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Character Encoding
Character encoding is the process of assigning numbers to graphical characters, especially the written characters of human language, allowing them to be stored, transmitted, and transformed using digital computers. The numerical values that make up a character encoding are known as " code points" and collectively comprise a "code space", a "code page", or a "character map". Early character codes associated with the optical or electrical telegraph could only represent a subset of the characters used in written languages, sometimes restricted to upper case letters, numerals and some punctuation only. The low cost of digital representation of data in modern computer systems allows more elaborate character codes (such as Unicode) which represent most of the characters used in many written languages. Character encoding using internationally accepted standards permits worldwide interchange of text in electronic form. History The history of character codes illustrates the ev ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Code Page
In computing, a code page is a character encoding and as such it is a specific association of a set of printable characters and control characters with unique numbers. Typically each number represents the binary value in a single byte. (In some contexts these terms are used more precisely; see .) The term "code page" originated from IBM's EBCDIC-based mainframe systems, but Microsoft, SAP, and Oracle Corporation are among the vendors that use this term. The majority of vendors identify their own character sets by a name. In the case when there is a plethora of character sets (like in IBM), identifying character sets through a number is a convenient way to distinguish them. Originally, the code page numbers referred to the ''page'' numbers in the IBM standard character set manual, a condition which has not held for a long time. Vendors that use a code page system allocate their own code page number to a character encoding, even if it is better known by another name; for example ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Unicode
Unicode, formally The Unicode Standard,The formal version reference is is an information technology standard for the consistent encoding, representation, and handling of text expressed in most of the world's writing systems. The standard, which is maintained by the Unicode Consortium, defines as of the current version (15.0) 149,186 characters covering 161 modern and historic scripts, as well as symbols, emoji (including in colors), and non-visual control and formatting codes. Unicode's success at unifying character sets has led to its widespread and predominant use in the internationalization and localization of computer software. The standard has been implemented in many recent technologies, including modern operating systems, XML, and most modern programming languages. The Unicode character repertoire is synchronized with ISO/IEC 10646, each being code-for-code identical with the other. ''The Unicode Standard'', however, includes more than just the base code. Alon ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Émile Baudot
Jean-Maurice-Émile Baudot (; 11 September 1845 – 28 March 1903), French telegraph engineer and inventor of the first means of digital communication Baudot code, was one of the pioneers of telecommunications. He invented a multiplexed printing telegraph system that used his code and allowed multiple transmissions over a single line. The baud unit was named after him. Early life Baudot was born in Magneux, Haute-Marne, France, the son of farmer Pierre Emile Baudot, who later became the mayor of Magneux. His only formal education was at his local primary school, after which he carried out agricultural work on his father's farm before joining the French Post & Telegraph Administration as an apprentice operator in 1869. The telegraph service trained him in the Morse telegraph and also sent him on a four-month course of instruction on the Hughes printing telegraph system, which was later to inspire his own system. After serving briefly during the Franco-Prussian War, he return ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
ASCII
ASCII ( ), abbreviated from American Standard Code for Information Interchange, is a character encoding standard for electronic communication. ASCII codes represent text in computers, telecommunications equipment, and other devices. Because of technical limitations of computer systems at the time it was invented, ASCII has just 128 code points, of which only 95 are , which severely limited its scope. All modern computer systems instead use Unicode, which has millions of code points, but the first 128 of these are the same as the ASCII set. The Internet Assigned Numbers Authority (IANA) prefers the name US-ASCII for this character encoding. ASCII is one of the IEEE milestones. Overview ASCII was developed from telegraph code. Its first commercial use was as a seven- bit teleprinter code promoted by Bell data services. Work on the ASCII standard began in May 1961, with the first meeting of the American Standards Association's (ASA) (now the American National Standards ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Baudot Code
The Baudot code is an early character encoding for telegraphy invented by Émile Baudot in the 1870s. It was the predecessor to the International Telegraph Alphabet No. 2 (ITA2), the most common teleprinter code in use until the advent of ASCII. Each character in the alphabet is represented by a series of five bits, sent over a communication channel such as a telegraph wire or a radio signal by asynchronous serial communication. The symbol rate measurement is known as baud, and is derived from the same name. History Baudot code (ITA1) In the below table, Columns I, II, III, IV, and V show the code; the Let. and Fig. columns show the letters and numbers for the Continental and UK versions; and the sort keys present the table in the order: alphabetical, Gray and UK Baudot developed his first multiplexed telegraph in 1872 [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Non-directional Beacon
A non-directional beacon (NDB) or non-directional radio beacon is a radio beacon which does not include directional information. Radio beacons are radio transmitters at a known location, used as an aviation or marine navigational aid. NDB are in contrast to directional radio beacons and other navigational aids, such as low-frequency radio range, VHF omnidirectional range (VOR) and tactical air navigation system (TACAN). NDB signals follow the curvature of the Earth, so they can be received at much greater distances at lower altitudes, a major advantage over VOR. However, NDB signals are also affected more by atmospheric conditions, mountainous terrain, coastal refraction and electrical storms, particularly at long range. The system, developed by United States Air Force (USAF) Captain Albert Francis Hegenberger, was used to fly the world's first instrument approach on May 9, 1932. Types of NDBs NDBs used for aviation are standardised by International Civil Aviation Organ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Amateur Radio
Amateur radio, also known as ham radio, is the use of the radio frequency spectrum for purposes of non-commercial exchange of messages, wireless experimentation, self-training, private recreation, radiosport, contesting, and emergency communications. The term "amateur" is used to specify "a duly authorised person interested in radioelectric practice with a purely personal aim and without pecuniary interest;" (either direct monetary or other similar reward) and to differentiate it from commercial broadcasting, public safety (such as police and fire), or professional two-way radio services (such as maritime, aviation, taxis, etc.). The amateur radio service (''amateur service'' and '' amateur-satellite service'') is established by the International Telecommunication Union (ITU) through the Radio Regulations. National governments regulate technical and operational characteristics of transmissions and issue individual station licenses with a unique identifying call sign, which ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Telegraph Key
A telegraph key is a specialized electrical switch used by a trained operator to transmit text messages in Morse code in a telegraphy system. Keys are used in all forms of electrical telegraph systems, including landline (also called wire) telegraphy and radio (also called wireless) telegraphy. An operator uses the telegraph key to send electrical pulses (or in the case of modern CW, unmodulated radio waves) of two different lengths: short pulses, called ''dots'' or ''dits'', and longer pulses, called ''dashes'' or ''dahs''. These pulses encode the letters and other characters that spell out the message. Types Since its original inception, the telegraph key's design has developed such that there are now multiple types of keys. Straight keys A ''straight key'' is the common telegraph key as seen in various movies. It is a simple bar with a knob on top and an electrical contact underneath. When the bar is pressed down against spring tension, it makes a closed electric ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Morse Code
Morse code is a method used in telecommunication to encode text characters as standardized sequences of two different signal durations, called ''dots'' and ''dashes'', or ''dits'' and ''dahs''. Morse code is named after Samuel Morse, one of the inventors of the telegraph. International Morse code encodes the 26 basic Latin letters through , one accented Latin letter (), the Arabic numerals, and a small set of punctuation and procedural signals ( prosigns). There is no distinction between upper and lower case letters. Each Morse code symbol is formed by a sequence of ''dits'' and ''dahs''. The ''dit'' duration is the basic unit of time measurement in Morse code transmission. The duration of a ''dah'' is three times the duration of a ''dit''. Each ''dit'' or ''dah'' within an encoded character is followed by a period of signal absence, called a ''space'', equal to the ''dit'' duration. The letters of a word are separated by a space of duration equal to three ''dits' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hans Schjellerup
Hans Carl Frederik Christian Schjellerup (8 February 1827 – 13 November 1887) was a Danish astronomer. He was born at Odense, the son of a jeweller. Initially he was apprenticed as a watch maker, but in 1848 he passed the entrance exam for the Polytechnic School of Copenhagen. He graduated by passing an examination in applied mathematics and mechanics. In 1851 he became an observer at the University Observatory in Copenhagen. He soon became an instructor at the Polytechnic School, then in 1854 a Professor of Mathematics at the Denmark Naval Academy. In 1866, after the new observatory had been completed, Schjellerup assembled a catalog of red stars. He also began a study of Arabic, Chinese and other oriental languages, and used his knowledge to study old astronomic records, including those of Abd-al-Rahman al-Sûfi (whose ''Book of Fixed Stars'' he translated into French in 1874) and Chinese records of eclipses. In 1869, he drafted a proposal for a Chinese telegraph dictionar ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
