360° bonding

Bonding all around the perimeter of a cable shield or around the periphery of an aperture in a shielded enclosure

Adjacent channel interference

Radio interference located close in frequency to the operating channel of a victim receiver

ADC

Analogue-to-digital converter

ADF

Automatic direction finding

ADSL

Asymmetrical Digital Subscriber Line - a method of delivery of broadband data over telephone lines

AM

Amplitude modulation

Amps/metre or A/m

A unit for the measure of magnetic field strength

ASIC

Application Specific Integrated Circuit

B

Magnetic flux density (units: Tesla)

BBC

British Broadcasting Corporation

Bluetooth

A wireless technology for the short-range interconnection of ITE, operating around 2.45GHz

Bonding

In EMC terms, the electrical connection of two or more conducting structures together to allow a current path and equalise their potential

CAA

Civil Aviation Authority

CAD

Computer aided design

CB

Citizen's band, a radio communications system operating around 27MHz

CCIR

International Radiocommunications Consultative Committee

CCITT

International Telegraph and Telephone Consultative Committee

CCTV

Closed circuit television

CE Mark

A mark affixed to products marketed in the EU, showing that equipment complies with applicable EU Directives

CEN

European Committee for Standardization

CENELEC

European Committee for Electrotechnical Standardization

Characteristic impedance

The ratio of voltage to current of a conducted RF signal, on a matched transmission line

CISPR

International Special Committee for Radiofrequency Interference (sub-committee of IEC)

CM

See: Common mode

CMR

Common mode rejection

Coaxial cable

Form of cable construction in which the inner conductor is surrounded by a tubular screening sheath on the same axis

Co-channel interference

Radio interference located on the same frequency as the operating channel of a victim receiver

Common mode

A voltage or current that applies identically, that is with the same polarity, to all the conductors (including return conductors and shields) within a cable, or within a given circuit: cf. differential mode. Sometimes known as asymmetrical mode

COTS

Commercial-off-the-shelf - typically describes equipment procured for specialist applications such as defence, aerospace or marine but which is only intended, certified and marketed for commercial use.

Declaration of Conformity (EU)

A document created and signed by a manufacturer or importer into the EU, which specifies the compliance of equipment with applicable EU Directives. Mandatory for all CE marked products

Detector

Radio receiver function which determines how a modulated signal is measured

Diathermy

A medical technique involving the heating of body tissue by the application of RF energy

Differential mode

A voltage or current that applies between pairs of conductors (signal and return, or power and return) within a cable, or within a given circuit: cf. common mode. Sometimes known as symmetrical mode

Disturbance

Unwanted EM energy, which may or may not affect victim equipment. Disturbances may be produced by either intentional or spurious sources, from equipment, or by natural causes (e.g. lightning, or electrostatic discharge

EC

European Commission

EEA

European Economic Area

Electromagnetic Compatibility (EMC)

The ability of an equipment or system to function satisfactorily in its electromagnetic environment without introducing intolerable electromagnetic disturbances into that environment

Electromagnetic environment

The totality of the electromagnetic phenomena existing at a particular location

Electrostatic discharge (ESD)

A sudden transfer of static electric charge from one body to another. The equalization of the charge causes transient disturbing currents and electric fields, which can create malfunctions in susceptible equipment

EM

Electromagnetic

EMC

See Electromagnetic Compatibility

EMF

Electromagnetic fields

EMI

Electromagnetic interference

EN

European Norm/European Standard, a technical document produced by CEN, CENELEC or ETSI

ERP

Effective radiated power

ETSI

European Telecommunications Standards Institute

EU

European Union

FAA

Federal Aviation Administration (USA)

Far field

Further than a certain distance (approximately one-sixth of a wavelength) from an emitting source: see Far field coupling

FCC

Federal Communications Commission (USA)

FM

Frequency modulation

Frequency

The rate at which a repetitive event happens, measured in Hertz (or kHz, MHz or GHz) (previously cycles per second)

GHz

GigaHertz: 1,000,000,000 Hertz

GPS

Global Positioning System, a network of low-earth-orbit satellites created and maintained by the US military for world-wide navigational purposes

Grounding

In EMC terms, the interconnection of conducting structures to present a low impedance reference for signal or filtering circuits. An EMC ground may or may not be at the potential of the earth mass, and is not necessarily the same as the safety earth or protective conductor

GSM

Global System for Mobile communication: the most common pan-European mobile phone system; the acronym refers both to the service and to the technical specification which underlies it

Harmonics

Frequencies which are an integer multiple of the fundamental frequency

H

Magnetic field strength (units: Amps per metre)

Hz

Hertz: unit of frequency, one cycle per second

HF

High frequency (3MHz - 30MHz)

Interference

The result of inadequate immunity to disturbances

Intermodulation

The interaction of signals at multiple frequencies in a non-linear device or environment, which generates frequencies that were not present in the original sources

I

Current

IC

Integrated circuit

IEC

International Electrotechnical Commission

IF

Intermediate frequency

IGBT

Insulated Gate Bipolar Transistor

I/O

Input/output

Induction

Coupling into a circuit by electric or magnetic fields, in the near field

ISDN

Integrated Services Digital Network

ISM

Industrial, scientific and medical

Isotropic

Radiating equally in all directions

ITE

Information technology equipment

ITU

International Telecommunications Union

kHz

kiloHertz: 1,000 Hertz

LCL

Longitudinal Conversion Loss - a measure of the conversion between differential and common mode in balanced cable pairs

LED

Light emitting diode

LF

Low frequency (30kHz - 300kHz)

LISN

Line Impedance Stabilising Network (for conducted emissions measurements)

LORAN-C

Long range navigation system

MF

Medium frequency (300kHz - 3MHz)

MHz

MegaHertz: 1,000,000 Hertz

NATS

National Air Traffic Services (UK)

Near field

Within a certain distance (approximately one-sixth of a wavelength) from an emitting source: see near field coupling

OJEU

Official Journal of the European Union

PC

Personal computer

PCB

Printed circuit board

PEC

Parallel Earth Conductor

PED

Passenger electronic device / Portable electronic device (in the context of civil airliners)

Permeability

Ratio of magnetic flux density in a medium to the magnetic field strength (µ = B/H)

Permittivity

Ratio of electric flux density in a medium to the electric field strength (Farads per metre)

PLC

Power line communications, an alternative acronym for PLT

PLL

Phase Locked Loop

PLT

Power line telecommunications - a method of delivery of broadband data over power supply lines

PMR

Private Mobile Radio

PWM

Pulse width modulation

Q

The "quality factor" of a resonance, the ratio of the frequency at the peak to the bandwidth at its -6dB points

Radiated emissions

Energy transmitted as EM waves

RAKE

Radio activated key entry (generally, keyfobs for vehicles)

Resonance

Frequency-selective phenomenon in which a peak in response or coupling is experienced around a particular frequency

RF

Radio frequency

RF bonding

In EMC terms, the electrical connection of two or more conductors together to equalise their potential at RF

RFI

Radio frequency interference

Saturation

Magnetic effect within a permeable core material, whereby the material loses its permeability if the magnetic flux density is too high

Screening

An alternative term for shielding

Shielding

The use of conducting material to form a barrier to EM waves, so that they are reflected or absorbed

Transient

A rapid change of the waveshape of voltage, current, or field, of very short duration followed by a return to steady state

Transmission line

A metallic communication in which the characteristic impedance of the conductor pair is maintained at a particular value

SMPS

Switched mode power supply

STI

Surface transfer impedance

SWA

Steel wire armoured (cable)

TEM

Transverse electromagnetic mode

TETRA

Trans European Trunked Radio Access - a digital pan-European private mobile radio system

THD

Total harmonic distortion

T-PED

Transmitting PED

TTE

Telecommunications terminal equipment

UHF

Ultra-high frequency (300 -3000MHz)

V

Volts

VCCI

Voluntary Council for Control of Interference (Japan)

VDSL

Very high speed Digital Subscriber Line (see ADSL)

VDU

Visual display unit

VHF

Very high frequency (30 -300MHz)

V/m (Volts per metre)

Measure of electric (electromagnetic) field strength

VSD

Variable speed drive. Also known as ASD (Adjustable speed drive). A motor drive using switched-mode power conversion techniques to generate a PWM output to control the rotational speed of an electric motor

VSWR

Voltage standing wave ratio

Wave impedance

The ratio of electric field to magnetic field at a point in space

Wavelength

Distance between adjacent peaks of an EM wave: related to frequency by: wavelength (metres) = 300 / frequency (MHz)

Wi-Fi

A wireless technology for the short-range interconnection of ITE, operating around 2.45 and 5GHz