O/MPEG Draft International 26/17-18 Unloaded circuits, modem use, 39/9-10 Standard 11172, 57/28 satellite, 51/13, 51/18 UNMA, AT&T, 56/6 motion compensation, 57/26-7 VSB (Vestigial Sideband Modulation), UPS (Uninterruptible Power Supplies), PCM, 57/23-4 18/6-7, 19/7, 57/19 24/7-8 sub-band, 57/26 VSWR (Voltage Standing Wave Ratio), UPs (User Parts), AXE system, 32/16 transform, 57/25-6 17/12 Urban multipoint systems see Radio variable length, 57/25 VT (Virtual Terminal), OSI, 16/11 multipoint systems vector quantisation, 57/26 VT (Virtual Tributary), SONET, 42/17 US CCITT, 22/23-4 wavelet, 57/29 US Department of State, ITU conferencing, 44/13, 57/27 Walk throughs, software testing, 25/14 representation, 22/23 digital audio, 57/15-16 Walk time, polling, 13/16 digital video, 57/12-16 Wander TDM timing faults, 21/12 paging frequencies, 45/4 modulation techniques, 57/20 measurement, 61/6-7 telecommunications industry, 11/6-7 multiplexing, 40/8 WANs (Wide Area Networks), 13/3, User-network signalling, 43/10-11 networks, 57/19-20 16/20, 56/4, 56/11-17 Utilisation factor, multiple access, 13/4-5 optical fibre transmission, 57/21, 57/23 fast packet switching with, 55/6 UTP (Unshielded Twisted Pair) cable, performance standards, 57/22-3 packet switching with, 54/4 33/4-5, 33/6 SDH multiplexing, 42/15-16 see also LANs; Networks/networking fault symptoms, 33/7 storage, 57/26 WARC (World Administrative Radio V.24 modems, 39/8-9 teletex, 57/14 Conference), 22/7, 26/14 Index/25 WATTC (World Administrative 20/12 XPD (Cross polarisation discrimination), Telephone and Telegraph Conference), Weighting networks, sound, 8/7 6/19-20 Whistler dispersions, 9/9 Yagi antenna, 6/13 Waveform shaping, digital transmission, White pages protocols, 16/5 Yellow page protocols, 16/5 White-box software testing, 25/15-16 Yourdon structured software design, 25/5 Waveguide antenna feed systems, 17/13 Wind power generation, 24/3-4 YUV television signals, 57/5, 57/7 Waveguide dispersion, optical cables, 53/7 Window flow control, transmission links, Wav