Tones passing through lossy compression codecs?

[gunterm]

Syndicating through the internet is cheap and easy, most of the time very reliable. But the downside I've run into is I have to board op the show by hand. I found a free tone detector program that can send commands to my automation software but here's my question: do the subaudible tones that satellite providers use pass through using MP3 at 128kbps mono or other bitrates for that matter? Also what are the common agreed on tones that satellite uses?

 

[RolfTaylor]

Yes, sub audible tones will work with virtually all codecs.

About the only case I have seen where they did not work was a CCITT compliant G.722 that hadn't been tweaked at the low end for better bass. I don't recall off hand what the low end cut off is, but the CCITT complaint version doe snot go as low as most codecs.

The manufacturer in question rapidly fixed this and then it worked.

So, you should be good to go.

As far as the tones, every network has uses them differently. Even more important than frequency, is level.

Best of luck.

Rolf Taylor

Applications/Support Engineer

APT North America

 

[busyradioguy]

There is an afterlife for Mr. 25 Hz! 8)

 

[The Beave]

If I remember correctly the most commonly used tones are 25 hz and 35 hz. There are a few that will pick them up.. I think you need 320/24b/96000 mp3 to consistantly pull it off consistantly with every brand out there.

 

[LA_Guy]

If I remember correctly the most commonly used tones are 25 hz and 35 hz. There are a few that will pick them up.. I think you need 320/24b/96000 mp3 to consistantly pull it off consistantly with every brand out there.

That's not true. Lots of networks send 25 and 35 Hz tones through Starguide every day-and they work just fine. Starguide isn't even close to the quality you claim is necessary.

 

[The Beave]

That's not true. Lots of networks send 25 and 35 Hz tones through Starguide every day-and they work just fine. Starguide isn't even close to the quality you claim is necessary.

Let me clarify myself - some codecs (PC) will simply not hit on 96/44.1/16bit (sub FM quality)
Starguide I have no recollection of their qiality but I remember that Starguide had an external codec for a while then upgraded to ??? When I last looked at the satellite situ. You needed a 128 mp3 codec that was atleast CD quality.

Today you may not, the last time I looked at this it was 2002. when everything was 48/44.1/8 bit (FM/ringtone quality)

 

[dtube1]

An NCE I take care of carries Beethoven Satellite Network. They are distributed through NPR's PRSS and only recently quit using 25hz tones. That station has an Aphex Mk2020 on-air that I have pushing a fair amount of low-bass through (and it sounds amazing on the 1812 Overture!). Anyway, I would be driving around and a 25hz tone would hit: my left leg, which is usually leaning against the door speaker in my Impala, would vibrate 8)
-D

 

[busyradioguy]

An NCE I take care of carries Beethoven Satellite Network. They are distributed through NPR's PRSS and only recently quit using 25hz tones. That station has an Aphex Mk2020 on-air that I have pushing a fair amount of low-bass through (and it sounds amazing on the 1812 Overture!). Anyway, I would be driving around and a 25hz tone would hit: my left leg, which is usually leaning against the door speaker in my Impala, would vibrate 8)
-D

A simple filter would resolve that.

 

[dtube1]

No kidding? Never would have thought of that... :. The tones were, at worst, a very minor annoyance to people listening on systems capable of reproducing them. But, placing a HP on a Classical stream - especially one where pipe organ music was somewhat common - would have yielded phone calls. IME, the classical folks notice every tweak of the processing (I only took one phone call in 8-yrs about the tones, though). Fwiw, I had to mute the gpi's during hours where they weren't expecting tones because the pipe organ music would sometimes trip a decoder (those damned 32' stops).
-D

 

[busyradioguy]

No kidding? Never would have thought of that... :. The tones were, at worst, a very minor annoyance to people listening on systems capable of reproducing them. But, placing a HP on a Classical stream - especially one where pipe organ music was somewhat common - would have yielded phone calls. IME, the classical folks notice every tweak of the processing (I only took one phone call in 8-yrs about the tones, though). Fwiw, I had to mute the gpi's during hours where they weren't expecting tones because the pipe organ music would sometimes trip a decoder (those damned 32' stops).
-D

No I mean a 25 Hz tone filter. Those things were common in the days of automated music reels. You put it in the mastering stage to remove unwanted harmonics right at 25 Hz, so that it won't trigger false stops by the playback system. You also put one in the playback system to keep the 25 Hz tone from being broadcast. Since it only filters 25 Hz, it won't affect the sound quality.

 

[RealityCheckr]

Try re-reading what the man said!

It will "affect the sound quality" when your content includes 25 Hz material and your listeners are using $1000+ speakers

Yes, the classical format is all but dead, but we can still learn something, at the very least....

<snip>. But, placing a HP on a Classical stream - especially one where pipe organ music was somewhat common - would have yielded phone calls. IME, the classical folks notice every tweak of the processing (I only took one phone call in 8-yrs about the tones, though). <snip>

No I mean a 25 Hz tone filter. Those things were common in the days of automated music reels. You put it in the mastering stage to remove unwanted harmonics right at 25 Hz, so that it won't trigger false stops by the playback system. You also put one in the playback system to keep the 25 Hz tone from being broadcast. Since it only filters 25 Hz, it won't affect the sound quality.

 

[dtube1]

Sorry - my bad. I was thinking of the old "turntable rumble" filters. I had an idea in my head at one time to build a fairly steep notch-filter or HP, or even insert an audio DSP (installed-sound system proc like a Symetrix 322 or Rane RPM22) - but that was one of myriad of thing that I never got around too there. Then this past Spring, WFMT quit sending tones, just in time for the HD project (which will hopefully start in August). At that point, the 2020 will probably become the "air monitor" processor and either a Omnia-6 or AP2000 takes over in the air chain.
-D

edit: Gunterm, that is one of the primary reasons I didn't prioritize muting the tones. Classical fans are a tough lot - and they are more likely to have big buck$ in their systems. That said, I have been able to run that station with a fair amount of processing and low-bass without getting anyone too fired up. Classical music should be dynamic - but I hate having to constantly adjust the level on my car radio ;D

 

[gunterm]

I ran a test last night using the 128k mono feed stream and it works So tonight we'll put it into practice and see how it goes. I think I have my orban set to highpass filter above 50hz so they shouldn't hear it over the air.

 

[busyradioguy]

Try re-reading what the man said!

It will "affect the sound quality" when your content includes 25 Hz material and your listeners are using $1000+ speakers

Yes, the classical format is all but dead, but we can still learn something, at the very least....

<snip>. But, placing a HP on a Classical stream - especially one where pipe organ music was somewhat common - would have yielded phone calls. IME, the classical folks notice every tweak of the processing (I only took one phone call in 8-yrs about the tones, though). <snip>

No I mean a 25 Hz tone filter. Those things were common in the days of automated music reels. You put it in the mastering stage to remove unwanted harmonics right at 25 Hz, so that it won't trigger false stops by the playback system. You also put one in the playback system to keep the 25 Hz tone from being broadcast. Since it only filters 25 Hz, it won't affect the sound quality.

You need to re-read what I said. The filter I mentioned will only remove 25 Hz. Everything else will remain. That frequency was chosen for the pure fact that it is inaudible. But if you're in a car with one leg near the speaker, you'll end up with the same result as dtube1 mentioned. The filter will remove that effect. Realistically you owe it to your listeners to do this, even if you only get one or two complaints.

 

[RealityCheckr]

Busy

25 Hz is indeed part of classical organ music, but maybe you are too busy to know it. The following from Wikipedia:

Wolfgang Amadeus Mozart called the organ the "King of instruments"[2]. Indeed, the pipe organ has the most extense frequency response and widest dynamic range of all musical instruments conceived by man.[citation needed] Some of the biggest instruments have 64-feet pipes (a foot here means "sonic-foot", a measure quite close to the English measurement unit), and it sounds to an 8 Hz frequency fundamental tone. Perhaps the most distinctive feature is the ability to range from the slightest sound to the most powerful, "pleine-jeu" impressive sonic discharge, which can be sustained in time indefinitely by the organist. For instance, the Wanamaker organ, located in Philadelphia, USA, has sonic resources comparable with three simultaneous symphonic orchestras. Another interesting feature lies in its intrinsic "polyphony" approach: each set of pipes can be played simultaneously with others, and the sound gets truly mixed and interspersed only when they reached the environment, not in the instrument itself (this is the main difference with digital organs, where the sound comes from loudspeakers which plays the resultant electric waveform of several tones being played).

You need to re-read what I said. The filter I mentioned will only remove 25 Hz. Everything else will remain. That frequency was chosen for the pure fact that it is inaudible. But if you're in a car with one leg near the speaker, you'll end up with the same result as dtube1 mentioned. The filter will remove that effect. Realistically you owe it to your listeners to do this, even if you only get one or two complaints.

 

[busyradioguy]

Busy

25 Hz is indeed part of classical organ music, but maybe you are too busy to know it. The following from Wikipedia:

It doesn't matter if an organ can produce 25 Hz. What matters is can the average person hear 25 Hz? Also, if a classical program inserts 25 Hz tones as described by dtube1, then the program content itself would have to be 25 Hz filtered before the 25 Hz automation tone was injected. Otherwise, any presence of 25 Hz in the program content of the music could trigger false responses by the automation system.

I think you're confusing the listening aspects between broadcast radio vs non broadcast radio. Anyone who spends thousands of dollars on speakers for reproducing music will likely notice other artifacts caused by the broadcasting transmission system of a classical music station. Obviously they will notice anything at and above 15 kHz is missing.

 

[littlejohn]

You can 'hear' lower frequencies, albeit not so much woth the ear as feel them. The Wurlitzer organ in the castle on the Hudson in NewYark (I imiagine it's still there) has 19Hz as the fundamental of the lowest pedal. You can hear it when the organist steps on it.
More to the point, I took a Broadcast Tools encoder and decoder to see how they'd do. They will pass and decode 25Hz, 35Hz, and both inseted in the program and run through every CODEC on a Zephyr Xstreme. They also passed through four web site streams on a broadband connection. Didn't have a dialup, I don't know iof they would run through it or not... but I suspect they would. The system is surprisingly robust, and quite simple. If you can live with three closures and don't have out of band signalling capability, I'd recommend them.

 

[Tom Wells]

Sorry - my bad. I was thinking of the old "turntable rumble" filters. I had an idea in my head at one time to build a fairly steep notch-filter or HP, or even insert an audio DSP (installed-sound system proc like a Symetrix 322 or Rane RPM22) - but that was one of myriad of thing that I never got around too there. Then this past Spring, WFMT quit sending tones, just in time for the HD project (which will hopefully start in August). At that point, the 2020 will probably become the "air monitor" processor and either a Omnia-6 or AP2000 takes over in the air chain.
-D

edit: Gunterm, that is one of the primary reasons I didn't prioritize muting the tones. Classical fans are a tough lot - and they are more likely to have big buck$ in their systems. That said, I have been able to run that station with a fair amount of processing and low-bass without getting anyone too fired up. Classical music should be dynamic - but I hate having to constantly adjust the level on my car radio ;D

I live about 5-6 blocks away from WFMT/WTTW, and was lucky enough to get on a limited-size group tour for audiophiles about 2-3 years ago.

Any strings you can pull to get me in again to to see part of the HD install, I would really appreciate.

I travel about 20-40 %, rest of the time I'm in the area. Please send a PM if this is feasible.

 

[dtube1]

Other than a few phone conversations with their CE, Gordon Carter (great guy), I have no connection to them beyond being an affiliate of their Beethoven Satellite Network and Jazz Sattellite Network (JSN is excellent - highly recommended for overnight NCE's). The fidelity of their syndicated programming is excellent - the quality of the people handling the syndication (with the exception of Carter) is a different story IME.
-D

 

[Tom Wells]

They had 5 syndication upstreams feeding at once and someone had to monitor all 5 at once to make sure they are feeding
OK. It was hard to listen to, even just walking by. I didn't think I could reliably keep an ear tuned on 5 at once.
That may be part of the problem there.