An event qualifier for double differentiator time of arrival estimators

Abstract

A low variance pulse time-of-arrival (TOA) estimator is considered. It should be insensitive to all non TOA parameters and operate without a priori information about any pulse parameters assuming they are constrained to a wide range. The estimator is driven by a wide-band input diode detector with a narrow filtered base-band output. The double differentiator TOA estimator is selected. It marks inflection points of pulses and noise. An event qualifier is necessary to distinguish the pulse-only TOAs and is synthesized using the unique polarities of pulses and their derivative by detecting level crossings on both. It experiences errors of mis-detection and false alarm with noise present. Error performance is established at constant false alarm rate (FAR), set by choice of threshold level pairs. Detection probability is maximized by simulation over the locus of constant FAR levels. Design information for operating a qualifier is provided.