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Old February 24th 04, 04:42 PM
David
 
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Default Spectrum plot of an IBOC AM station

Thanks to Bob Gonsett

http://earthsignals.com/add_CGC/KMXE.PDF
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Old February 24th 04, 06:31 PM
Maximus
 
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HD=? Looks like if you got too many of these things splattering all over
there would be lousy reception for sure. Not everybody can afford a $3000
receiver that could knock out either.

Il Dolce Far Niente

"David" wrote in message
news
Thanks to Bob Gonsett

http://earthsignals.com/add_CGC/KMXE.PDF



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Old February 24th 04, 07:38 PM
Frank Dresser
 
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"Maximus" wrote in message
ink.net...
HD=? Looks like if you got too many of these things splattering all

over
there would be lousy reception for sure. Not everybody can afford a

$3000
receiver that could knock out either.

Il Dolce Far Niente


It certainly would be tough to receive adjacent channels. I don't think
a $3000 radio would help much, because the IBOC sidebands are right on
the adjacent channels. It would be similiar to trying to receive a
distant station when a local is on the same frequency. And the local
station never gives it's continual noisy modulation a rest.

I suppose the best way to receive adjacent channels would be nulling the
sideband noise out with the antenna.

Frank Dresser


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Old February 24th 04, 07:38 PM
Frank Dresser
 
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"David" wrote in message
news
Thanks to Bob Gonsett

http://earthsignals.com/add_CGC/KMXE.PDF


Thanks for the link.

That spectrum is consistant with what I heard a few evenings ago around
720 kHz. WGN's engineer said it wasn't them, and I haven't noticed the
noise since then.

Has anyone heard the sidebands produced by IBOC? The best description I
can come up with is something like "digital white noise".

Frank Dresser


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Old February 24th 04, 08:15 PM
Ron Hardin
 
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Frank Dresser wrote:
That spectrum is consistant with what I heard a few evenings ago around
720 kHz. WGN's engineer said it wasn't them, and I haven't noticed the
noise since then.

Has anyone heard the sidebands produced by IBOC? The best description I
can come up with is something like "digital white noise".


It's just a noise rush, but not white exactly. The giveaway is that it's on
only one sideband of the station you're trying to hear. If you hear it on the
LSB, the offending IBOC station is 10 kHz higher (not lower as you'd expect);
and if on USB, then 10 kHz lower.

So you need selectable sidebands to tell, or at least a BFO and notice whether
the noise pitch goes up as you tune up (in which case the IBOC station is higher)
or goes down (in which case the IBOC station is lower), starting from the
interfered-with station.
--
Ron Hardin


On the internet, nobody knows you're a jerk.


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Old February 24th 04, 08:40 PM
Kevin Alfred Strom
 
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Ron Hardin wrote:

Frank Dresser wrote:
That spectrum is consistant with what I heard a few evenings ago around
720 kHz. WGN's engineer said it wasn't them, and I haven't noticed the
noise since then.

Has anyone heard the sidebands produced by IBOC? The best description I
can come up with is something like "digital white noise".


It's just a noise rush, but not white exactly. The giveaway is that it's on
only one sideband of the station you're trying to hear. If you hear it on the
LSB, the offending IBOC station is 10 kHz higher (not lower as you'd expect);
and if on USB, then 10 kHz lower.

So you need selectable sidebands to tell, or at least a BFO and notice whether
the noise pitch goes up as you tune up (in which case the IBOC station is higher)
or goes down (in which case the IBOC station is lower), starting from the
interfered-with station.

[...]


All of this destruction of the radio listening hobby -- and
destruction of _anyone's_ ability to listen to many of the more
distant or weaker stations he can now receive -- is because the
money-men of the media monopolies saw a new digital band as a threat
to their dominance. So they squelched it -- they hope -- with IBOC.

As I've said before, IBOC (In-Band On-Channel) digital -- AM or FM
-- is essentially a turkey, technically. It's inferior in almost
every way to a dedicated digital system in a dedicated digital band.

The main reason IBOC is promoted is because a new dedicated digital
band would level the playing field: the present 250-Watt AM
daytimer, once ensconced in the new band, would have just as clear
and clean a signal as the 50-Kw clear channel or the high-power FM
-- just as good fidelity, the same coverage, and 24-hour operation.
Just like your Web site is as clear and as easily accessible as
NBC's.

A dedicated digital band might also be scalable and allow many more
channels for the listener -- hundreds, thousands perhaps. Probably
enough to allow public access (in which anyone can be a broadcaster
for free or nearly free) on an even greater scale than does cable
television or Internet radio.

And that would mean more competition for the big-money men.

And it would mean that competition would now be purely on the basis
of programming, not the sheer signal superiority which the money-men
have paid for.

They want to preserve the _inferiority_ of their smaller
competitors. IBOC does that. They want to maintain the high economic
hurdle to becoming a broadcaster. IBOC does that.



With all good wishes,



--

Kevin Alfred Strom.

News: http://www.nationalvanguard.org/
The Works of R. P. Oliver: http://www.revilo-oliver.com
Personal site: http://www.kevin-strom.com
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Old February 24th 04, 11:37 PM
Frank Dresser
 
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"Ron Hardin" wrote in message
...

It's just a noise rush, but not white exactly. The giveaway is that

it's on
only one sideband of the station you're trying to hear. If you hear

it on the
LSB, the offending IBOC station is 10 kHz higher (not lower as you'd

expect);
and if on USB, then 10 kHz lower.



I'm not sure I understand. The spectrum plot shows two symmetrical
peaks off the carrier frequency. The noise I observed was consistant
with that.


So you need selectable sidebands to tell, or at least a BFO and notice

whether
the noise pitch goes up as you tune up (in which case the IBOC station

is higher)
or goes down (in which case the IBOC station is lower), starting from

the
interfered-with station.
--
Ron Hardin



I turned the BFO on, and scanned across the noise. I didn't think to try
to discriminate between a upper or lower sideband transmission. I was
trying to tell if there were multiple carriers in the sideband noise. I
don't think there was, but I wasn't checking it out very long. I played
with it for a couple of minutes, then I got on the computer to check if
there was an announcement of WGN was going IBOC. There wasn't, and by
the time I got back to the radio, everything was quiet. It's been quiet
since.

Frank Dresser


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Old February 24th 04, 11:38 PM
Frank Dresser
 
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Default


"Kevin Alfred Strom" wrote in message
...


All of this destruction of the radio listening hobby -- and
destruction of _anyone's_ ability to listen to many of the more
distant or weaker stations he can now receive -- is because the
money-men of the media monopolies saw a new digital band as a threat
to their dominance. So they squelched it -- they hope -- with IBOC.



As far as I know, the FCC has stopped all IBOC testing at night in
order to reduce interference with other stations.


As I've said before, IBOC (In-Band On-Channel) digital -- AM or FM
-- is essentially a turkey, technically. It's inferior in almost
every way to a dedicated digital system in a dedicated digital band.

The main reason IBOC is promoted is because a new dedicated digital
band would level the playing field: the present 250-Watt AM
daytimer, once ensconced in the new band, would have just as clear
and clean a signal as the 50-Kw clear channel or the high-power FM
-- just as good fidelity, the same coverage, and 24-hour operation.
Just like your Web site is as clear and as easily accessible as
NBC's.


Didn't the Canadians establish a new digital band? Is it being heard
much?


A dedicated digital band might also be scalable and allow many more
channels for the listener -- hundreds, thousands perhaps. Probably
enough to allow public access (in which anyone can be a broadcaster
for free or nearly free) on an even greater scale than does cable
television or Internet radio.

And that would mean more competition for the big-money men.

And it would mean that competition would now be purely on the basis
of programming, not the sheer signal superiority which the money-men
have paid for.

They want to preserve the _inferiority_ of their smaller
competitors. IBOC does that. They want to maintain the high economic
hurdle to becoming a broadcaster. IBOC does that.



With all good wishes,



--

Kevin Alfred Strom.


Well, maybe, but I don't see the entire broadcast industry rushing to
IBOC. The night time ban puts a big crimp on IBOC. IBOC reduces the
bandwidth and fidelity of the main channel. Also, putting all that
power into sideband noise reduces the power and signal to noise ratio of
the main channel. People who are annoyed by bad sounding AM radio and
have yet to buy an IBOC radio are more likely to tune out.

People who don't much care about fidelity, and I think that's the
majority of casual listeners, won't much care for IBOC, either.

Frank Dresser


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Old February 24th 04, 11:49 PM
Ron Hardin
 
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Frank Dresser wrote:
It's just a noise rush, but not white exactly. The giveaway is that

it's on
only one sideband of the station you're trying to hear. If you hear

it on the
LSB, the offending IBOC station is 10 kHz higher (not lower as you'd

expect);
and if on USB, then 10 kHz lower.


I'm not sure I understand. The spectrum plot shows two symmetrical
peaks off the carrier frequency. The noise I observed was consistant
with that.


It's not symmetric around the adjacent channel station being interfered with.

If IBOC is on 700 and you're listening to 710, the the IBOC noise is at 713,
which is the upper sideband of 710. If you listen to 710 LSB, the noise
disappears.
--
Ron Hardin


On the internet, nobody knows you're a jerk.
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Old February 25th 04, 12:03 AM
Frank Dresser
 
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"Ron Hardin" wrote in message
...

It's not symmetric around the adjacent channel station being

interfered with.


OK. The noise was symmetrical around 720, and I was trying to catch
710.


If IBOC is on 700 and you're listening to 710, the the IBOC noise is

at 713,
which is the upper sideband of 710. If you listen to 710 LSB, the

noise
disappears.
--
Ron Hardin



I live a few miles from WGN's transmitter, and the normal sideband
splatter makes WOR almost unlistenable. I was just curious about
propagation that night. A station ID was all I wanted. If I ever hear
the noise again, I'll listen to it more carefully.

Frank Dresser





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