International Organization for Standardization
The International Organization for Standardization is an international standard-setting body composed of representatives from various national standards organizations. Founded on 23 February 1947, the organization promotes worldwide proprietary and it is headquartered in Geneva, and as of March 2017 works in 162 countries. It was one of the first organizations granted general consultative status with the United Nations Economic, ISO, the International Organization for Standardization, is an independent, non-governmental organization, the members of which are the standards organizations of the 162 member countries. It is the worlds largest developer of international standards and facilitates world trade by providing common standards between nations. Nearly twenty thousand standards have been set covering everything from manufactured products and technology to food safety, use of the standards aids in the creation of products and services that are safe, reliable and of good quality. The standards help businesses increase productivity while minimizing errors and waste, by enabling products from different markets to be directly compared, they facilitate companies in entering new markets and assist in the development of global trade on a fair basis.
The standards serve to safeguard consumers and the end-users of products and services, the three official languages of the ISO are English and Russian. The name of the organization in French is Organisation internationale de normalisation, according to the ISO, as its name in different languages would have different abbreviations, the organization adopted ISO as its abbreviated name in reference to the Greek word isos. However, during the meetings of the new organization, this Greek word was not invoked. Both the name ISO and the logo are registered trademarks, the organization today known as ISO began in 1926 as the International Federation of the National Standardizing Associations. ISO is an organization whose members are recognized authorities on standards. Members meet annually at a General Assembly to discuss ISOs strategic objectives, the organization is coordinated by a Central Secretariat based in Geneva. A Council with a membership of 20 member bodies provides guidance and governance.
The Technical Management Board is responsible for over 250 technical committees, ISO has formed joint committees with the International Electrotechnical Commission to develop standards and terminology in the areas of electrical and electronic related technologies. Information technology ISO/IEC Joint Technical Committee 1 was created in 1987 to evelop, maintain, ISO has three membership categories, Member bodies are national bodies considered the most representative standards body in each country. These are the members of ISO that have voting rights. Correspondent members are countries that do not have their own standards organization and these members are informed about ISOs work, but do not participate in standards promulgation. Subscriber members are countries with small economies and they pay reduced membership fees, but can follow the development of standards
In computing, floating-point arithmetic is arithmetic using formulaic representation of real numbers as an approximation so as to support a trade-off between range and precision. A number is, in general, represented approximately to a number of significant digits and scaled using an exponent in some fixed base. For example,1.2345 =12345 ⏟ significand ×10 ⏟ base −4 ⏞ exponent, the term floating point refers to the fact that a numbers radix point can float, that is, it can be placed anywhere relative to the significant digits of the number. This position is indicated as the exponent component, and thus the floating-point representation can be thought of as a kind of scientific notation. The result of dynamic range is that the numbers that can be represented are not uniformly spaced. Over the years, a variety of floating-point representations have been used in computers, since the 1990s, the most commonly encountered representation is that defined by the IEEE754 Standard. A floating-point unit is a part of a computer system designed to carry out operations on floating point numbers. A number representation specifies some way of encoding a number, usually as a string of digits, there are several mechanisms by which strings of digits can represent numbers.
In common mathematical notation, the string can be of any length. If the radix point is not specified, the string implicitly represents an integer, in fixed-point systems, a position in the string is specified for the radix point. So a fixed-point scheme might be to use a string of 8 decimal digits with the point in the middle. The scaling factor, as a power of ten, is indicated separately at the end of the number, floating-point representation is similar in concept to scientific notation. Logically, a floating-point number consists of, A signed digit string of a length in a given base. This digit string is referred to as the significand, the length of the significand determines the precision to which numbers can be represented. The radix point position is assumed always to be somewhere within the significand—often just after or just before the most significant digit and this article generally follows the convention that the radix point is set just after the most significant digit. A signed integer exponent, which modifies the magnitude of the number, using base-10 as an example, the number 7005152853504700000♠152853.5047, which has ten decimal digits of precision, is represented as the significand 1528535047 together with 5 as the exponent.
In storing such a number, the base need not be stored, since it will be the same for the range of supported numbers. Symbolically, this value is, s b p −1 × b e, where s is the significand, p is the precision, b is the base
A logarithmic scale is a nonlinear scale used when there is a large range of quantities. Common uses include the strength, sound loudness, light intensity. It is based on orders of magnitude, rather than a linear scale. In particular our sense of hearing perceives equal ratios of frequencies as equal differences in pitch, the top left graph is linear in the X and Y axis, and the Y-axis ranges from 0 to 10. A base-10 log scale is used for the Y axis of the left graph. The top right graph uses a scale for just the X axis. A slide rule has logarithmic scales, and nomograms often employ logarithmic scales, the geometric mean of two numbers is midway between the numbers. Before the advent of graphics, logarithmic graph paper was a commonly used scientific tool. If both the vertical and horizontal axes of a plot are scaled logarithmically, the plot is referred to as a log–log plot, if only the ordinate or abscissa is scaled logarithmically, the plot is referred to as a semi-logarithmic plot. Bit Byte Decade John Napier Level Logarithm Logarithmic mean Preferred number Dehaene, Izard, Véronique, Elizabeth, distinct intuitions of the number scale in Western and Amazonian indigene cultures.
American Association for the Advancement of Science, why using logarithmic scale to display share prices
Fax, sometimes called telecopying or telefax, is the telephonic transmission of scanned printed material, normally to a telephone number connected to a printer or other output device. The receiving fax machine interprets the tones and reconstructs the image, early systems used direct conversions of image darkness to audio tone in a continuous or analog manner. Since the 1980s, most machines modulate the audio frequencies using a digital representation of the page which is compressed to quickly transmit areas which are all-white or all-black. Scottish inventor Alexander Bain worked on chemical mechanical fax type devices and he received British patent 9745 on May 27,1843 for his Electric Printing Telegraph. Frederick Bakewell made several improvements on Bains design and demonstrated a telefax machine, the Pantelegraph was invented by the Italian physicist Giovanni Caselli. He introduced the first commercial service between Paris and Lyon in 1865, some 11 years before the invention of the telephone.
In 1880, English inventor Shelford Bidwell constructed the scanning phototelegraph that was the first telefax machine to scan any two-dimensional original, photographs had been sent over the radio using this process. The Western Union Deskfax fax machine, announced in 1948, was a machine that fit comfortably on a desktop. As a designer for the Radio Corporation of America, in 1924, Richard H. Ranger invented the wireless photoradiogram, or transoceanic radio facsimile, the forerunner of today’s fax machines. A photograph of President Calvin Coolidge sent from New York to London on November 29,1924 became the first photo picture reproduced by transoceanic radio facsimile, commercial use of Ranger’s product began two years later. Also in 1924, Herbert E. Ives of AT&T Corporation transmitted and reconstructed the first color facsimile, around 1952 or so, Finch Facsimile, a highly developed machine, was described in detail in a book, it was never manufactured in quantity. By the late 1940s, radiofax receivers were sufficiently miniaturized to be fitted beneath the dashboard of Western Unions Telecar telegram delivery vehicles, in the 1960s, the United States Army transmitted the first photograph via satellite facsimile to Puerto Rico from the Deal Test Site using the Courier satellite.
Radio fax is still in limited use today for transmitting weather charts, in 1964, Xerox Corporation introduced what many consider to be the first commercialized version of the modern fax machine, under the name or Long Distance Xerography. This model was superseded two years with a unit that would set the standard for fax machines for years to come. Up until this point facsimile machines were expensive and hard to operate. In 1966, Xerox released the Magnafax Telecopiers, a smaller and this unit was far easier to operate and could be connected to any standard telephone line. This machine was capable of transmitting a letter-sized document in about six minutes, the first sub-minute, digital fax machine was developed by Dacom, which built on digital data compression technology originally developed at Lockheed for satellite communication. By the late 1970s, many companies around the world, entered the fax market, very shortly after a new wave of more compact and efficient fax machines would hit the market
The decibel is a logarithmic unit used to express the ratio of two values of a physical quantity. One of these values is often a reference value, in which case the decibel is used to express the level of the other value relative to this reference. When used in way, the decibel symbol is often qualified with a suffix that indicates the reference quantity that has been used or some other property of the quantity being measured. For example, dBm indicates a power of one milliwatt. There are two different scales used when expressing a ratio in decibels depending on the nature of the quantities, when expressing power quantities, the number of decibels is ten times the logarithm to base 10 of the ratio of two power quantities. That is, a change in power by a factor of 10 corresponds to a 10 dB change in level, when expressing field quantities, a change in amplitude by a factor of 10 corresponds to a 20 dB change in level. The difference in scales relates to the square law of fields in three-dimensional linear space.
The decibel scales differ so that comparisons can be made between related power and field quantities when they are expressed in decibels. The definition of the decibel is based on the measurement of power in telephony of the early 20th century in the Bell System in the United States. One decibel is one tenth of one bel, named in honor of Alexander Graham Bell, today, the decibel is used for a wide variety of measurements in science and engineering, most prominently in acoustics and control theory. In electronics, the gains of amplifiers, attenuation of signals, the decibel originates from methods used to quantify signal loss in telegraph and telephone circuits. The unit for loss was originally Miles of Standard Cable, the standard telephone cable implied was a cable having uniformly distributed resistance of 88 ohms per loop mile and uniformly distributed shunt capacitance of 0.054 microfarad per mile. 1 TU was defined such that the number of TUs was ten times the logarithm of the ratio of measured power to a reference power level.
The definition was conveniently chosen such that 1 TU approximated 1 MSC, in 1928, the Bell system renamed the TU into the decibel, being one tenth of a newly defined unit for the base-10 logarithm of the power ratio. It was named the bel, in honor of the telecommunications pioneer Alexander Graham Bell, the bel is seldom used, as the decibel was the proposed working unit. However, the decibel is recognized by international bodies such as the International Electrotechnical Commission. The term field quantity is deprecated by ISO 80000-1, which favors root-power, in spite of their widespread use, suffixes are not recognized by the IEC or ISO. The ISO Standard 80000-3,2006 defines the following quantities, the decibel is one-tenth of a bel,1 dB =0.1 B
International Electrotechnical Commission
The IEC manages three global conformity assessment systems that certify whether equipment, system or components conform to its International Standards. The first International Electrical Congress took place in 1881 at the International Exposition of Electricity, at that time the International System of Electrical and Magnetic Units was agreed to. The IEC was instrumental in developing and distributing standards for units of measurement, particularly Gauss, Hertz and it first proposed a system of standards, the Giorgi System, which ultimately became the SI, or Système International d’unités. In 1938, it published a multilingual international vocabulary to unify terminology relating to electrical and this effort continues, and the International Electrotechnical Vocabulary remains an important work in the electrical and electronic industries. The CISPR – in English, the International Special Committee on Radio Interference – is one of the groups founded by the IEC, originally located in London, the commission moved to its current headquarters in Geneva in 1948.
It has regional centres in Asia-Pacific, Latin America and North America, the IEC is the worlds leading international organization in its field, and its standards are adopted as national standards by its members. The work is done by some 10,000 electrical and electronics experts from industry, academia, test labs, IEC standards have numbers in the range 60000–79999 and their titles take a form such as IEC60417, 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 IEC27 became IEC60027. Standards of the 60000 series are preceded by EN to indicate that the IEC standard is adopted by CENELEC as a European standard. The IEC cooperates closely with the International Organization for Standardization and the International Telecommunication Union, Standards developed jointly with ISO such as ISO/IEC26300, ISO/IEC27001, and CASCO ISO/IEC17000 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, other standards developed in cooperation between IEC and ISO are assigned numbers in the 80000 series, such as IEC 82045-1. IEC standards are being adopted by other certifying bodies such as BSI, CSA, UL & ANSI/INCITS, SABS, SAI, SPC/GB, IEC standards adopted by other certifying bodies may have some noted differences from the original IEC standard. The IEC is made up of members, called national committees, national committees are constituted in different ways. Some NCs are public sector only, some are a combination of public and private sector, about 90% of those who prepare IEC standards work in industry
In computing, bit numbering is the convention used to identify the bit positions in a binary number or a container for such a value. The bit number starts with zero and is incremented by one for each subsequent bit position, when the bit numbering starts at zero for the least significant bit the numbering scheme is called LSB0. This bit numbering method has the advantage that for any unsigned number the value of the number can be calculated by using exponentiation with the bit number and a base of 2. The value of a binary integer is therefore ∑ i =0 N −1 b i ⋅2 i where bi denotes the value of the bit with number i. Similarly, when the bit numbering starts at zero for the most significant bit the numbering scheme is called MSB0, when bits are coerced to an array of Boolean, the first element of this array is again the most significant bit. For MSB1 numbering, the value of a binary integer is ∑ i =1 N b i ⋅2 N − i PL/I numbers BIT strings starting with 1 for the leftmost bit. The Fortran BTEST function uses LSB0 numbering, little-endian CPUs usually employ LSB0 bit numbering, however both bit numbering conventions can be seen in big-endian machines.
Some architectures like SPARC and Motorola 68000 use LSB0 bit numbering, while S/390, PowerPC, the recommended style for Request for Comments documents is MSB0 bit numbering. Bit numbering is usually transparent to the software, but some programming languages like Ada or VHDL allow specifying the appropriate bit order for data type representation, Bit Numbers Bit numbering for different CPUs, Motorola 68000 IBM Cell Broadband Processors
MPEG-1 is a standard for lossy compression of video and audio. Today, MPEG-1 has become the most widely compatible lossy audio/video format in the world, perhaps the best-known part of the MPEG-1 standard is the MP3 audio format it introduced. The MPEG-1 standard is published as ISO/IEC11172 – Information technology—Coding of moving pictures, MPEG was formed to address the need for standard video and audio formats, and to build on H.261 to get better quality through the use of more complex encoding methods. Development of the MPEG-1 standard began in May 1988, fourteen video and fourteen audio codec proposals were submitted by individual companies and institutions for evaluation. The codecs were extensively tested for computational complexity and subjective quality and this specific bitrate was chosen for transmission over T-1/E-1 lines and as the approximate data rate of audio CDs. The codecs that excelled in testing were utilized as the basis for the standard and refined further, with additional features.
The reported completion date of the MPEG-1 standard varies greatly, a complete draft standard was produced in September 1990. The draft standard was publicly available for purchase, the standard was finished with the 6 November 1992 meeting. The Berkeley Plateau Multimedia Research Group developed an MPEG-1 decoder in November 1992, due in part to the similarity between the two codecs, the MPEG-2 standard includes full backwards compatibility with MPEG-1 video, so any MPEG-2 decoder can play MPEG-1 videos. This means that MPEG-1 coding efficiency can vary depending on the encoder used. The first three parts of ISO/IEC11172 were published in August 1993, the ISO patent database lists one patent for ISO11172, US4,472,747, which expired in 2003. The near-complete draft of the MPEG-1 standard was publicly available as ISO CD11172 by December 6,1991, a May 2009 discussion on the whatwg mailing list mentioned US5,214,678 patent as possibly covering MPEG audio layer II. Filed in 1990 and published in 1993, this patent is now expired, most popular software for video playback includes MPEG-1 decoding, in addition to any other supported formats.
The popularity of MP3 audio has established a massive installed base of hardware that can play back MPEG-1 Audio, virtually all digital audio devices can play back MPEG-1 Audio. Many millions have been sold to-date, before MPEG-2 became widespread, many digital satellite/cable TV services used MPEG-1 exclusively. The widespread popularity of MPEG-2 with broadcasters means MPEG-1 is playable by most digital cable and satellite set-top boxes, MPEG-1 was used for full-screen video on Green Book CD-i, and on Video CD. The Super Video CD standard, based on VCD, uses MPEG-1 audio exclusively, the DVD-Video format uses MPEG-2 video primarily, but MPEG-1 support is explicitly defined in the standard. The DVD-Video standard originally required MPEG-1 Layer II audio for PAL countries, MPEG-1 Layer II audio is still allowed on DVDs, although newer extensions to the format, like MPEG Multichannel, are rarely supported
Multimedia is content that uses a combination of different content forms such as text, images, animations and interactive content. Multimedia contrasts with media that use only rudimentary computer displays such as text-only or traditional forms of printed or hand-produced material, Multimedia devices are electronic media devices used to store and experience multimedia content. Multimedia is distinguished from mixed media in art, for example. The term rich media is synonymous with interactive multimedia, the term multimedia was coined by singer and artist Bob Goldstein to promote the July 1966 opening of his LightWorks at LOursin show at Southampton, Long Island. Goldstein was perhaps aware of an American artist named Dick Higgins, two years later, in 1968, the term multimedia was re-appropriated to describe the work of a political consultant, David Sawyer, the husband of Iris Sawyer—one of Goldsteins producers at LOursin. In the intervening forty years, the word has taken on different meanings, in the late 1970s, the term referred to presentations consisting of multi-projector slide shows timed to an audio track.
However, by the 1990s multimedia took on its current meaning, in the 1993 first edition of Multimedia, Making It Work, Tay Vaughan declared Multimedia is any combination of text, graphic art, sound and video that is delivered by computer. When you allow the user – the viewer of the project – to control what, when you provide a structure of linked elements through which the user can navigate, interactive multimedia becomes hypermedia. The German language society Gesellschaft für deutsche Sprache recognized the words significance, the institute summed up its rationale by stating has become a central word in the wonderful new media world. In common usage, multimedia refers to an electronically delivered combination of media including video, still images, much of the content on the web today falls within this definition as understood by millions. That era saw a boost in the production of educational multimedia CD-ROMs, the term video, if not used exclusively to describe motion photography, is ambiguous in multimedia terminology.
Video is often used to describe the format, delivery format. Multiple forms of content are often not considered modern forms of presentation such as audio or video. Likewise, single forms of content with single methods of information processing are often called multimedia. Performing arts may be considered multimedia considering that performers and props are multiple forms of content and media. Multimedia presentations may be viewed by person on stage, transmitted, a broadcast may be a live or recorded multimedia presentation. Broadcasts and recordings can be analog or digital electronic media technology. Digital online multimedia may be downloaded or streamed, streaming multimedia may be live or on-demand