Function (TRDF), 16 field Language (VRML), 60 Tributary Unit (TU), 321 VCOs. See Voltage Controlled Virtual Tributaries (VTs), 312 Tributary Unit Groups (TUGs), Oscillators Viterbi decoding, 98-100 321-325 VCs. See Virtual Containers VLANs See Virtual LANs Tropospheric refractive index Velocity in Maxwell's equations, VLF frequency, 275 effects, 243-244 Voice communication standards, Tropospheric scatter, 274 Vertical Radiation Pattern (VRP), Truewave XL Ocean fiber, 143 232-233 Voice over Internet Protocol Trunks Vertically polarized ground wave (VoIP), 8 MPLS, 378 transmissions, 263-264 Voice transmission RSVP-TE, 392 Vestigial-Sideband (VSB) multiplexing, 19-24 TT&C. See Telemetry, Tracking, Modulation, 202 PCM. See Pulse Code and Command antennas VHF antennas, 305-306 Modulation Index Voice transmission (cont'd) Wedge shapes, approximating to, speech-coding principles, 3-9 Wait-to-Restore timers, 418 241-242 transmission performance, Waiting states, 21 Weighted Fair Queuing (WFQ) 24-27 Wander buffers, 317 technique, 78 Voiced speech, 3-4 Wander effect, 51 White noise, 42 VoIP. See Voice over Internet WANs. See Wide Area Networks Wide Area Networks (WANs), Protocol, 8 WAN services, introduction, 361-363 Voltage Controlled Oscillators 361-363 generic, 364-366 (VCOs), 27 Water loss, 118 interfaces, 344 Voltage reflection coefficient, 269 Wave equations, 219-221 Wideband Gaussian noise, 42 VPI. See Virtual Path Indicator Waveform-based speech coding, Wire antennas, 302 field Word interleaving, 20 VPLS. See Virtual Private LAN Waveguide dispersion, 177 Service multimode fibers, 127 VPNs. See Virtual Private optical fibers, 118 X.25 over TCP (XOT), 369 Networks single-mode fibers, 128-131 X.25 services, 369 VRML. See Virtual Reality Waveguide feed systems, 301 XPM. See Cross-Phase Modeling Language, 60 Wavelength Division Multi- Modulation VRM-WB. See Variable-Rate plexed (WDM), 131, 183-184 Multimode Wideband chromatic dispersion, speech coding standard 184-185 Yagi-Uda arrays, 305-306 VRP. See Vertical Radiation 