31st Annual Precise Time and Time Interval (PTTI) Meeting GENERALIZATION OF THE TOTAL VARIANCE APPROACH TO THE MODIFIED ALLAN VARIANCE*

The Total variance approach involves periodically extending a data sequence beyond its normal meusurement duration and in such a way that a particular time statistic is expected to have the same value with extended data as without. For those statistics which estimate components of broadband noise processes, the approach can signi;ficantZy reduce the spread or uncertainty in the result. We describe a Total variance approach for improving the confidence of the estimation of the modified Allan variance (Mvar) for the five common integer power-low noises and which simultaneously has low, easily removable bias. We have found in simulation studies that if a relection-only extension procedure is applied to Mvar’s individual estimates, we obtain a new estimate of Mvar which exhibits an increase in equivalent degrees of freedom at mid- and long-term integration times.