7 Channels Possible with ALL-DIGITAL Station

[TheRover]

From the Wikipedia Article:

Stations may eventually go all-digital, thus allowing as many as three full-power channels and four low-power channels (seven total). As defined by iBiquity these channels could be sub-divided into:

CD-quality (100 kbit/s)

FM-quality (25-50 kbit/s)

AM-quality (12 kbit/s)

Talk-quality (5 kbit/s)

Alternatively, they could broadcast one single channel at 300 kbit/s.

 

[Play Freebird]

From the Wikipedia Article:

Stations may eventually go all-digital, thus allowing as many as three full-power channels and four low-power channels (seven total).

Thank goodness the leaders of our industry steered us away from Eureka-147 and on to IBOC. Eureka was soundly rejected because it would have flooded each market with new channels, diluting audience share and making it nearly impossible for anyone to turn a profit. This is not a problem with IBOC.

 

[tomservo]

It's not a problem for IBOC either because at this point, it's all theory. We all know that there will likely never be a digital switchover on the radio dial in our lifetimes. Anyway, 5kbps for speech? Surely they're joking. A cursory listen to XM's barker channels shows how unrealistic those bitrates sound! Now two channels at 150kbps? That sounds do-able.

 

[Chuck]

AM-quality (12 kbit/s)

Talk-quality (5 kbit/s)

The curious thing is speech usually sounds worse at low bit rates than music does. That is probably because our brains know what the human voice is supposed to sound like. Music is much more subjective which is why most people accept 64 kbs mp3's as "good enough."

 

[RadeoEngineer]

AM-quality (12 kbit/s)

Talk-quality (5 kbit/s)

The curious thing is speech usually sounds worse at low bit rates than music does. That is probably because our brains know what the human voice is supposed to sound like. Music is much more subjective which is why most people accept 64 kbs mp3's as "good enough."

I would suggest that acceptance of low bit rate audio comes form never having heard high quality analog audio. Those that are used to interpreting the googling, combed, flanged audio of their expensive cell phones think iPods and the like sound just swell.

 

[landtuna]

.... most people accept 64 kbs mp3's as "good enough."

I don't know anyone who "accepts" 64 kbs as "good enough". It sounds like crap. 128 would be my minimum and that only for non-serious music listeners.

And who said 100 was "CD quality"? It is nothing of the sort. CD is 320.

 

[KB1OKL]

I liked radio best when it was LP-quality.

 

[tomservo]

I liked radio best when it was LP-quality.

I've always believed that the best sound quality put out by the mainstream music industry was from about 1977-1984, right before CDs hit the world. Practically every album I have from that era just sounds fantastic. (Even the K-Tel ones, which were roundly criticized back then for being cheap pressings.)

 

[DaveBayArea]

I've always believed that the best sound quality put out by the mainstream music industry was from about 1977-1984, right before CDs hit the world. Practically every album I have from that era just sounds fantastic. (Even the K-Tel ones, which were roundly criticized back then for being cheap pressings.)

It seems like a lot of the music from that era on the bigger labels was hit-and-miss though. There was sometimes distortion in the highs, and the occasional "pop" - even on a brand new record. But if you purchased something on a smaller label - Flying Fish and Rounder immediately come to mind - the quality was astounding. Of course, that was the era of the Mobile Fidelity Sound Labs recordings too, and they were fantastic.

Dave B.

 

[8638]

I liked radio best when it was LP-quality.

I've always believed that the best sound quality put out by the mainstream music industry was from about 1977-1984, right before CDs hit the world. Practically every album I have from that era just sounds fantastic. (Even the K-Tel ones, which were roundly criticized back then for being cheap pressings.)

The LP really hit its stride during that era. I, too, still have LP's, and I still think they sound good.

The discussion about bit rates is interesting. When I toggle back and forth between analog FM broadcasts and XM, the difference is immediately noticeable, with analog FM clearly superior. Humans don't hear digitally, they hear analog, dang it!

 

[Savage]

I've picked up Command and Audio Fidelity LPs, with dogeared cardboard jackets at yard sales for pocket change - and if the records are relatively clean and not badly worn, they're vastly superior to XM-Sirius wonderfully-digital audio. And many CDs in terms of naturalness.

And don't get me started about a comparison with HD Radio audio, particularly if the station has more than one stream operating.

Maybe it's because of my exposure to decades of audio from analog sources. But I find the occasional tick or pop or click from a decently-clean LP, or a little adjacent-channel "monkey chatter" in AM listening, distinctly less objectionable than the flanging, swimming and chorusing I hear in much digital material - on the air or on the web.

Yes: low bitrates do affect the human voice far more noticeably. The human ear is very sensitive to quality in human speech. It's the way our analog-only heads have been designed. Which is another reason why AM-HD is such a miserable failure: the audio quality is inappropriate for the typical AM programming application, primarily spoken-word material. (Even if the interference wasn't horrible.)

 

[ajc_trw]

I liked radio best when it was LP-quality.

I've always believed that the best sound quality put out by the mainstream music industry was from about 1977-1984, right before CDs hit the world. Practically every album I have from that era just sounds fantastic. (Even the K-Tel ones, which were roundly criticized back then for being cheap pressings.)

I have a couple K-Tel records of both kind (Kind one:1 LP with loads of songs and Kind two: 2 LPs with four to five songs per side) and find the quality to be quite high. The one thing I've found is they don't mess with the dynamic range of the original recording.

Now Ronco put out crap. One 20 song album was shameless in fading songs out before their time.

It's a shame K-Tel didn't make the transition into CDs (IIRC). Now THAT'S what I call music.

 

[Chuck]

.... most people accept 64 kbs mp3's as "good enough."

I don't know anyone who "accepts" 64 kbs as "good enough". It sounds like crap. 128 would be my minimum and that only for non-serious music listeners.

And who said 100 was "CD quality"? It is nothing of the sort. CD is 320.

Maybe you and I think that way, but most of the current generation don't think so. It is probably because they've never listened to decent analog audio, which can sound fantastic.

 

[tomservo]

The discussion about bit rates is interesting. When I toggle back and forth between analog FM broadcasts and XM, the difference is immediately noticeable, with analog FM clearly superior. Humans don't hear digitally, they hear analog, dang it!

That's interesting considering how many FM stations these days have something digital in the chain. The music is usually mp3 and it may be re-compressed and sent over a digital STL before reaching the transmitter.

I remember back in the early 90's when the Dick Broadcasting stations in Birmingham made the switch to some type of digital music storage system. The difference in sound quality was immediately noticeable. They basically sounded like a bad HD feed but in analog.

That was pre-mp3 so it may have been MUSICAM or some other proprietary storage format, or a digital STL gone wrong.

A polite call to the engineer got me nowhere, he thought it sounded "exactly the same as before, you must have something wrong with your radio." Exact words. :

These days, in rural Mississippi, every single radio station has something wrong with it, sound-wise. They either sound swishy-watery due to compression, or have balance issues, or have poorly set up processing. Even the Supertalk talk network sounds really terrible.

Just because FM is analog doesn't mean engineers won't find a way to screw it up.

 

[satech]

I remember back in the early 90's when the Dick Broadcasting stations in Birmingham made the switch to some type of digital music storage system. The difference in sound quality was immediately noticeable. They basically sounded like a bad HD feed but in analog.

That was pre-mp3 so it may have been MUSICAM or some other proprietary storage format, or a digital STL gone wrong.

That was probably MP2, or maybe even MP1. Although I didn't know what it was at the time, I first heard digital compression artifacts in 1996 or so, on the on-air feed of the "Radio Aahs" kids format (pre-Radio Disney). To me it just sounded gritty and chattery, as if parts of the audio were getting cut out -- which is essentially how lossy digital compression works.

Then it was only about a year later (1997) when radio commercials started having really bad compression format, as if the ad agencies were sending them to the stations as very low-bitrate MP3 files (which indeed, they were). This continued for about 2-3 years, on all the major market stations, until the quality finally came up to par.

 

[Ai4i]

The most significant advantage of digital is its infinite s/n ratio.
No digital radio will ever go "psst" and the thousandth play of a CD will sound as good as the first.

 

[audioguy]

Hello, people... the S/N ratio of a digital signal is not infinite. It is dependent upon the bit depth.

 

[Play Freebird]

No digital radio will ever go "psst" and the thousandth play of a CD will sound as good as the first.

The way some CDs are mastered today, you should have said "the thousandth play will sound as bad as the first".

To illustrate, here's a waveform sample from "Because of You" by Kelly Clarkson - courtesy of satech:

http://i42.tinypic.com/28157xw.gif

Interesting discussion on a way to fix this damage:

http://boards.radio-info.com/smf/index.php?topic=166455.0

Needless to say, running clipped audio into a lossy codec (aka HD Radio) is just asking for trouble.

 

[Ai4i]

"the thousandth play will sound as bad as the first"

We sit correctedly, just not the new music to which we listen.

 

[K6JHU]

Dynamic range and S/N on digital is already past what we can hear.

My LP's sound better than a CD after I have digitized them and removed the scratches and pops. So it is not the digital. It seems to be mostly the lousy engineering that is done on the audio nowadays.