e of 1/4 as in (1.56). Furthermore, those limits are achieved for values of p (see (1.78) and (1.84)) which are different but relatively close. Figures 1.13-1.15 characterize the performance of FH/QASK-16 in the presence of noise jamming, as computed from the results given in this sec- tion. In Figure 1.13 the dashed line represents the locus of the maxima of Pb versus p, with Eb/N, as a parameter. It can be seen that the value of 20 dB, for Eb/No is sufficiently high to warrant an almost linear relationship between and p, which closely conforms with the theoretically predicted line (see (1.84) and (1.85)) lim Pbmax = 0.0878p. (1.86) Eb/No->00 ED=15. Ep=20 dB Ep=2508 ED=30dB Figure 1.13. P versus p for FH/QASK-16 in noise jamming with Eb/No = 20 dB. Performance of FH/PN/QPSK in the Presence of Partial-Band Multitone Jamming ED=9db Pwc 0.6 Eg=12 de No = 12 Ep=15 dB Eb/Ny, dB Figure 1.14. Worst case p versus E/Nj-FH/QASK-16 (noise jamming). Pomax to- 308 ED=00 Eb/N,,dB Figure 1.15. Worst case Pb versus E,IN,-FH/QASK-16 (noise jamming). 1.5 PERFORMANCE OF FH/PN/QPSK IN THE PRESENCE OF PARTIAL-BAND MULTITONE JAMMING When a pseudonoise (PN) balanced modulation is superimposed on an FH/QPSK signal, each jammer tone of power J is then spread over a band- width equal to the PN chip rate Rc. Let Rs = 1/Ts be the information symbol Coherent Modulation Techniques rate and RJRs represent the processing gain associated with the PN spread- ing, herein taken to be a larger integer I. It follows from the assumption of a large processing gain that the spread tone jammer possesses a fairly flat power spectral density within the data modulation bandwidth and is now caused to behave like a white noise jammer of spectral density (1.87) Using (1.4) and (1.5), we can rewrite (1.87) as N' = J/pNR.c (1.88) Since the hop frequency slots (assumed to be contiguous) must now be R wide to accommodate the PN modulation, in terms of the total hop fre- quency band Wss and the number of hop slots N in that band, we then have N = Wss/Rc. (1.89) Co