Two-step Sequential Detection in Agile-beam Radars: Performance and Trade-offs

In this work, we consider a surveillance radar equipped with an electronically scanned antenna and study the performance of a two-step sequential detection procedure, where, for each resolution cell, a second observation is taken if a reliable decision cannot be made after the first one. At the design stage, we optimize the available degrees of freedom (namely, dwell time and detection thresholds) so as to maximize the detection rate (DR), defined as the average number of detections from a target per unit of time, under a constraint on the false alarm rate (FAR), which is the average number of false alarms per unit of time from the inspected area. This is motived by the fact that DR and FAR, beside of being per se meaningful figures of merit for parameter tuning, allow a fair performance comparison among detection strategies with different scanning policies. Examples are presented to illustrate the effects of this design philosophy under the two relevant situations of a slowly-fluctuating and a fast-fluctuating target response, also in the presence of clutter.