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Does anybody else hear this...?

kevtronics said:
Is that why Rush Limbaugh likes to shuffle his papers around so much? Normally that would be bad on-air manners to have it audible on the microphone, but he likes to pause a lot for dramatic effect and the paper rustling helps fill up the dead air with audio for the PPM encoders to work with.
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El Rushbo has been doing that long before PPM's existed, but his ego appreciates the fact that you noticed.
 
DavidEduardo said:


You are not hearing the PPM encoding; you are hearing the Voltair, when set to high, pumping up noise on the frequencies used to encode to make the Nielsen encoder emit a PPM tag. When you selectively enhance specific narrow frequency bands, and there was no audio of value there to begin with, what gets amplified is junk. The junk masks the PPM tag just fine, but is essentially amplified noise.
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Then why do I hear distinctive 3 times per second data burst changes typical of PPM encoding scheme during program audio passages that contain loud and dense or busy midrange material (think wave crash or jet airplane fly by sounds)? My guess is that Voltair is isolating and boosting PPM encoding tones in order to out scream interfering frequencies, to provide more SNR for PPM receivers to work with. How else can you encode distinct tones into broadband noise? There has to be more to it than just simply boosting masking frequencies in program material in order to fool the PPM encoder into encoding. Another clue is that take two radio stations with both Voltairs set on the same "high" settings, one is Hispanic Pop and another is Classic Rock. The rock station has much more noticeable PPM/Voltair noise while Hispanic station is hardly noticeable. It appears that electric guitar grunge forces much louder encoding levels.
 
Anton P said:
Then why do I hear distinctive 3 times per second data burst changes typical of PPM encoding scheme during program audio passages that contain loud and dense or busy midrange material (think wave crash or jet airplane fly by sounds)? My guess is that Voltair is isolating and boosting PPM encoding tones in order to out scream interfering frequencies, to provide more SNR for PPM receivers to work with.
Click to expand...

The space allocated for PPM tags is approximately 4.5 seconds long. There are, at most, 12 to 13 of them per minute, not 3 per second.

The Voltair does not tamper with the PPM encoding; it tries to raise the consistent levels of the station audio to the point where it is high enough to allow PPM gags to be transmitted. What that does, sometimes, is to amplify noise, not program content.

How else can you encode distinct tones into broadband noise? There has to be more to it than just simply boosting masking frequencies in program material in order to fool the PPM encoder into encoding.
Click to expand...

It's about the density of the audio on at least one of the frequencies the Nielsen encoder can pick to encode on. Think of the Voltair as a very selective AGC which only increases the level on the encoder frequencies.

Another clue is that take two radio stations with both Voltairs set on the same "high" settings, one is Hispanic Pop and another is Classic Rock. The rock station has much more noticeable PPM/Voltair noise while Hispanic station is hardly noticeable. It appears that electric guitar grunge forces much louder encoding levels.
Click to expand...

There are many more variables. For starters, classic rock was recorded in pre-digital days and the dynamic range is broader than present day rhythmic and pop songs that look like square waves. So contemporary Spanish language rhythmic material is far denser, and easier to encode in.
 
DavidEduardo, I went through my old posts and found this discussion. I found out why rock station (WBGG) had louder PPM tones and why hispanic station (WZTU) was not as noticeable. At that time WBGG had new black cased Nielsen encoder that had enhanced CBET software with louder tones while ZTU had old Arbitron gray box with tones not as loud. But both had Voltairs set on same enhancement level. Enhanced CBET fed into Voltair that was setup for old Arbitron box = extra loud tones. I witnessed encoder box swap from old to new on Y100 and immediately heard louder tones after the switch. That kinda solved the mystery.
 
Anton P said:
DavidEduardo, I went through my old posts and found this discussion. I found out why rock station (WBGG) had louder PPM tones and why hispanic station (WZTU) was not as noticeable. At that time WBGG had new black cased Nielsen encoder that had enhanced CBET software with louder tones while ZTU had old Arbitron gray box with tones not as loud. But both had Voltairs set on same enhancement level. Enhanced CBET fed into Voltair that was setup for old Arbitron box = extra loud tones. I witnessed encoder box swap from old to new on Y100 and immediately heard louder tones after the switch. That kinda solved the mystery.
Click to expand...

Interesting observation. I believe that to get the maximum minutes that too many stations have the Voltair at "11" and it makes listening tedious. They may get credit for every minute, but they lose the listeners due to fatigue in rapid time.
 
Yes, it's a shame how loud the encoding has to be. But I found that many people cannot recognize the noise without some help. So I made a recording of audio before the encoder and after, then I phase inverted the input recording and summed it with output. That extracted the tones. I then was able to increase tone loudness in order to better highlight before/after difference. That made a striking demo.
 
Anton P said:
Yes, it's a shame how loud the encoding has to be. But I found that many people cannot recognize the noise without some help. So I made a recording of audio before the encoder and after, then I phase inverted the input recording and summed it with output. That extracted the tones. I then was able to increase tone loudness in order to better highlight before/after difference. That made a striking demo.
Click to expand...

Actually encoding doesn't have to be that loud. As David mentioned, some stations have their Voltaire box set to 11. I suppose stations that have really densely-processed audio would benefit from running Voltair hot, because their TSL isn't expected to stick around more than 30 minute blocks of time anyway. If I had a classical station, there would be no way I'd run Voltaire.
 
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