ar, 8/5 Partial response codes, 28/11 self supporting cables, 15/15 OTRD (Optical Time Domain Partition noise, 10/11 silica glass, 53/5 Reflectometer), 15/16 Pascal programming language, 25/12-13 Snell's law of refraction, 53/8 Out-of-band (outband) signalling, 31/8, Pascal (unit of sound), 8/3 splicing, 53/6 Patch panels, 33/6 submarine cables, 15/16, 53/24 Out-of-octet signalling, TDM, 21/5 Path availability, microwaves, 50/5-6 synchronous systems, 53/25 Outage, millimetre systems, 50/8-10 Path clearance, microwave systems, systems, 53/22-4 Outsourcing, 11/16 50/3-5 transmitters, 53/18-19 Over the horizon communications, Path loss, TV distribution, 57/21, 57/23 27/13-14 cellphones, 47/6 Optical interfaces, SDH, 42/27 Over-the-horizon radar, 9/7 microwaves, 50/5 Optical links to subscribers, 15/16 Overflow bytes, SDH, 42/9 Path profiles, microwaves, 50/5 Optical power meters, 7/7-8 Overlay paging, 45/15 PAX (Private Automatic Exchange), 29/6 Optical switching, 42/27 Overload, FDM transmissions, 20/15-16 Pay per view TV, 57/19 Optics and vision, PBA (Printed Board Assembly), absorption, 7/12 P service priority service, 25/6 System 12, 32/12 human eye, 7/9-11 p-i-n photodetector, 53/14-17 PBX (Private Branch Exchange), 31/6 Index/16 Centrex comparison, 35/3 SAMs (Separate and Multiplication), queue arrival, 3/8-9, 3/12 PCA (Polar cap absorption), 9/4 53/16 queuing theory, 3/5-6 PCM (Pulse code modulation), 19/11-18, Si, 53/16 Polarisation, Photofax equipment, 60/3-4 circular, 6/11, 17/4 digital networks, 29/10-12 see also Facsimile (Fax) coupling loss, 6/20-1 digital switching, 31/13-14 Photometers, 7/6 elliptical, 6/11-12 digital video, 57/23-4 Photometry, 7/3-9 axial ratio, 6/12 distortion, 30/5 Photopic eye response, 7/3-4 ellipticity angle, 6/12 information theory, 4/12 Physical layer, OSI, 12/10 orientation angle, 6/12 measurements, 61/3 Pictograms, 1/3 sense of rotation, 6/12 multipoint systems, 52/8 PID (Protocol Identifier), PMR, 46/12 ground waves, L.F. and M.F., 27/6 networking with, 56/4-5 Pie charts, 1