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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 – 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 see VSD.
B Magnetic flux density.
BBC British Broadcasting Corporation.
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).
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 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 (also “detection”).
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.
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.
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.
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.
NATS National Air Traffic Services (UK).
Near field Within a certain distance (approximately one-sixth of a wavelength) from an emitting source.
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 – 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.
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.
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 RA’s 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 Voluntary Council for Control of Interference (Japan).
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 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.