Estimation and discrimination for Swerling targets

The radar cross section (RCS) of most targets is sensitive to the aspect angle of the target with respect to the radar and fluctuates from pulse-to-pulse or scan-to-scan. The RCS fluctuations are typically characterized as one of four Swerling types. Examining the receiver operating characteristic (ROCs) curves for detection of Swerling targets shows that Swerling targets of type 3 and 4 can be detected with similar probabilities at lower transmitted energy than that required by Swerling targets of type 1 or 2. Thus, effective discrimination between Swerling types can be used to improved the utilization of radar resources by coordinating the waveform type and duration with the target type. Since waveforms with frequency diversity that induces pulse-to-pulse fluctuations are of interest, parameter estimation and discrimination for Swerling targets of types 2 and 4 are considered in the paper. Maximum Likelihood (ML) estimation of the amplitude parameters (i.e., SNR) is developed for both Swerling types, and techniques for discriminating between Swerling 2 and Swerling 4 targets are discussed.