3C Test Limited

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.

ADF

Automatic direction finding.

ADSL

Asymmetrical Digital Subscriber Line is 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.

ASD

Adjustable speed drive

B

Magnetic flux density.

Bluetooth

A wireless technology for the short-range interconnection of ITE, operating around 2.45GHz, originally intended as a cable replacement for printers, keyboards, and other PC peripherals.

Bonding

In EMC terms, the electrical connection of two or more conductors together to 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, at a point on the conductor.

CISPR

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

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 to all the conductors (including return conductors and shields) associated with a cable, or with an item of equipment.

Conducted (emissions, transients)

Unwanted energy conducted from equipment via the power supply or signal cables.

COTS

Commercial-off-the-shelf 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 makes various legal statements concerning the compliance of an equipment with applicable EU Directives. Mandatory for all CE marked products.

Demodulation

Recovery of the original information (speech or data) that was modulated onto a radio frequency signal.

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).

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).

dop

The latest date of publication of an identical national standard.

dow

The latest date of withdrawal of a conflicting national standard.

DTI

Department of Trade and Industry (UK).

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 dissipation of the charge causes transient disturbing currents and electric fields, which are a source of wideband radiated emissions.

EM

Electromagnetic.

EMC

See Electromagnetic Compatibility

EMF

Electromagnetic fields.

EMI

Electromagnetic interference.

EM wave

The direction of the energy transfer by an EM field.

EN

European Norm/European Standard, a technical document written 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.

FCC

Federal Communications Commission (USA).

Filter

A capacitor, inductor or resistor, or some combination of capacitors, inductors and/or resistors, intended to reduce the amount of electromagnetic energy at unwanted frequencies from being conducted along a cable or wire.

FM

Frequency modulation.

Frequency

The rate at which a repetitive event happens, measured in Hertz (or kHz, MHz or GHz).

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.

GTEM cell

An enclosed transmission line structure used for EMC testing.

Harmonics

Frequencies which are an integer multiple of the fundamental frequency.

H

Magnetic field strength.

Hz

Hertz: unit of frequency, one cycle per second.

HF

High frequency (3MHz -30MHz).

HSE

Health & Safety Executive (UK).

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 (the silicon chip)

IEC

International Electrotechnical Commission.

IEE

Institution of Electrical Engineers.

IEEE

Institution of Electrical and Electronic Engineers.

IF

Intermediate frequency.

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.

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).

LORAN-C

Long range navigation system.

LPRA

Low Power Radio Association.

MF

Medium frequency (300kHz -3MHz).

Metallic

Using a conductive method to transfer EM energy or signals (e.g. metallic communications as distinct from wireless communications).

MHz

MegaHertz: 1,000,000 Hertz.

Mode stirred chamber

A screened chamber used for EMC testing in which the EM field is made uniform by a rotating metal or metallized paddle.

NATS

National Air Traffic Services (UK).

Near field

Within a certain distance (approximately one-sixth of a wavelength) from an emitting source.

NRPB

The National Radiological Protection Board.

OATS

Open area test site.

OJEC

Official Journal of the European Communities.

PC

Personal computer.

PCB

Printed circuit board.

PED

Passenger electronic device (in the context of civil airliners).

PLC

Power line communications, an alternative acronym for PLT, see below.

PLT

Power Line Telecommunications or Power Line Technology - a method of delivery of broadband data over power supply lines.

PMR

Private Mobile Radio.

PWM

Pulse width modulation.

Q

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

Radiated emissions

Energy transmitted as EM waves.

RA

Radiocommunications Agency (UK).

RAKE

Radio activated key entry (generally, keyfobs for vehicles).

Resonance

Frequency-selective phenomenon in which a peak in response or coupling is experienced around one or more particular frequencies.

Reverberation chamber

A screened chamber used for EMC testing in which the EM field is made uniform by a rotating metal or metallized paddle.

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.

RIS

The RAs Radio Investigation Service.

RSGB

The Radio Society of Great Britain.

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 is maintained at a particular value.

SMPS

Switched mode power supply.

STI

Surface transfer impedance.

TEM

Transverse electromagnetic mode.

TETRA

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

THD

Total harmonic distortion.

TTE

Telecommunications terminal equipment.

UHF

Ultra-high frequency (300-3000MHz).

V

Volts.

VCCI

http://www.vcci.jp/vcci_e/index.html

VDSL

Very high speed Digital Subscriber Line (see ADSL).

VDU

Visual display unit.

VFD

A type of VSD in which the PWM output creates a variable frequency sine wave to control the speed of an AC motor.

VHF

Very high frequency (30-300MHz).

Volts per metre (V/M)

Measure of electric (electromagnetic) field strength.

VSD

Variable speed drive. Also known as ASD. 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 of a radiating RF signal, 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.

Wireless

Using a radiated method to transfer EM energy or signals (e.g. wireless communications as distinct from metallic communications).

Zigbee

A wireless technology for the short-range communication of data and control signals.