e for the NT quadrature I & D outputs. If, as has been previously done, one assumes that l = 1 for simplicity of analy- sis, then the accumulators which would normally precede these threshold devices can be eliminated with no loss in generality. this has been done in Figure 1.13. When noise-only is present, an output from any of the N T inphase I & Ds which exceeds the channel threshold k will produce an output from the in- phase logical OR and a corresponding output from the in-phase (l = 1) threshold device. This constitutes a false alarm and can occur at any integer multiple of the hop time, Similarly, an output from any of the quadra- ture I & Ds which exceeds the channel threshold k will produce a false alarm which can occur at any odd multiple of half the hop time. Since potential false alarm decisions are now being made every half-hop interval (Th/2), the false alarm rate is again the product of the decision rate (2/Th) and the false alarm probability per decision, PFA. Letting PEAL denote the per-channel, per- hop false alarm probability, i.e., the probability that an individual I & D out- put exceeds the channel threshold k, then, clearly, PFA and PFAI are related by the familiar binomial equation FA=1-(1-Pra))" (1.47) and the corresponding false alarm rate is given by (1.48) which, for PFAI < 1, becomes approximately (1.49) To achieve a false alarm rate equal to that of the wideband detector with overlapping I & Ds, (1.49) is equated with (1.25). Then, (1.50) (1.51) Note that (1.51) is the identical equation which relates PEA and PFAI for the "ideal" filter bank combiner (see (1.8b)). Alternatively, for Figure 1.13 to achieve the same false alarm rate as the "ideal" FBC, the false alarm probability PFA or the per-channel false alarm probability PEAI must be reduced to half its previous value. Interception Detectors To determine the overall probability of detection PD, D, it is again assumed that, with signal-plus-noise present at the input, an output from either (unit level) threshold device constitutes