The equations:

Let the Damping Ratio be z and the amplitude of two successive peaks be A1 and A2.

ln (A1 / A2) = Pi * z / sqrt ( 1 - z**2)

z = 1 / sqrt {1 + [Pi / ln(A1 / A2)]**2}

Q = 0.5 / Damping Ratio("STO1" for A1 and "STO2" for A2.)