(DE) indicator bit, 331, 333, 511 digital modulation, of LOS microwave radios, 208-211 disciplined oscillators, 140 digital networks, 107-147. See also digital disconnect timing, 166 discrete cosine transform, 426 switching data transmission on, 277-278 discrete states, in digital signals, 107 digital loop carrier, 128 dispersion, 60-61, 243 higher-order PCM multiplex systems, 122-126 diversity technique for, 465-467 line code and, 119-120 dispersion-limited fiber-optic link, 233-234 long-distance PCM transmission, 126-128 dispersion-limited fiber-optic systems, 35 loss plan for, 193 dispersion shifting, 242 PCM system enhancements, 122 dissipation loss, hybrid device, 77 PCM system operation, 118-119 distance limitations, baseband transmission, 28 performance requirements of, 142-145 distance metric, 323-324 pulse code modulation and, 108-118 distortion, in long-distance PCM transmission, 127 regenerative repeaters and, 121-122 distribution, of calls, 71f signal-to-Gaussian-noise ratio on PCM distribution curves, 60-61 repeatered lines, 120 DIUC (downlink interval usage code), 353 slips (impairment) in, 138-139 diversity, 214, 215-216 technical requirements of, 137-142 diversity technique, for fading and dispersion, digital radio systems, calculation of Eb/No in, 207 465-467 digital signaling data link, 367, 368 DL-MAP message, 354 digital signals DMS-100 switch, 135, 136f binary, 29-31 with supernode/ENET, 136-137 information content of, 107 DNHR (dynamic nonhierarchical routing), 13 digital subscriber line (DSL), 90 DOCSIS (Data over Cable Service Interface new versions of, 128 Specification), 450, 451-454 remote subscriber unit and, 170, 171f data-link layer, 453-454 digital switches. See also digital switching physical layer, 452-453 architecture of, 129-135 DOCSIS 2.0 specification, two-way voice and data automatic controls in, 552-553 over CATV systems based on, 451-454 higher-level multiplex structures in, 136-137 DOCSIS networks, 452, 453f digital switching, 128-137 dot, Morse code, 22 advantages and iss