EFTA (European Free Trade Association), Entity Relationship Diagrams, software, E1 mutiplexers see TDM 22/16, 22/17 E layer/region, 9/3-5, 9/6, 27/6, 27/8 EIA (Electronics Industries Association), Entropy analysis, maximum, 4/7 see also lonosphere 22/24, 22/25 Entropy coding, 57/25 E-mail, 38/4 EIR (Equipment Identity Register), Entropy and information, 4/3-9 E-net (Enhanced Network), DMS, 32/19 cellphone, 47/10, 47/14 ENVs (European pre-standards), 22/21, E-region see Ionosphere EIRP (Effective Isotropically Radiated 22/23 Early Bird satellite, 11/14 Power), 6/10-11, 6/14 EOC (Embedded Operations Channel), Earphones, 58/12 EISCAT radar antenna, ionospheric Ears, 8/5-6 probing, 9/7 Equalisation, see also Hearing; Sound EKRAN satellite, 51/18 digital transmission, 19/3-4 Earth calling, PABXs, 34/6 Electric shock, 23/5 FDM repeaters, 20/21 Earthing, safety, 23/7-8 Electric to magnetic field ratio, cluttered modems, 39/11 Earth's curvature, microwave effects, 50/3 environments, 6/24 Equilibrium queue distribution, 3/13, 3/14 EBIT (European Broadband Interconnect Electric vectors, waves, 6/3 Equivalent noise resistance, 10/11 Trial), 11/9 Electricity Factories Act, 24/15 ER (Errored Seconds) measurement, EBU/SMPTE D1 digital format, 57/12 Electricity Supply Regulations (IEE), 61/9-10 ECC (Error Control Coding) see 24/15 Erbium doped fibre amplifiers, 42/27 Codes/coding Electromagnetic induction, 23/16 ERC (European Radio Committee), 22/16 Echoes, Electromagnetic waves, Erlang's lost calls equation, 5/3-13, cancellation with modems, 39/5-6, 44/12 boundary conditions, 6/4-6 29/16-17, 31/8-9, 49/4 digital transmission, 28/6 electromagnetism fundementals, 6/3 ERMES (European Radio Messaging four wire telephone circuits, 29/9-10, Fresnel diffraction, 6/6-7 Service), 11/9, 45/16-17 30/5-7, 30/9 generation and radiation, 6/7-12 ERP (Effective Radiated Power), 6/10-11, multipoint systems, 52/12 Huygen's principle, 6/6 propagation, 6/7 Error bursts in channels, 4/10 PCNs, control with, 48/9 reception, 6/12-13 Error conditions