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Frequency measuring and monitoring apparatus, methods and systems

  • US 4,319,329 A
  • Filed: 02/21/1980
  • Issued: 03/09/1982
  • Est. Priority Date: 02/21/1980
  • Status: Expired due to Term
First Claim
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1. Apparatus for measurement, relative to a reference frequency f, of frequency deviation Δ

  • f of frequency of a substantially single-frequency sinusoidal waveform having electrical values including zero-crossings and being provided to said apparatus, said apparatus comprising;

    means for generating triggering signals, each triggering signal being in response to a respective one of at least some of said zero-crossings of said waveform;

    converting means being responsive to said waveform and to said each said triggering signal so that said converting means produces n digital representations, n being a whole number of at least 4, corresponding to n electrical values of said waveform occurring during a period 1/f of the reference frequency, one of said n digital representations corresponding to a time-wise first one of said n electrical values, said first one value being located fΔ

    t reference cycles relative to the zero-crossing nearest said each said triggering signal, Δ

    t being a time interval; and

    stored program computing means for receiving said n digital representations and computing a leakage coefficient of the discrete Fourier transform of said n digital representations and then computing the measured frequency deviation Δ

    f from at least the leakage coefficient so that the frequency deviation so computed is substantially accurate in view of the number n and the quantity fΔ

    t.

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