 the basic uncoded FH/BFSK system. For simplic- ity, assume the receiver's PN sequence generator is synchronized with that of the transmitter and, thus, frequency dehop at the receiver removes the effects of the pseudorandom frequency shifts. A conventional non-coherent BFSK receiver follows the frequency dehop. Essentially, the transmitted sig- nal is a conventional BFSK signal that has a shifting carrier frequency and the receiver has a conventional BFSK receiver that merely shifts its center frequency together with that of the transmitter. The outputs of the energy detectors in Figure 3.23 are denoted e+ and e_. If there were no jamming signal present and if d = 1 were transmitted, these outputs would be e_ = 0 and e+ = ST the BFSK pulse energy. In general, the non-coherent decision rule based on the additive white Gaussian noise channel [8] is (3.75) e+se. During any Tb second interval, the transmitted signal is a tone of dura- tion Tb seconds and has a (sin2x)/x2 spectrum of bandwidth roughly 2/Tb cen- tered at frequency wo + Wn. The transmitted signal would then be one of two possible tones separated in frequency by 2Aw. This "instantaneous band- width" is generally a small fraction of the total spread-spectrum signal bandwidth Wss, which is primarily determined by the range of frequency shift values generated by the frequency hopping. For each T second interval, the particular bit error probability is deter- mined by the amount of jammer power in the "instantaneous bandwidth" of the signal that contributes to the energy terms e+ and e_. The overall bit error probability is then the average of these particular bit error probabili- ties where the average is taken over all frequency-hopped shifts. 3.6.1 Constant Power Broadband Noise Jammer Assume that the jammer transmits broadband noise over the total spread- spectrum band with constant power J. Thus, dring any Tb second interval, regardless of the carrier frequency shift, there will be an equivalent white Gaussian noise process in the "instantaneous bandwi