Principles of Modern Radar - Volume 2 1891121537

16.5 Exploiting Knowledge for Detection and Classification 727SNR Loss (dB)0 40−10−202535CLRVNT30FFT20−3015Phase Mismatch Only10−40Amplitude Mismatch Only5Total Mismatch−500 0.5 1 1.5 200 0.5 1 1.5 2Dwell Time (seconds)Dwell Time (seconds)(a)(b)FIGURE 16-11 (a) SNR loss variation over dwell time. (From Gürbüz [84]. With permission.)(b) Output SNR variation over dwell time normalized by input SNR for the ideal, clairvoyantdetector and FFT-based linear-phase detector. (From Gürbüz et al. [100]. With permission.)Normalized SNR (dB)match the target of interest, in this case, human targets. This has led some researchersto propose incorporating a priori information about human kinematics into the detectordesign, as discussed in more detail in the next section.16.5 EXPLOITING KNOWLEDGE FOR DETECTIONAND CLASSIFICATIONIn practice, it is impossible to realize the ideal, clairvoyant detector because the exact targetreturn is unknown. However, if the goal is to design detectors and classifiers specificallyfor human targets, then there is a priori knowledge about the target that can be exploitedto design better algorithms—that is, it is known that the target is human. As mentionedduring the discussion on human spectrograms, the kinematics of human gait are uniqueand represents a priori knowledge about the desired target that can be exploited for humandetection and classification.One example of incorporating kinematic information into detector design is to usethe Boulic-Thalmann model to derive a parametric approximation to the expected targetresponse [100]. Consider the antenna–target geometry illustrated in Figure 16-12, whereit is assumed that human motion is linear along a constant angle, θ, relative to the initialtarget vector, r 1 . The vector h between the initial and final target locations representsInitial TargetLocationr 1qhr NFinal TargetLocationFIGURE 16-12Antenna–targetgeometry assuminghuman motion alonga linear path. (FromGürbüz et al. [100].With permission.)AntennaLocation