PFA estimates may be directly related to the correct threshold value and the comparator threshold will be continually adjusted to compensate for all external and internal receiver noise temper- ature and gain changes. Contemporary microprocessor-based algorithms make this method highly viable. (2) Channelized Detectors In most situations, because of the small practical processing gain achievable at a significant cost over the wideband detector a channelized detector is unlikely to be used. Apart from these considerations, this subsection will investigate channelized detectors from a purely operational topology. As representative of the considerations involved for channelized detec- tors, the 125 minimum channel PB-FBC of (4) in Section 1.2.1.2 will be used to illustrate the tradeoffs and problems. Stated explicitly, the task is to receive the total SS band of frequencies and downconvert 125 selected hop fre- quency positions into Wh-wide channels, each followed by detectors, FH pulse period integrators, and comparators. The first question that must be answered is: which 125 of the NT = 106 possible channels should be selected? If the communicator's FH pattern is essentially random and uniform over the hop frequency set, then it can be rightfully argued that it makes no difference which frequencies are cho- sen. Whether they are uniformly spaced and contiguous on some 125 W wide sub-band or randomly dispersed across the total SS band should have no effect on the statistical parameter Phit. From an ease of implementation point of view, even without supplying details, it is well conjectured that a receiver built around the contiguous sub-band would be the simplest to realize in terms of downconversion and IF amplification. The uniformly spaced but separated channels would be the second-best choice on the same basis. The communicator also appreciates this and, if he surmises that either approach has been adopted by the interceptor, even if he is not aware of which specific hop channels (uniformly spaced or contiguous