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AM HD TURNOFF PACE ACCELERATES

satech said:
IBOC exciters are really just computers running Linux. They certainly could be reprogrammed to transmit C-Quam AM Stereo, if iBiquity would allow it. Motorola's 25-year patent on C-Quam has expired, so it is free for anyone to use. And considering that many HD Radio receivers decode C-Quam, it would certainly make sense for stations with disused AM IBOC equipment to take advantage of that capability.
Click to expand...
Since Kahn is expired, they could now use that system.

Jeff in Sa-ra-so-ta!
 
N1WVQ said:
I wonder how ISB would work on S.W.. I wonder if any hams are using it. I know of one using C-QuAM.
Click to expand...

Probably not that good, because especially on SW you get quite a bit of selective fading and that means that the two sidebands are affected differently. You could probably get some stereo effect but it would be like listening to a phlanger.
 
It's funny that I was trying to explain HD radio to my uncle(trying being the key word both with HD and uncle ;).

He popped up with a question that interested me. When I explained that hd on the FM band could allow for sub-channels, like digital tv can. It is not the same, it was the best I could think of to explain it.

I answered this next question with a no, to my knowledge it is not possible, could you in anyway play with an AM signal to allow any type of subchannel or "second channel" on the AM band?

As I said I answered no, to the best of my knowledge it can't be done, I did want to ask and see if it has ever been tried, or if anyone ever thought about it.

It got me thinking. Would it be possible by using the two-radio version of AM stereo or some variation of it?

This is totally impracticle and I could not see it happening, is it possible though, that a station could send a signal out that could be decoded on an AM radio with seperate volume control for left/right speakers, and have one program on the left speaker and one on the right?

Of course even if it could, most radios would sound a "bit" messed up :-]. It is just something that is spinning in the big space between my ears since my conversation.
 
GB2Nashville: the Kahn ISB AM Stereo system was in that mode: you could use to radios, one tuned-up and one tuned-down from the center carrier to get AM Stereo until you could buy them in the stores. I tried it, but you got distortion as you got off of the main carrier; I have a cassette of it somewhere when they interviewed THE Leonard R. Kahn about his system just put into place at that station.
 
JohnnyElectron said:
GB2Nashville: the Kahn ISB AM Stereo system was in that mode: you could use to radios, one tuned-up and one tuned-down from the center carrier to get AM Stereo until you could buy them in the stores. I tried it, but you got distortion as you got off of the main carrier; I have a cassette of it somewhere when they interviewed THE Leonard R. Kahn about his system just put into place at that station.
Click to expand...
Yes Johnny it was the Kahn system, I did the same as you, I guess it did work to a point it was not something that very good though.
 
Going back to Nashville said:
It's funny that I was trying to explain HD radio to my uncle(trying being the key word both with HD and uncle ;).

He popped up with a question that interested me. When I explained that hd on the FM band could allow for sub-channels, like digital tv can. It is not the same, it was the best I could think of to explain it.

I answered this next question with a no, to my knowledge it is not possible, could you in anyway play with an AM signal to allow any type of subchannel or "second channel" on the AM band?

As I said I answered no, to the best of my knowledge it can't be done, I did want to ask and see if it has ever been tried, or if anyone ever thought about it.

It got me thinking. Would it be possible by using the two-radio version of AM stereo or some variation of it?

This is totally impracticle and I could not see it happening, is it possible though, that a station could send a signal out that could be decoded on an AM radio with seperate volume control for left/right speakers, and have one program on the left speaker and one on the right?

Of course even if it could, most radios would sound a "bit" messed up :-]. It is just something that is spinning in the big space between my ears since my conversation.
Click to expand...

You had it right. HDTV and HD radio can both divide the data stream into separate "subchannels" of data. MW HD just has a 20kHz channel and is only able to provide enough bits for one quality audio stream at this time.

NRSC-5-C now provides for SSB operation with IBOC. My current understanding is that the information in both sidebands is identical and redundant for reception in adverse conditions. Sidebands can also be independently lowered as much as 10% to help alleviate adjacent channel interference. [WORD TO THE WISE: The less you toy with the sidebands, the better your life becomes!!!]

A MW or FM IBOC station could conceivably double the number of digital channels it can broadcast by running different, independent channels on each sideband. A HDTV station cannot do this because it only has one "real" sideband! If such activity is feasible I am sure that the NRSC will issue a set of normatives advising us on best ways to exploit this. The BIG puppy was converting to SSB. From now on most future changes for IBOC consist of software mods (LTE) and realistic power increases.

-
 
There is no reason at all why an AM with HD couldn't have a completely "different" program in the digital data.

The fact that the timing is frequently off between the two proves the point.

If the program were totally different it might be jarring at first to listeners, but if it were useful, they'd accept it.

I'm still having a hard time getting used to the slow data accquisition time needed for decode each time a modern TV
is changed to a new channel. It's only a second or two, but NTSC was live in real-time, and I'll
probably always be annoyed by this additional amount of time wasted.

I'd have an easy time with waiting for subchannels, if only the "main" channel decoded in real time.
Naturally, that's impossible since the "waiting time" is exactly the amount of time needed to sync on decode and get one full
frame, regardless of number assignments or which one is the "main" channel.

AM has been a little easier on the ears here in Chicago. The nastiest nearby AM hiss thrower is 620 WTMJ.
There are one or two left here in town that still use the proprietary system, like someone determined to
get use and full wear out of a baggy beige corduroy leisure suit many years after it had become a joke.
 
Tom Wells said:
There is no reason at all why an AM with HD couldn't have a completely "different" program in the digital data.

The fact that the timing is frequently off between the two proves the point.

If the program were totally different it might be jarring at first to listeners, but if it were useful, they'd accept it.
Click to expand...
Sorry, Tom, but there is not a chance that would work. Any little interference, noise, etc., and you are listening to the analogue signal. Just as the counting of pulses was too tight for real world C-quAM.

I have a Visteon Jump in my car, I have tested it all around the town over the last couple of years. As far as an HD radio, it is the one I would recommend - and highly! But the system, itself, is flawed.

It is possible for the RBDS to indicate call letters from one HD FM station while listening to another station. It is also possible for it not to see an in-car FM modulator because of the nearby HD station, as well. On AM, the volume difference switching between analogue and digital is a lot.

Radio is easy. Just turn it on with one button, change the station with another button. To ask somebody to change the balance control to the left or right to hear the intended, but separate, information is too much to ask. On the new radios it is probably hidden in the sub-menus, anyway, so there are more steps. At that point they are looking for the iPod.

Jeff in Sa-ra-so-ta!
 
I meant it would work if the system actually could and did stay locked on the digital decode.
 
Tom Wells said:
I meant it would work if the system actually could and did stay locked on the digital decode.
Click to expand...
"If".

Unfortunately, it doesn't, and there doesn't appear the interest in correcting it.

Jeff in Sa-ra-so-ta!
 
iyiyi said:
NRSC-5-C now provides for SSB operation with IBOC. My current understanding is that the information in both sidebands is identical and redundant for reception in adverse conditions. Sidebands can also be independently lowered as much as 10% to help alleviate adjacent channel interference.
Click to expand...
There is also a new "reduced digital bandwidth" mode which eliminates the secondary and tertiary digital sidebands, allowing an AM HD station to transmit up to 9.4 kHz bandwidth analog audio (not sure why they chose 9.4 instead of the full 10 kHz?). The stated purpose of this is to eliminate self-interference to the station's own audio (that dreaded background hiss that is especially bad in dirctional array nulls) and to reduce adjacent channel interference to neighboring stations on the dial, as well as to allow for the extended audio bandwidth (although iBiquity still recommends resticting the audio to 5 kHz).

That's all well and good for analog listeners, but I can only imagine how bad that "reduced digital bandwidth" HD digital audio sounds, considering how poor regular AM HD sounds already. Can you say "cell phone quality"??
 
WBZ has a meat grinder-diesal motor effect in the background when I listen to it, I'm not sure if this is from it's own IBOC signal generating self interference or KDKA's IBOC interfering with WBZ or maybe WINS's IBOC harmonizing dissonantly with WBZ or All three IBOC'ers hashing all over each other. I suspect it's self interference though as it's more predominent during the day time. Whatever the problem is it ain't pretty.
 
Mason and Glynn Walden, the mad scientist of IBOC, are both big cheese executives with CBS who held similar posts at iBiquity before coming over to The Eye. They probably own large chunks of stock as part of their exit packages from HD-land, so they'll never nix IBOC at CBS no matter how oblivious the market is to it.
 
Savage said:
Mason and Glynn Walden, the mad scientist of IBOC, are both big cheese executives with CBS who held similar posts at iBiquity before coming over to The Eye. They probably own large chunks of stock as part of their exit packages from HD-land,
Click to expand...

The story is that both left because Ibiquity did not have the funds to pay them...
 
Wasn't Walden part of the bloodletting after the codec-swap debacle in 2003, over which the NRSC (temporarily) suspended its standard-setting work?

Mason's trajectory (Infinity/iBiquity/CBS) is a great example of how things can appear to be incestuous.
 
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