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53-398: An area at Arrival Heights was originally protected because its geographical characteristics, such as its elevated position and broad viewing horizon, as well as the volcanic crater morphology, made it useful as a “quiet” (lacking electromagnetic interference ) site for atmospheric studies. It has the logistic support of McMurdo Station 1.5 km to the south, and Scott Base 3 km to

106-405: A parabolic antenna or a diversity receiver , can be used to select one signal in space to the exclusion of others. The most extreme example of digital spread-spectrum signalling to date is ultra-wideband ( UWB ), which proposes the use of large sections of the radio spectrum at low amplitudes to transmit high-bandwidth digital data. UWB, if used exclusively, would enable very efficient use of

159-650: A "shimmy" effect in each other, due to the electromagnetic nature of their picture tubes, especially when one of their de-gaussing coils is activated. Electromagnetic interference at 2.4 GHz may be caused by 802.11b , 802.11g and 802.11n wireless devices, Bluetooth devices, baby monitors and cordless telephones , video senders , and microwave ovens . Switching loads ( inductive , capacitive , and resistive ), such as electric motors, transformers, heaters, lamps, ballast, power supplies, etc., all cause electromagnetic interference especially at currents above 2  A . The usual method used for suppressing EMI

212-572: A MF-radar was installed by the Physics Department at the University of Canterbury, New Zealand to measure D-region winds in the ionosphere . Coincidentally, also in 1982 the first stratospheric trace gas remote sensing uv/vis grating spectrometer was installed by DSIR, New Zealand to measure nitrogen dioxide abundance in the polar atmosphere. With the discovery of the Antarctic ozone hole

265-526: A barrier to trade within the EC. One of these was the EMC Directive (89/336/EC) and it applies to all equipment placed on the market or taken into service. Its scope covers all apparatus "liable to cause electromagnetic disturbance or the performance of which is liable to be affected by such disturbance". This was the first time there was a legal requirement on immunity, as well as emissions on apparatus intended for

318-527: A cascade of remote sensing instrumentation was installed by the DSIR (known as NIWA from 1992) over the next 10–15 years focusing on taking measurements for stratospheric heterogeneous chemistry and ozone depletion research. In 1988 DSIR started a research programme to obtain in situ flask samples for greenhouse gas and carbon isotope analysis. Both the in situ and remote sensing measurements are an important part in global atmospheric monitoring networks such as GAW and

371-634: A combination of emissions , radiations , or inductions upon reception in a radiocommunication system, manifested by any performance degradation, misinterpretation, or loss of information which could be extracted in the absence of such unwanted energy". This is also a definition used by the frequency administration to provide frequency assignments and assignment of frequency channels to radio stations or systems, as well as to analyze electromagnetic compatibility between radiocommunication services . In accordance with ITU RR (article 1) variations of interference are classified as follows: Conducted EMI

424-607: A combination of public and private sector, and some are private sector only. About 90% of those who prepare IEC standards work in industry. IEC Member countries include: In 2001 and in response to calls from the WTO to open itself to more developing nations, the IEC launched the Affiliate Country Programme to encourage developing nations to become involved in the commission's work or to use its International Standards. Countries signing

477-643: A detector for those radio signals commonly found in the domestic environment (e.g. mobile phones). Such a detector can demodulate the high frequency mobile phone carrier (e.g., GSM850 and GSM1900, GSM900 and GSM1800) and produce low-frequency (e.g., 217 Hz) demodulated signals. This demodulation manifests itself as unwanted audible buzz in audio appliances such as microphone amplifier, speaker amplifier, car radio, telephones etc. Adding onboard EMI filters or special layout techniques can help in bypassing EMI or improving RF immunity. Some ICs are designed (e.g., LMV831-LMV834, MAX9724 ) to have integrated RF filters or

530-402: A special design that helps reduce any demodulation of high-frequency carrier. Designers often need to carry out special tests for RF immunity of parts to be used in a system. These tests are often done in an anechoic chamber with a controlled RF environment where the test vectors produce a RF field similar to that produced in an actual environment. Interference in radio astronomy , where it

583-812: A vast range of technologies from power generation, transmission and distribution to home appliances and office equipment, semiconductors, fibre optics, batteries, solar energy , nanotechnology , and marine energy, as well as many others. The IEC also manages four global conformity assessment systems that certify whether equipment, system or components conform to its international standards. All electrotechnologies are covered by IEC Standards, including energy production and distribution, electronics, magnetics and electromagnetics , electroacoustics , multimedia , telecommunications and medical technology , as well as associated general disciplines such as terminology and symbols, electromagnetic compatibility, measurement and performance, dependability, design and development, safety and

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636-436: A wavelength apart, inducing a change in voltage on the receiving conductor. Inductive coupling or magnetic coupling occurs when a varying magnetic field exists between two parallel conductors typically less than a wavelength apart, inducing a change in voltage along the receiving conductor. Radiative coupling or electromagnetic coupling occurs when source and victim are separated by a large distance, typically more than

689-610: A wavelength. Source and victim act as radio antennas: the source emits or radiates an electromagnetic wave which propagates across the space in between and is picked up or received by the victim. Interference with the meaning of electromagnetic interference , also radio-frequency interference ( EMI or RFI ) is – according to Article 1.166 of the International Telecommunication Union ' s (ITU) Radio Regulations (RR)  – defined as "The effect of unwanted energy due to one or

742-598: Is a committee of the International Electrotechnical Commission (IEC) sets international standards for radiated and conducted electromagnetic interference. These are civilian standards for domestic, commercial, industrial and automotive sectors. These standards form the basis of other national or regional standards, most notably the European Norms (EN) written by CENELEC (European committee for electrotechnical standardisation). US organizations include

795-749: Is also available as EN 60034. Standards developed jointly with ISO, such as ISO/IEC 26300 ( Open Document Format for Office Applications (OpenDocument) v1.0 ), ISO/IEC 27001 ( Information technology, Security techniques, Information security management systems, Requirements ), and ISO/IEC 17000 series, carry the acronym of both organizations. The use of the ISO/IEC prefix covers publications from ISO/IEC Joint Technical Committee 1 – Information Technology , as well as conformity assessment standards developed by ISO CASCO (Committee on conformity assessment) and IEC CAB (Conformity Assessment Board). Other standards developed in cooperation between IEC and ISO are assigned numbers in

848-449: Is as good as the other) and the length of the conductor in relation to the wavelength of the signal component ( fundamental frequency , harmonic or transient such as overshoot, undershoot or ringing). At lower frequencies, such as 133  MHz , radiation is almost exclusively via I/O cables; RF noise gets onto the power planes and is coupled to the line drivers via the VCC and GND pins. The RF

901-400: Is by connecting a snubber network, a resistor in series with a capacitor , across a pair of contacts. While this may offer modest EMI reduction at very low currents, snubbers do not work at currents over 2 A with electromechanical contacts. Another method for suppressing EMI is the use of ferrite core noise suppressors (or ferrite beads ), which are inexpensive and which clip on to

954-509: Is caused by the physical contact of the conductors as opposed to radiated EMI which is caused by induction (without physical contact of the conductors). For lower frequencies, EMI is caused by conduction and, for higher frequencies, by radiation. EMI through the ground wire is also very common in an electrical facility. Interference tends to be more troublesome with older radio technologies such as analogue amplitude modulation , which have no way of distinguishing unwanted in-band signals from

1007-526: Is caused by the physical contact of the conductors as opposed to radiated EMI, which is caused by induction (without physical contact of the conductors). Electromagnetic disturbances in the EM field of a conductor will no longer be confined to the surface of the conductor and will radiate away from it. This persists in all conductors and mutual inductance between two radiated electromagnetic fields will result in EMI. Some of

1060-453: Is commonly referred to as radio-frequency interference (RFI), is any source of transmission that is within the observed frequency band other than the celestial sources themselves. Because transmitters on and around the Earth can be many times stronger than the astronomical signal of interest, RFI is a major concern for performing radio astronomy. Natural sources of interference, such as lightning and

1113-593: Is into narrowband and broadband, according to the spread of the frequency range. An electromagnetic pulse (EMP), sometimes called a transient disturbance, arises where the source emits a short-duration pulse of energy. The energy is usually broadband by nature, although it often excites a relatively narrow-band damped sine wave response in the victim. Sources divide broadly into isolated and repetitive events. Sources of isolated EMP events include: Sources of repetitive EMP events, sometimes as regular pulse trains , include: Conducted electromagnetic interference

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1166-456: Is made up of members, called national committees, and each NC represents its nation's electrotechnical interests in the IEC. This includes manufacturers, providers, distributors and vendors, consumers and users, all levels of governmental agencies, professional societies and trade associations as well as standards developers from national standards bodies. National committees are constituted in different ways. Some NCs are public sector only, some are

1219-629: Is published online as the Electropedia . The CISPR ( Comité International Spécial des Perturbations Radioélectriques ) – in English, the International Special Committee on Radio Interference – is one of the groups founded by the IEC. Currently, 89 countries are IEC members while another 85 participate in the Affiliate Country Programme, which is not a form of membership but is designed to help industrializing countries get involved with

1272-483: Is then coupled to the cable through the line driver as common-mode noise . Since the noise is common-mode, shielding has very little effect, even with differential pairs . The RF energy is capacitively coupled from the signal pair to the shield and the shield itself does the radiating. One cure for this is to use a braid-breaker or choke to reduce the common-mode signal. At higher frequencies, usually above 500 MHz, traces get electrically longer and higher above

1325-466: The American Institute of Electrical Engineers , and others, which began at the 1900 Paris International Electrical Congress, , with British engineer R. E. B. Crompton playing a key role. In 1906, Lord Kelvin was elected as the first President of the International Electrotechnical Commission. The IEC was instrumental in developing and distributing standards for units of measurement, particularly

1378-679: The gauss , hertz , and weber . It was also first to promote the Giorgi System of standards, later developed into the SI , or Système International d'unités (in English, the International System of Units). In 1938, it published a multilingual international vocabulary to unify terminology relating to electrical, electronic and related technologies. This effort continues, and the International Electrotechnical Vocabulary

1431-617: The 21-cm line from the reionization epoch can overlap with the FM broadcast band (88–108 MHz), and therefore radio telescopes need to deal with RFI in this bandwidth. International Electrotechnical Commission The International Electrotechnical Commission ( IEC ; French : Commission électrotechnique internationale ) is an international standards organization that prepares and publishes international standards for all electrical , electronic and related technologies – collectively known as " electrotechnology ". IEC standards cover

1484-545: The 21st century by roughly one decibel per year as the spectrum becomes increasingly crowded. This has inflicted a Red Queen's race on the mobile phone industry as companies have been forced to put up more cellular towers (at new frequencies) that then cause more interference thereby requiring more investment by the providers and frequent upgrades of mobile phones to match. The International Special Committee for Radio Interference or CISPR (French acronym for "Comité International Spécial des Perturbations Radioélectriques"), which

1537-406: The 80000 series, such as IEC 82045–1. IEC Standards are also being adopted by other certifying bodies such as BSI (United Kingdom), CSA (Canada), UL & ANSI / INCITS (United States), SABS (South Africa), Standards Australia , SPC / GB (China) and DIN (Germany). IEC standards adopted by other certifying bodies may have some noted differences from the original IEC standard. The IEC

1590-680: The IEC. Originally located in London , United Kingdom, the IEC moved to its current headquarters in Geneva , Switzerland in 1948. It has regional centres in Africa ( Nairobi , Kenya), Asia ( Singapore ), Oceania ( Sydney , Australia), Latin America ( São Paulo , Brazil) and North America ( Worcester, Massachusetts , United States). The work is done by some 10,000 electrical and electronics experts from industry, government, academia, test labs and others with an interest in

1643-664: The Institute of Electrical and Electronics Engineers (IEEE), the American National Standards Institute (ANSI), and the US Military (MILSTD). Integrated circuits are often a source of EMI, but they must usually couple their energy to larger objects such as heatsinks, circuit board planes and cables to radiate significantly. On integrated circuits , important means of reducing EMI are: the use of bypass or decoupling capacitors on each active device (connected across

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1696-581: The NDACC. In 2007, the new Arrival Heights Laboratory was built. 77°49′S 166°39′E  /  77.817°S 166.650°E  / -77.817; 166.650 Electromagnetic interference Electromagnetic interference ( EMI ), also called radio-frequency interference ( RFI ) when in the radio frequency spectrum, is a disturbance generated by an external source that affects an electrical circuit by electromagnetic induction , electrostatic coupling , or conduction. The disturbance may degrade

1749-552: The Sun, are also often referred to as RFI. Some of the frequency bands that are very important for radio astronomy, such as the 21-cm HI line at 1420 MHz, are protected by regulation. However, modern radio-astronomical observatories such as VLA , LOFAR , and ALMA have a very large bandwidth over which they can observe. Because of the limited spectral space at radio frequencies, these frequency bands cannot be completely allocated to radio astronomy; for example, redshifted images of

1802-539: The earliest days of radio communications, the negative effects of interference from both intentional and unintentional transmissions have been felt and the need to manage the radio frequency spectrum became apparent. In 1933, a meeting of the International Electrotechnical Commission (IEC) in Paris recommended the International Special Committee on Radio Interference ( CISPR ) be set up to deal with

1855-491: The emerging problem of EMI. CISPR subsequently produced technical publications covering measurement and test techniques and recommended emission and immunity limits. These have evolved over the decades and form the basis of much of the world's EMC regulations today. In 1979, legal limits were imposed on electromagnetic emissions from all digital equipment by the FCC in the US in response to

1908-598: The environment. The first International Electrical Congress took place in 1881 at the International Exposition of Electricity , held in Paris. At that time the International System of Electrical and Magnetic Units was agreed to. The International Electrotechnical Commission held its inaugural meeting on 26 June 1906, following discussions among the British Institution of Electrical Engineers ,

1961-490: The general population. Although there may be additional costs involved for some products to give them a known level of immunity, it increases their perceived quality as they are able to co-exist with apparatus in the active EM environment of modern times and with fewer problems. Many countries now have similar requirements for products to meet some level of electromagnetic compatibility (EMC) regulation. Electromagnetic interference divides into several categories according to

2014-478: The increased number of digital systems that were interfering with wired and radio communications. Test methods and limits were based on CISPR publications, although similar limits were already enforced in parts of Europe. In the mid 1980s, the European Union member states adopted a number of "new approach" directives with the intention of standardizing technical requirements for products so that they do not become

2067-440: The intended signal, and the omnidirectional antennas used with broadcast systems. Newer radio systems incorporate several improvements that enhance the selectivity . In digital radio systems, such as Wi-Fi , error-correction techniques can be used. Spread-spectrum and frequency-hopping techniques can be used with both analogue and digital signalling to improve resistance to interference. A highly directional receiver, such as

2120-426: The lower path in the diagram involves inductive, conductive and capacitive modes. Conductive coupling occurs when the coupling path between the source and victim is formed by direct electrical contact with a conducting body, for example a transmission line, wire, cable, PCB trace or metal enclosure. Conducted noise is also characterised by the way it appears on different conductors: Inductive coupling occurs where

2173-679: The performance of the circuit or even stop it from functioning. In the case of a data path, these effects can range from an increase in error rate to a total loss of the data. Both human-made and natural sources generate changing electrical currents and voltages that can cause EMI: ignition systems , cellular network of mobile phones, lightning , solar flares , and auroras (northern/southern lights). EMI frequently affects AM radios . It can also affect mobile phones , FM radios , and televisions , as well as observations for radio astronomy and atmospheric science . EMI can be used intentionally for radio jamming , as in electronic warfare . Since

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2226-423: The plane. Two techniques are used at these frequencies: wave shaping with series resistors and embedding the traces between the two planes. If all these measures still leave too much EMI, shielding such as RF gaskets and copper or conductive tape can be used. Most digital equipment is designed with metal or conductive-coated plastic cases. Any unshielded semiconductor (e.g. an integrated circuit) will tend to act as

2279-571: The power lead of the offending device or the compromised device. Switched-mode power supplies can be a source of EMI, but have become less of a problem as design techniques have improved, such as integrated power factor correction . Most countries have legal requirements that mandate electromagnetic compatibility : electronic and electrical hardware must still work correctly when subjected to certain amounts of EMI, and should not emit EMI, which could interfere with other equipment (such as radios). Radio frequency signal quality has declined throughout

2332-422: The power supply, as close to the device as possible), rise time control of high-speed signals using series resistors, and IC power supply pin filtering. Shielding is usually a last resort after other techniques have failed, because of the added expense of shielding components such as conductive gaskets. The efficiency of the radiation depends on the height above the ground plane or power plane (at RF , one

2385-497: The range 60000–79999 and their titles take a form such as IEC 60417: Graphical symbols for use on equipment . Following the Dresden Agreement with CENELEC the numbers of older IEC standards were converted in 1997 by adding 60000, for example IEC 27 became IEC 60027. Standards of the 60000 series are also found preceded by EN to indicate that the IEC standard is also adopted by CENELEC as a European standard; for example IEC 60034

2438-445: The source and signal characteristics. The origin of interference, often called "noise" in this context, can be human-made (artificial) or natural. Continuous, or continuous wave (CW), interference arises where the source continuously emits at a given range of frequencies. This type is naturally divided into sub-categories according to frequency range, and as a whole is sometimes referred to as "DC to daylight". One common classification

2491-437: The source and victim are separated by a short distance (typically less than a wavelength ). Strictly, "Inductive coupling" can be of two kinds, electrical induction and magnetic induction. It is common to refer to electrical induction as capacitive coupling , and to magnetic induction as inductive coupling . Capacitive coupling occurs when a varying electrical field exists between two adjacent conductors typically less than

2544-500: The source may be a natural phenomenon such as a lightning strike , electrostatic discharge (ESD) or, in one famous case , the Big Bang at the origin of the Universe. There are four basic coupling mechanisms: conductive , capacitive , magnetic or inductive, and radiative . Any coupling path can be broken down into one or more of these coupling mechanisms working together. For example

2597-509: The south-east, and continues to be protected as Antarctic Specially Protected Area (ASPA) No.122 (est. 1975) for its value in upper atmospheric research and boundary layer air sampling studies. Upper atmospheric research started at Arrival Heights in 1959 with the establishment of an unmanned auroral radar station by the New Zealand's Department of Scientific and Industrial Research (DSIR) in partnership with Stanford University (USA). This

2650-901: The spectrum, but users of non-UWB technology are not yet prepared to share the spectrum with the new system because of the interference it would cause to their receivers (the regulatory implications of UWB are discussed in the ultra-wideband article). In the United States , the 1982 Public Law 97-259 allowed the Federal Communications Commission (FCC) to regulate the susceptibility of consumer electronic equipment. Potential sources of RFI and EMI include: various types of transmitters , doorbell transformers, toaster ovens , electric blankets , ultrasonic pest control devices, electric bug zappers , heating pads , and touch controlled lamps . Multiple CRT computer monitors or televisions sitting too close to one another can sometimes cause

2703-632: The subject. IEC Standards are often adopted as national standards by its members. The IEC cooperates closely with the International Organization for Standardization (ISO) and the International Telecommunication Union (ITU) . In addition, it works with several major standards development organizations, including the IEEE with which it signed a cooperation agreement in 2002, which was amended in 2008 to include joint development work. IEC Standards that are not jointly developed with ISO have numbers in

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2756-449: The technical terms which are employed can be used with differing meanings. Some phenomena may be referred to by various different terms. These terms are used here in a widely accepted way, which is consistent with other articles in the encyclopedia. The basic arrangement of noise emitter or source, coupling path and victim, receptor or sink is shown in the figure below. Source and victim are usually electronic hardware devices, though

2809-399: Was to coincide with other Antarctic atmospheric research activities as part of the 1957 IGY programme including the establishment of a full geomagnetic observatory, vertical incident ionosonde station and AZA transmitter at Scott Base. Over the next 10–15 years a variety of additional DSIR equipment was added, including an auroral camera along with American scientific investigations. In 1982

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