9 1023, 959 1.73 X 10-3 13.83 12.66 15, 7 1.42 X 10-2 13.00 13.94 63, 31 3.27 X 10-2 11.92 12.97 255, 191 1.67 X 10-2 10.80 11.75 1023, 959 3.46 X 10-3 11.12 11.93 9.51 X 10-3 12.64 15.35 63,31 4.87 X 10-2 10.64 13.52 511, 447 1.12 X 10-2 12.14 15, 7 2.81 X 10-2 10.78 15,45 255, 191 3.31 X 10-2 13.28 31, 15 5.88 X 10-2 16.33 1023, 959 8.64 X 10-3 14.62 Coding Countermeasures non-adaptive jamming, whereas we need Eb/N, = 11.75 dB in Table 2.19, and the diversity required for the RS systems is also larger by more than a factor of 2. As in the section on coding without diversity, we again conclude that RS codes need to be concatenated with other good codes to achieve satisfac- tory performance. In particular, we want to look at systems that combine RS outer codes with convolutional inner codes over FH/MFSK channels with optimum diversity. First assume that the inner code is a dual-K, rate 1/2 convolutional code. Each RS code symbol over GF(2°) is composed of L inner code symbols over GF(2*). The M-ary channel symbols are transmitted as Mopt diversity chips which are energy detected in the receiver. These chip energies are lin- early combined using the soft decision metric with perfect side information. The convolutional decoder uses these observables to make hard M-ary deci- sions. These M-ary symbols are unscrambled (assuming interleaving between the inner and outer codes) and reformatted into Q-bit RS characters, which are then fed to the RS decoder. As before, a given outer code Pb maps into an RS symbol error rate PQ [21], which translates into an M-ary symbol error rate , corresponding to an inner code Pb: combining (2.153) and (2.154), we have inner (2.171) Finally, this inner code Pb is converted into a required SNR for a dual-K, rate 1/2 convolutional code with optimum diversity using (2.151), (2.159), and (2.162)-(2.164), with overall code rate (2.172) exclusive of diversity. That is, noise inner code (2.173) multitone (2.174) where G() and Y are defined in (2.151) and (2.164), respectively. The performance