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HD on AM

S

strangelove

Guest
So far there are only three AM stations in Miami/Ft. Lauderdale that are using IBOC and truth be told I'm not overly impressed. They claim the quality is on par with FM and while it's much clearer in comparison to analog AM I've found it to be more akin to a so-so sounding webstream (complete with tinny artifacts) that's completely stripped of the warmth and richness of an FM broadcast. Is this as good as it gets or do these stations just have lousy processing?
 
Well one little thing is that those sparkling highs your hearing are synthesized, some call them downright shrill, that should tell you something right there.
 
strangelove said:
So far there are only three AM stations in Miami/Ft. Lauderdale that are using IBOC and truth be told I'm not overly impressed. They claim the quality is on par with FM and while it's much clearer in comparison to analog AM I've found it to be more akin to a so-so sounding webstream (complete with tinny artifacts) that's completely stripped of the warmth and richness of an FM broadcast. Is this as good as it gets or do these stations just have lousy processing?
Click to expand...

Sorry strangelove, but chances are that's as good as it gets. The whole AM = FM, FM = CD thing is just marketing hype; the bitrate allocated to the digital stream is just too low to be artifact free. :(
 
strangelove said:
So far there are only three AM stations in Miami/Ft. Lauderdale that are using IBOC and truth be told I'm not overly impressed. They claim the quality is on par with FM and while it's much clearer in comparison to analog AM I've found it to be more akin to a so-so sounding webstream (complete with tinny artifacts) that's completely stripped of the warmth and richness of an FM broadcast. Is this as good as it gets or do these stations just have lousy processing?
Click to expand...

I have no connection with Meduci besides being a satisfied customer but I've been listening to CHWO (former call letters) on 740 from Toronto here in MA at night with my AMX-2000 with a C Crane Twin Coil Ferrite loop receiver run through a Marantz 2385 and this is what AM can sound like. It sounds great, not sure how wideband CHWO is but the sound is inviting to the ears not fatiguing like the ahem... FM-like quality of AM IBOC ::)
 
Zach said:

Sorry strangelove, but chances are that's as good as it gets. The whole AM = FM, FM = CD thing is just marketing hype; the bitrate allocated to the digital stream is just too low to be artifact free. :(
Click to expand...

Bummer. I hate to sound snobbish but I was expecting better.
 
strangelove said:
Bummer. I hate to sound snobbish but I was expecting better.
Click to expand...

You're not being snobbish at all -- you're simply asking that the truth be told, as we all should.

Keep in mind also that the AM IBOC encoder generates both a "core" stream and an "enhanced" stream. The core stream is easier to decode, but only carries mono audio content. You would need to be in a very strong AM signal area to decode the "enhanced" stream, which adds the stereo information. This is because the enhanced stream relies on the secondary and tertiary sideband groups, which are much lower in power than the primary sidebands placed out at the edge of the first-adjacent channels.

For a technical discussion and some diagrams showing how IBOC causes interference, see this article starting on Page 4:

http://www.e-e.idv.tw/radio/IBOC-AM.pdf

In a way, this "core" and "enhanced" principle is similar to the FM stereo blending feature incorporated into most current analog receivers. However, Sony has found a way to greatly improve FM stereo performance in their new XDR-F1HD tuner, which practically eliminates the coverage penalty. The analog FM stereo quality of the Sony clearly beats AM IBOC hands down.

Hopefully, this technology will carry over to the designs of other manufacturers.
 
strangelove said:
So far there are only three AM stations in Miami/Ft. Lauderdale that are using IBOC and truth be told I'm not overly impressed. They claim the quality is on par with FM and while it's much clearer in comparison to analog AM I've found it to be more akin to a so-so sounding webstream (complete with tinny artifacts) that's completely stripped of the warmth and richness of an FM broadcast. Is this as good as it gets or do these stations just have lousy processing?
Click to expand...

That's the impression I got - IBOC sounded like a low bitrate 20 or 32Kbps Windows Media or AAC+ stream.

But Ibiquity and HD broadcasters don't care because they're betting most people will be listening with cheap radios or in the Car/SUV where road noise or the heater/AC will cover those artifacts up.
 
One more example of how impossible it is, to reconcile the preposterous claims made for HD Radio by its proponents (which are increasingly a lonely, shrinking and ignored minority.)

Let's try to get this straight:

a. AM's woes are due to "lousy sound quality." So: we'll introduce IBOC, which.....
b. Necessitates reducing analog bandwidth, thus making AM sound even WORSE for 99% of existing listeners....
 
...bizarre. Did iBiquity design this posting software?? Does anybody else have this auto-posting problem??

Anyway:

c. So we can have digital HD, But the codec's low bitrate and synthesis of all audio above 4.5 kHz makes the digital signal sound gritty, tinny and fatiguing, but....
d. It's okay because nobody will notice the lousy audio because they all listen in noisy environments.

Whaaaat? :p

But: wait!! It gets better!

We need to improve AM reception, so "HD is the answer." But skywave interference will prevent detection of the digital signal in many, if not most listening conditions, unless the listener is located in a noise-free high-intensity field of the received station. Under which conditions, the radio reverts to analog. But the analog will be highly compromised by arriving IBOC hash on adjacent frequencies...and self-interference from the originating station as well, resulting in a massively increased noise floor.

The world of HD Radio is a surreal vortex of lies, self-defeating self-interested inside dealing, bad management, junk engineering, and sheer, utter, palpable stupidity.
 
You would have to have 30KHz channel spacing to have half a chance of HD-AM working - during the day - at night all bets are off.
Better analog AM receivers with software for noise reduction is the answer, and compelling niche programming, not HD-AM.
 
JohnnyElectron said:
You would have to have 30KHz channel spacing to have half a chance of HD-AM working - during the day - at night all bets are off.
Better analog AM receivers with software for noise reduction is the answer, and compelling niche programming, not HD-AM.
Click to expand...

Or in other words: That's all she wrote folks. Goodnight Irene.
 
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