d as additive white Gaussian noise of single-sided spectral density No. With this receiver noise included in the analysis, the resulting bit error probability would have the form Ph=f(E,/N,,E/No) (3.90) which is a function of the bit energy-to-noise ratio, E/No, as well as the effec- tive bit energy-to-jammer power density ratio, Eb/N, defined in (3.3). The examples illustrated in this chapter assumed No = 0 or E/ = 8, which is equivalent to assuming the jammer interference is much stronger than the receiver noise which can then be ignored. This resulted in bit error probability expressions of the form (3.91) which were derived in this chapter for a few simple examples. Of course, if Receiver Noise Floor Figure 3.27. Interleaver for FH/BFSK. Basic Concepts and System Models the jammer is not transmitting (N) = 0), then the impact of receiver noise must be considered since it is no longer negligible. Here, (3.92) can be obtained using conventional performance analysis for the additive white Gaussian noise channel [8]. Figure 3.28 illustrates the typical relationship between P, P, and the exact bit error probability . The overall analysis is considerably simplified by examining separately the performance as a result of jamming alone and then as a result of noise alone, since the exact bit error probability is approx- imately the larger of these two bit error probabilities. The additive white Gaussian noise, n(t), is sometimes referred to as the receiver noise floor implying that it sets the lower limit on the bit error prob- ability when considering other types of channel interference. The analysis P*=1(ED/NJ,00) Eb/No = fixed Noise Floor Error E/// (dB) Figure 3.28. Impact of receiver noise. References presented here and in Part 1, Chapter 4, and Part 2, Chapters 1 and 2, ignores this receiver noise and considers the impact of the jammer alone. Some receiver noise floor, as illustrated in Figure 3.28, will always exist and must ultimately be considered. We are primarily concerned with the impact of jam- ming which