Fundamental limitations to broadband time delay resolution for two sensors

The authors seek to quantify the fundamental limitations to resolving two delays. They emphasize that just as in the single parameter estimation problem, resolution problems are subject to a threshold effect, This means that the resolution ability of any processing scheme will suddenly deteriorate below a certain SNR. The authors present a conservative bound on the probability of resolution that exhibits this property, and they illustrate and quantify the resolution threshold behavior by simulation. They show that (roughly) a value of the quantity [(D₁-D₂)/(square root of Cramer-Rao lower bound)] greater than 7.5 is required to obtain reliable estimates of D₁ or D₂