Radar target identification: Estimating the start of the late time resonant response

Determining the correct start for the late-time or resonant response window is a crucial parameter for uncooperative, resonance-based target identification by means of ultra-wideband radar. For low resonance (low-Q) targets this is particularly vital, as the processing must be set late enough to avoid including signal data caused by early-time (non-resonant) scattering, but early enough to maximise the signal-to-noise ratio for the late-time component of the target response. Without knowledge of the target's orientation to the incident excitation, the late-time start must be determined from the signal data alone. The spectral norm of the impulse response data matrix (Hankel matrix), examined over a sliding window, provides a robust indicator of the late-time commencement.