[BC] IBOC AM Quality

Mike McCarthy Towers
Fri Mar 23 06:34:20 CDT 2007


Think of IBOC as being another bit reduction iteration in a long chain of 
data compression/reducing algorithms. If you can send 384Kbps or better 
audio from origination to the IBOC encoder, you should air fairly decent 
sounding audio.  If you play upconverrted IPOD cuts or some of the other 
crap which is sent to stations through a compressed automation or satellite 
system followed by a compressed STL, your signal will sound degraded.

No different than FM.  But more obvious since the data stream is only 
24Kbps and will reveal upstream bit reduction more profoundly.

MM

At 09:09 PM 3/22/2007 -0400, James Kuzman wrote
>The new night-time AM IBOC decision notwithstanding...
>
>I have to take a bit of issue with those who say that AM IBOC audio 
>quality isn't substantially better than the analog.
>
>Is it FM quality?  No, even though the promos we hear daily tell us it is; 
>does it bring new life to music on the AM band?  Absolutely.  I realize 
>that most AM stations have been resigned to carry sports, news, and talk 
>where the benefits of improved audio would be negligible, but for music - 
>the audio quality is significantly better.
>
>It takes some work, mind you, to make it sound decent... it's not 
>perfect... some material sounds "like satellite," as someone pointed out - 
>referring I'm guessing to the encoding and compression artifacts (data, 
>not audio); and it does reveal bad source material very quickly.
>
>All of that being said, however, if you feed quality audio in, and process 
>carefully - by which I mean keeping the sound open, not dense, and being 
>careful about how you handle the high bands - AM IBOC can sound quite nice.
>
>Jim Kuzman
>WDYZ AM 990, Orlando



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