/3 ionospheric effects, 9/5 PABXs, 34/4 Piezo-electric telephone transmitters, 58/4 light, 7/12 PCM-30, 21/9-12 Pilots, FDM, 20/8-9 linear, 6/11, 17/4 receiver interference, 58/7 Planck's constant, 53/9 waves, 6/5-6 signalling, 43/7 Planning see Transmission planning Polarisation-diversity receivers, 9/6 PCNs (Personal Communication Plante battery cells, 24/12-13 Poles, frequency response diagram, 2/15 Networks), Plasma frequency, 9/5 Pollazcek-Kinchine formula, 3/11 AXE system, 32/18 PLEX (Programming Language for Polling, background, 48/3-4 Telephone Exchanges), AXE system, multiple access, 13/16-17 coding and control, 48/8-9 32/14 protocols, 40/6 design, 48/9-10 PLL (Phase Locked Loop), Polychromatic light, 7/6 microcells, 48/11 AM demodulator, 18/4 Polydimethyl silicone optical cable multipoint application, 52/12 FM, 18/8-9 material, 15/12 network elements, 48/4 TDM, 21/13 Polynomial notation, codes, 14/6 planning and numbering, 48/5-7 PLMN (Public Land Mobile Network), POSI (Promoting Conference for OSI), 47/14 see also Cellular radio systems 16/8, 22/26 PM (Phase Modulation), 18/7-12 Positive plate traction battery cells, 24/13 modems, 39/4-5 fax, 60/15 POSP (Private Off-Site Paging) systems, in LANs, 56/6-7 PMBX (Private Manual Branch 24/13, 45/15 Exchange), 31/6 modem connection, safety, 23/6-7 Power, cellphones, control of, 47/5 PMR (Private Mobile Radio), terminals, ISDN, 44/13 Power budgets, band III, 46/6-8 cellphones, 47/7 PDH (Plesiochronous Digital Hierarchy), base stations, 46/4, 46/6 optical fibre, 53/23 42/3-5 batteries, 46/3 Power feeding, FDM repeaters, 20/21-2 PDTC (PCM30 Digital Trunk Controller), call processing, 46/7 Power management systems, 24/14 DMS, 32/20-1 channel recognition, 46/6 Power radiated, 6/8, 6/9, 6/10-11, 27/4, PDU (Protocol Data Unit), OSI layer coverage, 46/5, 46/6 27/10 services, 12/8 digital signalling, 46/8, 46/9-10 microwave systems, 50/16 Peer entities, OSI layer services, 12/6 equipment, 46/3 satellite systems, 51/11 Peltier effect amplifiers, 51/16 packet data, 46/