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Radio processing



 
 
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  #1  
Old May 19th 20, 05:59 PM posted to rec.audio.pro
Tatonik
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Posts: 21
Default Radio processing


Yesterday flooding in the Chicago area knocked out power to the Willis
Tower (née Sears Tower) atop which the broadcast antenna for WFMT 98.7
FM sits, a station I have been in the habit of listening to. There was
static the whole day. This morning it was back on the air with the help
of WBEZ, broadcasting from the top of the John Hancock building. The
only difference is that now WFMT sounds nasty and tizzy, almost like
it's clipping. I assume everything is being run through WBEZ's
processing chain.

As best I can tell through a few minutes of listening, the WFMT internet
stream is unaffected by the sound changes in the analog broadcast.

WFMT is a classical station and WBEZ is a public radio news and talk
station (used to have some jazz, but not anymore). I'm surprised there
would be such a dramatic difference between stations.

What kinds of things are some of these stations likely doing to the
audio and why?

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  #2  
Old May 19th 20, 06:17 PM posted to rec.audio.pro
John Williamson
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Posts: 1,689
Default Radio processing

On 19/05/2020 17:59, Tatonik wrote:

> As best I can tell through a few minutes of listening, the WFMT internet
> stream is unaffected by the sound changes in the analog broadcast.
>
> WFMT is a classical station and WBEZ is a public radio news and talk
> station (used to have some jazz, but not anymore). I'm surprised there
> would be such a dramatic difference between stations.
>
> What kinds of things are some of these stations likely doing to the
> audio and why?
>

There is normally an audio "optimiser" in the feed to the transmitter,
doing things like tailoring the frequency profile of the transmitted
material so all the music comes out sounding similar, and compressing
the signal to make it more pleasant to listen to in fringe areas, with
fewer surprises as levels change between tracks or other audio segments.

Basically a multiband compressor.

There is an independent feed to the streaming server, which tends to be
closer to what is in the source feed.

This is one very popular make of optimiser.

https://www.orban.com/radio-audio-processors

--
Tciao for Now!

John.
  #3  
Old May 19th 20, 08:36 PM posted to rec.audio.pro
Scott Dorsey
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Posts: 16,712
Default Radio processing

Tatonik > wrote:
>Yesterday flooding in the Chicago area knocked out power to the Willis
>Tower (née Sears Tower) atop which the broadcast antenna for WFMT 98.7
>FM sits, a station I have been in the habit of listening to. There was
>static the whole day. This morning it was back on the air with the help
>of WBEZ, broadcasting from the top of the John Hancock building. The
>only difference is that now WFMT sounds nasty and tizzy, almost like
>it's clipping. I assume everything is being run through WBEZ's
>processing chain.


My first guess is that they are getting the audio over to the other site
through some lossy-compressed mechanism. If they have internet codecs
used for live remotes, that would be the first way I'd do it. Nobody has
isdn lines around anymore.

The processing chain is the least of your worries.

>What kinds of things are some of these stations likely doing to the
>audio and why?


They could tell you but they'd have to kill you.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."
  #4  
Old May 20th 20, 12:03 PM posted to rec.audio.pro
[email protected]
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Posts: 1,729
Default Radio processing

Scott Dorsey wrote:

>My first guess is that they are getting the audio over to the
>other site through some lossy-compressed mechanism.
>If they have internet codecs used for live remotes, that would
>be the first way I'd do it. Nobody has isdn lines around anymore.


>The processing chain is the least of your worries.

_________

Lossy-data reduction does not cause "nasty and tizzy" effects, as the original poster referred to.

Questionable processing chain settings, as JW mentioned, or less than ideal gain-staging, can.
  #6  
Old May 20th 20, 02:35 PM posted to rec.audio.pro
Don Pearce[_3_]
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Posts: 2,319
Default Radio processing

On Wed, 20 May 2020 14:15:19 +0100, John Williamson
> wrote:

>On 20/05/2020 12:03, wrote:
>
>> Lossy-data reduction does not cause "nasty and tizzy" effects, as the original poster referred to.
>>
>> Questionable processing chain settings, as JW mentioned, or less than ideal gain-staging, can.
>>

>Lossy data compression and digital transmission can and does cause many
>artifacts, including "nasty and tizzy" ones as well as burbling mud and
>other problems when the error correction fails.
>
>I hear these all the time as I travel round using a DAB radio.
>
>If you must criticise, at least do so correctly.


Haven't heard burbling mud for many years. I used to get it often on
my Arcam home tuner, but I think that was their first effort, and it
had a lousy front end. Anyway, the mud is what you got when you were
running out of signal. I guess these days they just drop the audio
before error correction is denied signal to that level. All still
better than FM though. The slightest multipath, inevitable in urban
driving, resulted in swishes and hisses. I used to inch back and forth
in traffic jams to find an exact location where the signal was clean.
DAB relished multipath - it just meant more signal.

d

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  #7  
Old May 20th 20, 02:46 PM posted to rec.audio.pro
John Williamson
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Posts: 1,689
Default Radio processing

On 20/05/2020 14:35, Don Pearce wrote:

> Haven't heard burbling mud for many years. I used to get it often on
> my Arcam home tuner, but I think that was their first effort, and it
> had a lousy front end.


Just lately, I have been driving a bus without a radio fitted, so have
been driving round using a cheap portable one sitting on the dash, which
still does the burbling mud just before it mutes.

FM would be better, possibly, as the degradation is easier to live with,
but only on the news station I usually listen to. Music or drama are
non-starters on either system


--
Tciao for Now!

John.
  #8  
Old May 20th 20, 03:14 PM posted to rec.audio.pro
Don Pearce[_3_]
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Posts: 2,319
Default Radio processing

On Wed, 20 May 2020 14:46:39 +0100, John Williamson
> wrote:

>On 20/05/2020 14:35, Don Pearce wrote:
>
>> Haven't heard burbling mud for many years. I used to get it often on
>> my Arcam home tuner, but I think that was their first effort, and it
>> had a lousy front end.

>
>Just lately, I have been driving a bus without a radio fitted, so have
>been driving round using a cheap portable one sitting on the dash, which
>still does the burbling mud just before it mutes.
>
>FM would be better, possibly, as the degradation is easier to live with,
>but only on the news station I usually listen to. Music or drama are
>non-starters on either system


Here in the London area DAB is rock solid. It is even piped into the
3/4 mile Hatfield Tunnel. FM stands no chance in there.

d

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  #9  
Old May 20th 20, 03:52 PM posted to rec.audio.pro
John Williamson
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Posts: 1,689
Default Radio processing

On 20/05/2020 15:14, Don Pearce wrote:
> Here in the London area DAB is rock solid. It is even piped into the
> 3/4 mile Hatfield Tunnel. FM stands no chance in there.
>

I've been driving round Surrey, not far from Guildford.

--
Tciao for Now!

John.
  #10  
Old May 20th 20, 07:14 PM posted to rec.audio.pro
[email protected]
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Posts: 1,729
Default Radio processing

John Williamson wrote:

>Lossy data compression and digital transmission can and
>does cause many artifacts, including "nasty and tizzy" ones
>as well as burbling mud and other problems when the error
>correction fails.


>I hear these all the time as I travel round using a DAB radio.


>If you must criticise, at least do so correctly.


________

By now you should know where I'm coming from in that regard, lol! Formats have
evolved to the point where there is usually less degradation or undesirable
qualities from the formats themselves than from processing choices in production,
post, and in the case of radio(analog or DAB): the transmission chain.
 




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