Output-Energy Filters in Noncoherent Pulse-Event Detection

Digital matched filters are pivotal for detection of pulses in numerous applications. But compromises are necessary in situations of phase uncertainty, degrading the optimality matched filtering offers. The problem is compounded when (say, for avoidance of intersymbol interference) in colored noise the filter size is restricted below optimal length. In such circumstances energy detection can be attractive. Here we explore employment of so-called output-energy filters as candidate pre-filters for traditional square-law nonlinear energy detectors. We show conditions where an output-energy processor outperforms a length-deficient matched filter used in pulse arrival time location and in a quadrature receiver for noncoherent FSK detection. Peak response offsets in some length-deficient matched filter responses are encountered and shown to require care in interpreting even noisefree data records. In certain operating regimes output-energy processing has advantages, offering phase-blind detection ability unavailable with matched filters.