The third-difference approach to modified Allan variance

摘要

This study gives strategies for estimating the modified Allan variance (MVAR), and formulas for computing the equivalent degrees of freedom (EDF) of the estimators. A third-difference formulation of MVAR leads to a tractable formula for EDF in the presence of power-law phase noise. The effect of estimation stride on EDF is shown. First-degree rational-function approximations for EDF are derived, and their errors tabulated. A theorem allowing conservative estimates of EDF in the presence of compound noise processes is given.