is it likely many stations will air programming on HD3 or will it be enough work for them to offer it on HD2?
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HD2 / HD3
- Thread starter Clayton Douglas
- Start date
R
Radioman100
Guest
Clayton Douglas said:is it likely many stations will air programming on HD3 or will it be enough work for them to offer it on HD2?
It's not so much a matter of work, it's a matter of bandwidth. With HD Radio you get a certain amount of digital "pie." The more ways you cut it, the less you have for each channel. You can divide it pretty much any way you want, but most stations are opting to stop at HD2 for now.
Each HD station has the ability to split the digital signal 8 different ways. If the analog signal ever goes away completely, this might make some sense, otherwise I expect most stations to continue operating just one or two digital channels with a few opting to offer a 3rd low bitrate channel.
If you're asking if its worth it or not, I think a lot of that will depend on market size and the competitive situation the station is in.
How low of a bitrate can they crank down the HD3 and still make it listenable for voice?
I'm thinking of adding NOAA Weather Radio as an HD3 channel on the FMs - so how much is the minimal for a usuable HD3?
I'm thinking of adding NOAA Weather Radio as an HD3 channel on the FMs - so how much is the minimal for a usuable HD3?
Hw mch dta ca yu thw awy nd till dcod the nfrmtn ?
I abhor schemes where the original premise is " What's the least we can do to get by?"
The full 96k stream is roughly equivalent to the FM analog in resolution. 48k is hardly worth the energy to power up a radio.
Three 32k streams is just data, not capable of suffcient audio quality for radio broadcast.
This rate is acceptable for a voice box in a talking child's toy, but embarrassing to hear over the air.
I abhor schemes where the original premise is " What's the least we can do to get by?"
The full 96k stream is roughly equivalent to the FM analog in resolution. 48k is hardly worth the energy to power up a radio.
Three 32k streams is just data, not capable of suffcient audio quality for radio broadcast.
This rate is acceptable for a voice box in a talking child's toy, but embarrassing to hear over the air.
M
Mike Walker
Guest
Tom has spoken, it must be true. Only it isn't. 48kbps sounds better than most analog FM under typical conditions (in stereo), and 32kbps or lower sounds just fine for mono programs like news. Plus there's expanded-hybrid mode, now available, which makes it possible to broadcast three streams, AND keep bitrates above 48kbps.
96kbps is far from 'the same resolution as analog FM'. In fact the signal to noise ratio is as much as 30-40db greater, so the background is dead quiet. There is no pre-emphasis curve, so it's possible to have full modulation AND crystal-clear highs...not so with analog FM which may be loud, or bright, but never both. Distortion is orders of magnitude lower than what is typical for analog FM stereo. And channel separation is nearly infinite.
One station in my area, WFAE in Charlotte, has HD3. The HD1 (talk/news from NPR and local) sounds very good. The HD2 (adult alternative/eclectic music) is very good as well, with few audible artifacts...and then only if you're straining to hear them. The HD3, on the other hand, with BBC World Service, is, charitably, stinky. Remember how internet radio sounded a decade ago, when everyone was on dialup? Kind of like that. You can listen if there's something you REALLY want to hear. If you're used to the BBC on shortwave, then you might find this better...by a tiny margin. I consider it less listenable than typical analog AM, and by a good margin.
So far, that's my only HD3 experience. I have no idea how the bits are divided among streams, or how much of the limitation on their HD3 is the fault of the source, vs. the low bitrate. I just know that while HD1 and 2 sound just fine, HD3, er, doesn't.
96kbps is far from 'the same resolution as analog FM'. In fact the signal to noise ratio is as much as 30-40db greater, so the background is dead quiet. There is no pre-emphasis curve, so it's possible to have full modulation AND crystal-clear highs...not so with analog FM which may be loud, or bright, but never both. Distortion is orders of magnitude lower than what is typical for analog FM stereo. And channel separation is nearly infinite.
One station in my area, WFAE in Charlotte, has HD3. The HD1 (talk/news from NPR and local) sounds very good. The HD2 (adult alternative/eclectic music) is very good as well, with few audible artifacts...and then only if you're straining to hear them. The HD3, on the other hand, with BBC World Service, is, charitably, stinky. Remember how internet radio sounded a decade ago, when everyone was on dialup? Kind of like that. You can listen if there's something you REALLY want to hear. If you're used to the BBC on shortwave, then you might find this better...by a tiny margin. I consider it less listenable than typical analog AM, and by a good margin.
So far, that's my only HD3 experience. I have no idea how the bits are divided among streams, or how much of the limitation on their HD3 is the fault of the source, vs. the low bitrate. I just know that while HD1 and 2 sound just fine, HD3, er, doesn't.
Yes, the S/N is 40 db higher. I was pointing out that the analog at least does not suffer from sounding like it was reconstituted from chunks, no matter how small. I prefer audio sounding fluid, continuous and smooth. I will always prefer the sample offering the most data available, even with extraneous noises added. My brain does a fine job of signal processing, but then I live in a
metro signal area.
The distortion in weak FM signals is annoying enough that for many people, I'll go along with you that the FM HD is probably better sounding.
As an engineer, it is my job to assess technology and applications.
I have a much harder time accepting something which causes me to wonder where in the airchain the under-biased transistor is.
If you can't give me full 20khz resolution full time, I do not want to hear higher frequencies bursting forth in fits and starts.
Nothing in the real world sounds like that, except music which started out in digital to begin with.
Do you prefer a high quality silver photograph, or a medium resolution digital ink-jet photo of a large format Ansel Adams print?
Remember, the digital has no degradation, but the analog has 10,000 times more data.
Would you make the same choice if you were publicly displaying the print?
Would you present the cheaper, easier choice, or pay the money for a full continuous gray -scale silver print?
I argue that quick and easy digital could be good enough, were we willing to move enough data.
If we're not ready to move that much data, back off until it's at least equal to the previous tech.
No one is served by relaxing standards and telling the customers to get used to the degraded result.
And to those who can't hear the degradation, have you ever tried to watch a movie where the projector wasn't focused, and everybody in the theatre starts hollering?
Back in the days of human projectionists you had to hire someone who could tell the difference and properly focus the projector.
Once we get to point that everyone thinks radio should sound like a keychain pocket memo recorder, this won't be a problem.
But right now, too many people know radio need not sound gravelly, zingy, swirly or zizzly.
Such by-products only occur as transients in overtones in normally produced audio, and in those instances, they define sharpness
and high energy events. Having these these strange harmonics added to instrument voices which normally have no such harmonics
is NOT high fidelity.
32k and 48k streams are adequate to convey the data in a 300-3000 hz landline because there isn't anything that can happen any faster that they can describe it. Once you start trying to feed high frequency data to a slow stream, the lack of resolution is immediately evident to those who can tell what they're listening to. The only way to make it acceptable is to limit the high-frequency decoded result back down to a level where the sinewaves aren't audibly stair-stepped.
Speaking of shortwave, I far prefer the BBC (at least what it used to sound like) on SW to their net feed.
Same reason.
metro signal area.
The distortion in weak FM signals is annoying enough that for many people, I'll go along with you that the FM HD is probably better sounding.
As an engineer, it is my job to assess technology and applications.
I have a much harder time accepting something which causes me to wonder where in the airchain the under-biased transistor is.
If you can't give me full 20khz resolution full time, I do not want to hear higher frequencies bursting forth in fits and starts.
Nothing in the real world sounds like that, except music which started out in digital to begin with.
Do you prefer a high quality silver photograph, or a medium resolution digital ink-jet photo of a large format Ansel Adams print?
Remember, the digital has no degradation, but the analog has 10,000 times more data.
Would you make the same choice if you were publicly displaying the print?
Would you present the cheaper, easier choice, or pay the money for a full continuous gray -scale silver print?
I argue that quick and easy digital could be good enough, were we willing to move enough data.
If we're not ready to move that much data, back off until it's at least equal to the previous tech.
No one is served by relaxing standards and telling the customers to get used to the degraded result.
And to those who can't hear the degradation, have you ever tried to watch a movie where the projector wasn't focused, and everybody in the theatre starts hollering?
Back in the days of human projectionists you had to hire someone who could tell the difference and properly focus the projector.
Once we get to point that everyone thinks radio should sound like a keychain pocket memo recorder, this won't be a problem.
But right now, too many people know radio need not sound gravelly, zingy, swirly or zizzly.
Such by-products only occur as transients in overtones in normally produced audio, and in those instances, they define sharpness
and high energy events. Having these these strange harmonics added to instrument voices which normally have no such harmonics
is NOT high fidelity.
32k and 48k streams are adequate to convey the data in a 300-3000 hz landline because there isn't anything that can happen any faster that they can describe it. Once you start trying to feed high frequency data to a slow stream, the lack of resolution is immediately evident to those who can tell what they're listening to. The only way to make it acceptable is to limit the high-frequency decoded result back down to a level where the sinewaves aren't audibly stair-stepped.
Speaking of shortwave, I far prefer the BBC (at least what it used to sound like) on SW to their net feed.
Same reason.
Amen Tom!
R
Radioman100
Guest
To each his own. I recommend people listen to it themselves and make a decision then.
To me personally, 48k HD sounds great. As good as analog FM and significantly better than satellite radio. It's different, as each has its own positive qualities. HD at 48k offers better highs than analog FM by far, but its at the expense of slight distortion in the midrange on tracks that have a lot of midrange energy. (Think screaming electric guitar.)
Analog purists have been decrying digital audio for decades. If you generally prefer CDs or MP3s to analog records, then HD Radio may just be for you.
To me personally, 48k HD sounds great. As good as analog FM and significantly better than satellite radio. It's different, as each has its own positive qualities. HD at 48k offers better highs than analog FM by far, but its at the expense of slight distortion in the midrange on tracks that have a lot of midrange energy. (Think screaming electric guitar.)
Analog purists have been decrying digital audio for decades. If you generally prefer CDs or MP3s to analog records, then HD Radio may just be for you.
I am not sure how the bitrates are divided for each of the 3 HD streams for 105.1 WOJO-FM Evanston-Chicago, but all three streams sound better than I would expect. The first two run music, and the third one sometimes has music, sometimes talk. The HD3 stream is a simulcast of 1200 WRTO (AM) Chicago. WOJO-HD3 sounds significantly better than WRTO, even compared to the HD-AM signal from that station, when I can actually get it. The HD3 feed has an additional advantage of being available day or night -- It doesn't get obliterated by WOAI San Antonio like WRTO does.
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