n the wideband energy detector by 6.1 dB. Thus, the attempt is in vain. there is just no way the minimum channel requirement can be ignored. This being the case, the communicator need never fear that the PB-FBC will ever be used by the interceptor as long as the required number of minimum channels is forced (by design) at low hop rates to be above some threshold (say, greater than 100) for which the cost per dB of advantage is u intenable. Turning now to the FH/PN performance entry in Table 1.5 for the mini- mum channel PB-FBC at Rh corresponding to NT = 107, the 2.1 dB advan- tage over the wideband radiometer requires only 13 channels. This therefore represents a situation where the interceptor might indeed justify the PB- FBC. A good strategy for the communicator should be to avoid designing an FH/PN system with the subject parameters. If such a low hop rate is deemed necessary, the communicator should avoid PN spreading, at least at such a high chip rate. Table 1.7 shows the level of PB-FBC performance which may be expected if a lower chip rate is employed with the above hop rate. Again it can be seen that the tradeoff is a better intercept SIN require- ment, but at the expense of a significantly increased number of minimum channels. Thus, although the interceptor might opt to build a 13-channel detector when the PN chip rate is 1000 times the hop rate, he will likely refrain from a 125-channel unit when the chip rate is 100 times the hop rate, in favor of some more economical approach. Having now reviewed a rather wide range of FH and FH/PN parameters, it appears reasonable to conclude that: 1. For any of the pure FH cases, the interceptor will be forced to the wide- band energy detector. 2. PN spreading to the FH pulses is not essential to the prevention of chan- nelized detector usage, nor does it directly add to the state of LPI. Performance and Strategies Assessment Table 1.7 Performance of a minimum channel PB-FBC for a fixed hop rate and different PN chip rates; NT = 107. Detector No. of Channels DS/N° 