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Calibration of frequency monitors having dual etalon signals in quadrature

  • US 7,813,886 B2
  • Filed: 12/04/2007
  • Issued: 10/12/2010
  • Est. Priority Date: 12/07/2006
  • Status: Active Grant
First Claim
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1. A method of calibrating a frequency monitor having dual etalon signals in quadrature, the method comprising:

  • a) providing calibration data in the form of triples (xi, yi, ν

    i) indexed by i, wherein for each triple, xi is a first etalon signal at a known frequency ν

    i and yi is a second etalon signal at said known frequency ν

    i, and wherein said first and second etalon signals are substantially in quadrature;

    b) fitting an ellipse to the set of points (xi, yi), wherein said ellipse is parametrically defined according to
    x=x0+A cos θ


    y=y0+B sin(θ



    );

    c) calculating an angle parameter θ

    i of said ellipse for each of said points (xi, yi);

    d) fitting a line to the set of points (θ

    i, ν

    i) to provide a linear angle-frequency fit, wherein said line is parametrically defined according to ν

    =sθ



    0;

    e) providing said parameters s and ν

    0 and said parameters A, B, x0, y0, and ε

    as ν



    ) calibration outputs;

    f) calibrating said frequency monitor having dual etalon signals in quadrature using said ν



    ) calibration outputs.

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