tional codes in worst case partial-band noise, the performance improves with K, just as it did in Figures 2.76,2.78, and 2.80 in the absence of diversity. However, unlike Figure 2.77 for orthog- onal convolutionally coded systems in worst case n = 1 band multitone jam- ming, the addition of optimum diversity causes the performance in Figure 2.97 to degrade with increasing K. By comparison, for the dual-K convolu- tional codes in worst case n = 1 band multitone jamming, with or without diversity. Figures 2.79, 2.81, and 2.98 show that the best performance of coded FH/MFSK systems with optimum diversity tends to improve with K in worst case partial-band noise, and degrade with K 2 for low bit error rates in worst case tone jamming, the impact of the type of jamming on the AJ capability becomes more significant for larger K. For example, at P = 10-5 , Figure 2.98 shows that worst case tone jamming is about .6 dB more effective against dual-K, rate 1/2 convolutional codes with optimum diver- sity than worst case noise jamming at K = 2; this difference rises to 6.14 dB at K = 5. The performance improvements in various coded FH/MFSK systems pro- vided by the addition of optimum diversity is illustrated in Figures 2.99-2.102. Coding Countermeasures M-ARY ORTHOGONAL CONVOLUTIONAL CODE WITH OPTIMUM DIVERSITY WC n= I BAND MULTITONE WC PARTIAL - BAND NOISE Figure 2.97. Variation in performance of FH/MFSK systems with orthogonal con- volutional coding and optimum diversity versus K = logM and type of jammer. By comparison with no diversity in multitone jamming (Figure 2.77), performance degrades with increasing K. WC n = I BAND MULTITONE WC PARTIAL- BAND NOISE DUAL-K, RATE 1/2 CONVOLUT- IONAL CODES WITH OPTIMUM DIVERSITY Figure 2.98. Same as Figure 2.97, but for dual-K, rate 1/2 coding. As in no diversity case with multitone jamming (Figure 2.79), best performance at low P6's occurs when K = 2. Recall that all of these results are for soft decision energy detection, linear combining, and perfect side information. Non-Coheren