Field (mathematics)In mathematics, a field is a set on which addition, subtraction, multiplication, and division are defined and behave as the corresponding operations on rational and real numbers do. A field is thus a fundamental algebraic structure which is widely used in algebra, number theory, and many other areas of mathematics. The best known fields are the field of rational numbers, the field of real numbers and the field of complex numbers.
Echo suppression and cancellationEcho suppression and echo cancellation are methods used in telephony to improve voice quality by preventing echo from being created or removing it after it is already present. In addition to improving subjective audio quality, echo suppression increases the capacity achieved through silence suppression by preventing echo from traveling across a telecommunications network. Echo suppressors were developed in the 1950s in response to the first use of satellites for telecommunications.
Equalization (communications)In telecommunication, equalization is the reversal of distortion incurred by a signal transmitted through a channel. Equalizers are used to render the frequency response—for instance of a telephone line—flat from end-to-end. When a channel has been equalized the frequency domain attributes of the signal at the input are faithfully reproduced at the output. Telephones, DSL lines and television cables use equalizers to prepare data signals for transmission.
Direct-sequence spread spectrumIn telecommunications, direct-sequence spread spectrum (DSSS) is a spread-spectrum modulation technique primarily used to reduce overall signal interference. The direct-sequence modulation makes the transmitted signal wider in bandwidth than the information bandwidth. After the despreading or removal of the direct-sequence modulation in the receiver, the information bandwidth is restored, while the unintentional and intentional interference is substantially reduced.
Filename extensionA filename extension, file name extension or file extension is a suffix to the of a (for example, .txt, .docx, .md). The extension indicates a characteristic of the file contents or its intended use. A filename extension is typically delimited from the rest of the filename with a full stop (period), but in some systems it is separated with spaces. Other extension formats include dashes and/or underscores on early versions of Linux and some versions of IBM AIX.
Far EastIn European terminology, the Far East is the geographical region that encompasses the easternmost portion of the Asian continent, including East, North and Southeast Asia. South Asia is sometimes also included in the definition of the term. The term first came into use in European geopolitical discourse in the 15th century, particularly the British, denoting the Far East as the "farthest" of the three "Easts", beyond the Near East and the Middle East. Likewise, during the Qing dynasty of the 19th and early 20th centuries, the term "Tàixī (泰西)" – i.
Special operationsSpecial operations or spec ops are military activities conducted, according to NATO, by "specially designated, organized, selected, trained, and equipped forces using unconventional techniques and modes of employment." Special operations may include reconnaissance, unconventional warfare, and counterterrorism, and are typically conducted by small groups of highly trained personnel, emphasizing sufficiency, stealth, speed, and tactical coordination, commonly known as special forces.
Straightedge and compass constructionIn geometry, straightedge-and-compass construction – also known as ruler-and-compass construction, Euclidean construction, or classical construction – is the construction of lengths, angles, and other geometric figures using only an idealized ruler and a pair of compasses. The idealized ruler, known as a straightedge, is assumed to be infinite in length, have only one edge, and no markings on it. The compass is assumed to have no maximum or minimum radius, and is assumed to "collapse" when lifted from the page, so may not be directly used to transfer distances.
Russian Far EastThe Russian Far East (Дальний Восток России) is a region in Northeast Asia. It is the easternmost part of Russia and the Asian continent; and is administered as a part of the Far Eastern Federal District, which is located between Lake Baikal in eastern Siberia and the Pacific Ocean. The area's largest city is Khabarovsk, followed by Vladivostok. The region shares land borders with the countries of Mongolia, China, and North Korea to its south, as well as maritime boundaries with Japan to its southeast, and with the United States along the Bering Strait to its northeast.
Special Air ServiceThe Special Air Service (SAS) is a special forces unit of the British Army. It was founded as a regiment in 1941 by David Stirling and in 1950, it was reconstituted as a corps. The unit specialises in a number of roles including counter-terrorism, hostage rescue, direct action and covert reconnaissance. Much of the information about the SAS is highly classified, and the unit is not commented on by either the British government or the Ministry of Defence due to the secrecy and sensitivity of its operations.
