might have to fall back on BWP (Broadband over
Water Pipes).

Frank Dresser

In article ,
"Brenda Ann" wrote:

"Frank Dresser" wrote in message
...

"Steve Stone" wrote in message
et...

You won't hear much of anything under 400 mhz once broadband over
power lines ramps up to full
bore.

Do a gOOgle search on BPL,

Steve

I'm lazy. How 'bout you gOOgle up some links concerning this "You won't
hear much of anything under 400 mhz " business?

Oh, yeah. Don't forget to share your knowledge with the TV and radio
networks. For some reason, they don't seem concerned.

400 MHz is a bit of an exaggeration. BPL will cause considerable
interference up to it's limit of 75MHz, and may cause some harmonic
interference above that (it IS square wave after all, and high in harmonic
content).

It won't (or shouldn't) affect the AMBCB, since it is supposed to start at
1.8 MHz. However, there have been several tests performed by hams and some
labs (see the ARRL website www.arrl.org), and several countries have already
banned BPL because of extreme interference to other services, including HF
broadcast and amateur radio services. I don't remember the exact numbers,
but basically if you are within 30 feet of a BPL line, you will receive in
excess of S9 (some tests have shown 30 dB over S9) of interference.


Data communications occupy wider bandwidths than the stated clock rate.
It is not unreasonable to expect harmonics 3 to 5 times the clock rate
because the signaling uses square waves and there is significant power
in the odd harmonics.

--
Telamon
Ventura, California

"Telamon" wrote in message
...


Data communications occupy wider bandwidths than the stated clock
rate.
It is not unreasonable to expect harmonics 3 to 5 times the clock rate
because the signaling uses square waves and there is significant power
in the odd harmonics.

--
Telamon
Ventura, California

A square wave, itself, won't convey much information. It needs to be
modulated, and the modulation would have to effect the symmetry and
result in both odd and even harmonics.

I don't know what sort of modulation BPL is using. I can imagine
hundreds of low amplitude sine wave carriers from 2 to 60 Mhz, all of
them phase modulated. In that case, I don't think there would be much
harmonic output. This would certainly still be a big problem for the
radio hobbyist, but not so much for the FM/TV user. There have been
several BPL tests in various communities, and it doesn't seem to have
wiped out normal broadcast use.

If BPL caused enough bothersome interference to keep people in the test
communities from their TVs and radios, the National Association of
Broadcasters would have squashed it like a bug.

Frank Dresser

"Frank Dresser" wrote in message
...

"Telamon" wrote in message
...


Data communications occupy wider bandwidths than the stated clock
rate.
It is not unreasonable to expect harmonics 3 to 5 times the clock rate
because the signaling uses square waves and there is significant power
in the odd harmonics.

--
Telamon
Ventura, California

A square wave, itself, won't convey much information. It needs to be
modulated, and the modulation would have to effect the symmetry and
result in both odd and even harmonics.

I don't know what sort of modulation BPL is using. I can imagine
hundreds of low amplitude sine wave carriers from 2 to 60 Mhz, all of
them phase modulated. In that case, I don't think there would be much
harmonic output.

Digital comms are purely square waves. The modulation is FSK or similar
(generally)... in other words, the on-state is one frequency, the off state
is another. This creates a chain of square waves which themselves are not
modulated. The bandwidth, in this case 75 MHz, is how many on/off states
there are in one second. This is also concurrent with bitrate. Compression
schemes can raise the apparent bitrate, however the actual bitrate is the
same as the frequency used. I'm not sure how they do the band notching that
Japan tried before they tossed out the idea completely.

"Brenda Ann" wrote in message
...


Digital comms are purely square waves.

I'm using the term "square wave" to mean a sharp cornered pulse train
with an exactly 50% duty cycle. There's not much information there.
You've seen one pulse of the square wave, you've seen them all.


The modulation is FSK or similar
(generally)... in other words, the on-state is one frequency, the off
state
is another. This creates a chain of square waves which themselves are
not
modulated.

And the square wave is recovered after only after demodulation of the
sine waves. The modulation doesn't necessaraly create harmonics, but it
does create sidebands.

This guy likes to use triangle waves in his illustrations:

http://www.cs.ucl.ac.uk/staff/S.Bhat...es/node12.html


The bandwidth, in this case 75 MHz, is how many on/off states
there are in one second. This is also concurrent with bitrate.
Compression
schemes can raise the apparent bitrate, however the actual bitrate is
the
same as the frequency used.

The carriers can be both amplitude and phase modulated to increase
bitrate.

Given that the BPL is usually described as a spread spectrum technology,
I'll assume there's many carrier frequencies.

I'm not sure how they do the band notching that
Japan tried before they tossed out the idea completely.




Doesn't Japan have a higher percentage of SWLs and radio amateurs than
the US? I don't think most Americans will much care about BPL unless it
effects the TV. I'll bet the BPL traps at 3.58 MHz work just fine.

Frank Dresser