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New Sampling Techniques Make Up For Lost Data

Posted by timothy on from the putting-stuff-back dept.

An unnamed reader writes: "Professors at Vanderbilt and the University of Connneticut have published a non-uniform sampling theory that could yield better quality digital signals than the standard Uniform sampling techniques pioneered by Shannon at Bell Labs. The Vanderbilt press release and link to the published paper can be found here."

5 of 162 comments (clear)

  1. Re:So.... by pmc · · Score: 5, Informative

    No.

    As the abstract says

    "The new theory, however, handles situations where the sampling is non-uniform and the signal is not band-limited."

    So it isn't applicable to digital music (as this is band-limited by our hearing, and we can pick the sampling interval) but other signals that cannot be sampled well by regular sampling (either in time or in space). Examples given are seismic surveys and MRI scans. But you knew this as you'd have taken the time to read the linked article first, wouldn't you?

  2. Nyquist, not Shannon by s20451 · · Score: 5, Informative

    It was at Bell Labs ... but the guy who developed the Uniform Sampling Theorem was Nyquist, not Shannon.

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  3. Some folks seem to be missing the point on the MRI by fatboy-fitz · · Score: 5, Informative

    example. It was not provided to show a compression mechanism in which the original image could be compressed. It was intended to show that if you sample randomly, then their algorithm can come up with a highly accurate representation of the original. The implication here is that given current capability to sample, if you apply the new technique, you can get a better image/audio recording using their technique, than you can using the current fixed sampling interval technique, making the image more vivid, or the musical recording more lifelike than current sampling provides.

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  4. Time vs. Frequency by PingXao · · Score: 5, Informative
    Classical techniques also require that the original signal be "band limited" - a technical term meaning that the signal must stay within certain, defined limits.

    This is not quite accurate. The original signal is not "required" to be band-limited. Rather, it is accepted that frequencies outside of your design bandwidth will not be captured. The signal can stray outside of the "defined limits", but should it do so that information will be lost. Furthermore, Fourier's math tells us that a signal that is limited in time is unlimited in frequency, and a signal that is limited in frequency is unlimited in time. This has important ramifications. The biggest - and most obvious - is that all man-made signals are limited in time and therefore unlimited in frequency. Ergo there will ALWAYS be information lost no matter what bandwidth you design for.

    Now to read the rest of the article - it sounds intriguing...
  5. Both are right: by volpe · · Score: 5, Informative
    From Engineering Fundamentals


    The sampling theorem is considered to have been articulated by Nyquist in 1928 and mathematically proven by Shannon in 1949. Some books use the term "Nyquist Sampling Theorem", and others use "Shannon Sampling Theorem". They are in fact the same sampling theorem.