Draft revision of IEEE STD 1139-1988 standard definitions of physical quantities for fundamental, frequency and time metrology-random instabilities

This is a draft revision of IEEE Std 1139-1988 Standard Definitions of Physical Quantities for Fundamental Frequency and Time Metrology. This draft standard covers the fundamental metrology for describing random instabilities of importance to frequency and time metrology. Quantities covered include frequency, amplitude, and phase instabilities; spectral densities of frequency, amplitude, and phase fluctuations; variances of frequency and phase fluctuations; time prediction; and confidence limits when estimating the variance from a finite data set. The standard unit of measure for characterizing phase and frequency instabilities in the frequency domain is L(f), defined as one half of the double-sideband spectral density of phase fluctuations. In the time domain, the standard unit of measure of frequency and phase instabilities is the fully overlapped Allan deviation σ_y(τ) or the fully overlapped modified Allan deviation Mod _σ(τ)