ctronIc scillator Control Binary data input m(t) (a)Discontinuous-Phase FSK Binary m(t) FSK (carrier freq. =fcl FIGURE 69.6 Generation of FSK FSK in Frequency Output FSK in detecto cos(o,t) (a) Noncoherent Detection (b)Coherent(Synchronous) Detection FIGURE 69.7 Detection of FSK where the permitted values of x and y are OS yi=A sin 8. (69.11) for the permitted phase angles 0, i= 1, 2,, M, of the MPSK signal. This is illustrated by Fig 69.8, where the ignal processing circuit implements Eqs. (69.10)and(69.11) MPSK, where M=4, is called quadrature-phase-shift-keyed(QPSK) signaling Quadrature Amplitude Modulation Quadrature carrier signaling is called quadrature amplitude modulation(QAM). In general, QAM signal constellations are not restricted to having permitted signaling points only on a circle(of radius A, as was the ase for MPSK). The general QAM signal is s(t)=x(r) cos o,t-y(t) sin o t (69.12) c 2000 by CRC Press LLC© 2000 by CRC Press LLC where the permitted values of x and y are xi = Ac cos qi (69.10) yi = Ac sin qi (69.11) for the permitted phase angles qi , i = 1, 2, ..., M, of the MPSK signal. This is illustrated by Fig. 69.8, where the signal processing circuit implements Eqs. (69.10) and (69.11). MPSK, where M = 4, is called quadrature-phase-shift-keyed (QPSK) signaling. Quadrature Amplitude Modulation Quadrature carrier signaling is called quadrature amplitude modulation (QAM). In general, QAM signal constellations are not restricted to having permitted signaling points only on a circle (of radius Ac, as was the case for MPSK). The general QAM signal is s(t) = x(t) cos wct – y(t) sin wct (69.12) FIGURE 69.6 Generation of FSK. FIGURE 69.7 Detection of FSK