 of these systems is illustrated in Table 2.20 for an over- all bit error rate of 10-5 and worst case noise and tone jamming. The best of these systems requires Eb/N1 = 9.39 dB to achieve the desired Pb in any non- adaptive jamming environment. Recall that the best concatenated FH/MFSK system with an RS outer code, a dual-K inner code, and no diversity required EIN, = 9.38 dB under the same design constraints (Table 2.14); however, this was with a rate 1/3 inner code, whereas Table 2.20 is restricted to rate 1/2 inner codes. (If we extended Table 2.20 to include rate 1/3 inner codes, Table 2.20 Required SNR and optimum diversity Mopt to achieve Pb = 10-5 for FH/MFSK systems with outer codes, dual-K, rate 1/2 inner codes, and optimum diversity for worst case partial-band noise and n = 1 band multitone jamming. Note that Mopt ~ 2 in almost all cases, implying concatenated RS/dual-K coding is quite powerful even without diversity. Noise Multitone RS Code n, k Inner Code Pb N1 Eb dB 255, 191 8.38 X 10-3 11.52 10.25 511, 447 3.76 X 10-3 11.32 10.02 1023, 959 1.73 X 10-3 11.44 10.13 15, 7 9.47 X 10-3 11.11 11.77 63, 31 2.18 X 10-2 10.49 11.14 255, 191 1.11 X 10-2 1023, 959 2.31 X 10-3 5.43 X 10-3 10.48 12.98 63,31 2.78 X 10-2 11.76 511, 447 6.40 X 10-3 15, 7 1.50 X 10-2 13.40 255, 191 1.77 X 10-2 11.29 31, 15 3.03 X 10-2 14.62 1023, 959 4.46 X 10-3 Coding Countermeasures the performance with optimum diversity would not improve much as argued earlier.) The 9.39 dB SNR benchmark in Table 2.20 should more fairly be compared with the best rate 1/2 inner code in Table 2.14, which requires Eb/N1 = 10.19 dB, to measure the improvement due to diversity. And the amount of diversity in Table 2.20 is small (of the order of 2). Still, to place this result in perspective, the best RS/dual-K/optimum diversity system is only slightly improved over the Eb/N, = 9.43 dB requirement of Table 2.16 for the best binary convolutional code with optimum diversity. So, as a final exercise, we will now determine how much additional improvement i