tial-band noise. Imagine then an electronic warfare (EW) scenario in which both adversaries begin with innocuous equipment and then feel compelled to alternately escalate the EW ante. Initially, there is an uncoded FH/MFSK system opposed by a broadband noise jammer. Then the ECM opponent introduces a worst case partial-band noise jammer, with the dramatic result that the communication link performance degrades severely to the inverse linear relationship of (2.21). To combat this increased threat, the communication system counters with a series of increasingly more sophisticated coding techniques, beginning with sim- ple diversity. Each improved coding scheme brings the AJ performance closer to the initial AWGN situation, and with the concatenated dual- K/optimum diversity system, a balance is achieved between the ECM and ECCM upgrade effectiveness. Of course, the jammer can still resort to the increased capability of worst case multitone jamming if K > 2, but the communicator has an arsenal of even more powerful codes (such as the RS/convolutional code/optimum diversity scheme analyzed below) to neutralize this ploy. We can also use the asymptotic results to explain some of the multitone jamming behavior that we have previously observed graphically and in Table 2.16. From (2.164) and Table 2.17, we see that the exponential per- formance coefficient kR'ly in (2.167) is proportional to (Be)- for uncoded, M-ary orthogonal, and dual-K convolutionally coded signals with optimum diversity in worst case multitone jamming; the same coefficient is propor- tional to K/4 in worst case partial-band noise. These quantities are shown in Table 2.18. Since a larger coefficient kR'ly contributes to a smaller Pb, we can understand why the noise jamming performance of these systems improves monotonically with K, while the tone jamming performance is best at K = 2, as seen earlier in Figures 2.97 and 2.98 and Table 2.16. In the uncoded and dual-K cases, we also see why worst case noise jamming is more effective than worst case tone 