PCM, Upsampling, can someone please explain?

Discussion in 'Archived Threads 2001-2004' started by gomez_a, Mar 16, 2002.

  1. gomez_a

    gomez_a Stunt Coordinator

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    Hello,

    Can somone please explain to me what PCM is . . . I mean, I know that it stands for Pulse Code Modulation, but I don't know how PCM figures in my HT system. Is PCM the input source signal used for playing CD's (I use a Toshiba SD2300 DVD player to play CD's). Any links explaining this would be helpful as well

    Also, I have an ONKYO 898 (which has 192kHz/24bit DACs) w/upsampling capability. Upsampling, as I understand it, doubles the CD's original sampling freq during playback for a more 'detailed' sound reproduction (so the manual says) - what are your impressions of upsampling of std CD recordings (which i think are at 44kHz?)

    Also, how can upsampling improve on the sound that has already been recorded at a lower sampling freq? Does the DAC algorythms use some type of interpolation to "guess" as to what the recording's signal would be between point in the the new sampling freq?

    Thanks!
     
  2. Dennis B

    Dennis B Stunt Coordinator

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  3. Larry B

    Larry B Screenwriter

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  4. Larry B

    Larry B Screenwriter

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    And here's some more info:

    "The following is a brief interview between Dave Clark and Tony Taddeo based on the Digital Antidote Two

    review. For more information on the Digital Antidote and to read more about Tony Taddeo's thoughts on the

    changing world of digital technology, visit the Taddeo website.

    An Interview with Tony Taddeo

    Q. Is the Digital Antidote Two compatible with the new formats?

    A. Yes. The Digital Antidote Two will upgrade either narrow band SACD or 24/96 to be comparable to wide

    band SACD or 24/192.

    Q. What is upsampling and is it compatible with the Digital Antidote Two?

    A. Yes, the Digital Antidote Two is completely compatible with upsampling. Upsampling is a new term for an old

    technology. It is a variation of (subset of) oversampling.

    In oversampling the filter frequency is raised to a much higher frequency that is a multiple of 44.1 kilohertz. The

    information remains bandwidth limited to 44.1 kilohertz, thus causing phase distortion.

    In upsampling the filter frequency is raised to a higher frequency that is not a multiple of 44.1 kilohertz, but an

    arbitrary frequency that may be divided by 44.1, 48, or 96 kilohertz. This gives the upsampler the ability to mate

    dissimilar frequencies. Thus a 24/96 DAC may be used with a normal 16/44.1 CD. This cuts the cost of having

    to have two separate DAC’s. Because of this cost cutting most 24/96 DAC’s will be upsampling. Like an

    oversampler, the information is bandwidth limited to 44.1 kilohertz, and is phase distorted.

    This is a point of great confusion to consumers, because they wrongly believe an upsampler somehow converts

    the information to 24/96. This absolutely is not true! An upsampler is just another form of oversampler. Some

    have suggested that an upsampler results in slightly lower jitter, but even if it does, this is not the best way to

    reduce jitter. Because 44.1 kilohertz is not an integer of 96 kilohertz, you do have to lose some information by

    upsampling. This is why the industry went to oversampling rather than upsampling over a decade ago. You

    could legitimately call your present oversampling CD player a synchronous upsampler."

    Larry
     
  5. gomez_a

    gomez_a Stunt Coordinator

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    THANKYOU FOR THE INFO!
     
  6. Bob Br

    Bob Br Agent

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    gomez_a,
    Thanks for asking the question. I, too, have recently purchased na Onkyo 898 and was struggling with the same issue just this past weekend. It's great to have a place like this to get answers to your questions. You guys are great[​IMG]
    Bob
     
  7. gomez_a

    gomez_a Stunt Coordinator

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    Bob,

    How do you like the 898. I'm very pleased w/mine, but there's so many features/adjustments that it takes awhile to learn all the capabilities of the unit.

    Have you messed around with teaching the Onkyo remote commands from otehr remotes? I follwed the instructions, but it didn't work for me - did you have any luck?
     
  8. gomez_a

    gomez_a Stunt Coordinator

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    is anyone familiar w/this book:
    Principles of Digital Audio
    by Ken C. Pohlmann
    I saw the info on it in Amazon, but I'm not up for reading a college engineering type textbook w/all the math woorlked out, blah, blah, those days are behind me [​IMG]
     

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