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Method and apparatus for processing a physiological signal

  • US 6,647,280 B2
  • Filed: 01/14/2002
  • Issued: 11/11/2003
  • Est. Priority Date: 09/30/1999
  • Status: Expired due to Term
First Claim
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1. A method of signal processing for filtering noise from an input signal, wherein the input signal is noisy, the method comprising the following steps:

  • (a) calculating a numerical transform of the input signal to determine a fundamental period, wherein the numerical transform is calculated at each of a plurality of incremental periods by multiplying samples of the input signal by first and second periodic orthogonal waveforms of period equal to the selected incremental period;

    (b) indexing through a buffer storing the first periodic waveform and a buffer storing the second periodic waveform, where the index is inversely proportional to a selected period to selectively decimate the length of the period;

    (c) scaling and summing the calculated numerical transforms for a given incremental period to yield the fundamental period in the input signal; and

    (d) utilizing the fundamental period for filtering noise from the input signal.

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