Does anybody else hear this...? - Page 3

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Thread: Does anybody else hear this...?

  1. #21

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    Quote Originally Posted by kevtronics View Post
    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.
    El Rushbo has been doing that long before PPM's existed, but his ego appreciates the fact that you noticed.

  2. #22

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    Quote Originally Posted by DavidEduardo View Post


    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.
    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.

  3. #23
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    Quote Originally Posted by Anton P View Post
    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.
    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.
    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.
    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.
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