RF circuits x(tI cos(ot) 力、x(cos(01)-y(s(0。0 y(t) Carrie s(@t) FIGURE 69.2 Generalized transmitter using the quadrature generation technique. 团等 a(intermediate Baseband Detector amplifier (to speaker CRT, etc.) FIGURE 69.3 Superheterodyne receiver. If the complex envelope g(t) is desired for generalized signal detection or for optimum reception in digital systems,the x(n) yt) quadrature components, where x(r)+ iy(t=g(t), may be obtained by using quadrature product detectors, as illustrated in Fig. 69.4. x(n) and yr) could be fed into a signal processor to extract the modulation information. Disregarding the effects of noise, the signal processor could recover m(r)from x(t) and y(t(and, consequently, demodulate the IF signal)by using the inverse of the complex envelope generation functions given in Table 69.1 PCM= pulse-code modulation DM= differential modulation DPCM=differential pulse-code modulation FSK= frequency-shift keying PSK= phase-shift keying DPSK= differential phase-shift keying MPSK= M-ary phase-shift keying QAM= quadrature amplitude modulation c 2000 by CRC Press LLC© 2000 by CRC Press LLC If the complex envelope g(t) is desired for generalized signal detection or for optimum reception in digital systems, the x(t) and y(t) quadrature components, where x(t) + jy(t) = g(t), may be obtained by using quadrature product detectors, as illustrated in Fig. 69.4. x(t) and y(t) could be fed into a signal processor to extract the modulation information. Disregarding the effects of noise, the signal processor could recover m(t) from x(t) and y(t) (and, consequently, demodulate the IF signal) by using the inverse of the complex envelope generation functions given in Table 69.1. The generalized modulation techniques are shown in Table 69.1. In digital communication systems, discrete modulation techniques are usually used to modulate the source information signal. Discrete modulation includes: • PCM = pulse-code modulation • DM = differential modulation • DPCM = differential pulse-code modulation • FSK = frequency-shift keying • PSK = phase-shift keying • DPSK = differential phase-shift keying • MPSK = M-ary phase-shift keying • QAM = quadrature amplitude modulation FIGURE 69.2 Generalized transmitter using the quadrature generation technique. FIGURE 69.3 Superheterodyne receiver