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Slave Clock
In telecommunication and horology, a slave clock is a clock that depends on another clock, the master clock. Modern clocks are synchronized through the Internet or by radio time signals, to Coordinated Universal Time. UTC is based on a network of atomic clocks in many countries. For scientific purposes, precision clocks can be synchronized to within nanoseconds by dedicated satellite channels. Slave clock synchronization is usually achieved by phase-locking the slave clock signal to a signal received from the master clock. To adjust for the transit time of the signal from the master clock to the slave clock, the phase of the slave clocks are adjusted so that both clocks are in phase. Thus, the time markers of both clocks, at the output of the clocks, occur simultaneously. The predecessors of atomic clocks, computer clocks, digital clocks, these electric clocks were synchronized by an electrical pulse, wired to their master clock in the same facility. Thus the terms "master" a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Master Clock System
Master or masters may refer to: Ranks or titles *Ascended master, a term used in the Theosophical religious tradition to refer to spiritually enlightened beings who in past incarnations were ordinary humans *Grandmaster (chess), National Master, International Master, FIDE Master, Candidate Master, all ranks of chess player *Grandmaster (martial arts) or Master, an honorary title *Grand master (order), a title denoting the head of an order or knighthood *Grand Master (Freemasonry), the head of a Grand Lodge and the highest rank of a Masonic organization *Maestro, an orchestral conductor, or the master within some other musical discipline *Master, a Names and titles of Jesus in the New Testament#Master, title of Jesus in the New Testament *Master or shipmaster, the sea captain of a merchant vessel *Master (college), head of a college *Master (form of address), an English honorific for boys and young men *Master (judiciary), a judicial official in the courts of common law jurisdictio ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Time
Time is the continued sequence of existence and events that occurs in an apparently irreversible succession from the past, through the present, into the future. It is a component quantity of various measurements used to sequence events, to compare the duration of events or the intervals between them, and to quantify rates of change of quantities in material reality or in the conscious experience. Time is often referred to as a fourth dimension, along with three spatial dimensions. Time has long been an important subject of study in religion, philosophy, and science, but defining it in a manner applicable to all fields without circularity has consistently eluded scholars. Nevertheless, diverse fields such as business, industry, sports, the sciences, and the performing arts all incorporate some notion of time into their respective measuring systems. 108 pages. Time in physics is operationally defined as "what a clock reads". The physical nature of time is addre ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Telecommunications Equipment
Telecommunications equipment (also telecoms equipment or communications equipment) are hardware which are used for the purposes of telecommunications. Since the 1990s the boundary between telecoms equipment and IT hardware has become blurred as a result of the growth of the internet and its increasing role in the transfer of telecoms data. Types Telecommunications equipment can be broadly broken down into the following categories: *Public switching equipment **Analogue switches **Digital switches ***Voice over IP switches ***Virtual reality (VR) *Transmission equipment **Transmission lines ***Optical fiber ***Local loops **Base transceiver stations **Free-space optical communication ***Laser communication in space **Multiplexers **Communications satellites *Customer premises equipment (CPE) ** Customer office terminal **Private switches **Local area networks (LANs) **Modems **Mobile phones ** Landline telephones **Answering machines **Teleprinters **Fax machines **Pagers ** Router ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
21st Century
The 21st (twenty-first) century is the current century in the ''Anno Domini'' era or Common Era, under the Gregorian calendar. It began on 1 January 2001 ( MMI) and will end on 31 December 2100 ( MMC). Marking the beginning of the 21st century was the rise of a global economy and Third World consumerism, deepening global concern over terrorism after 11 September 2001, terrorist attacks and increased private enterprise. The NATO interventions in Afghanistan and Iraq of the early 2000s and overthrowing several regimes during the Arab Spring of the early 2010s led to mixed outcomes in the Arab world, resulting in several civil wars and political instability. The United States has remained the global superpower, while China is now considered an emerging superpower. In 2017, 49.3% of the world's population lived in "some form of democracy", though only 4.5% lived in "full democracies". The United Nations estimates that by 2050 two thirds of the world's population will be urbani ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Principal (education)
A head master, head instructor, bureaucrat, headmistress, head, chancellor, principal or school director (sometimes another title is used) is the staff member of a school with the greatest responsibility for the management of the school. In some English-speaking countries, the title for this role is '' principal.'' Description School principals are stewards of learning and managing supervisors of their schools. They aim to provide vision and leadership to all stakeholders in the school and create a safe and peaceful environment to achieve the mission of learning and educating at the highest level. They guide the day to day school business and oversee all activities conducted by the school. They bear the responsibility of all decision making and are accountable for their efforts to elevate the school to the best level of learning achievements for the students, best teaching skills for the teachers and best work environment for support staff. Role While some head teachers still ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Elementary Schools
A primary school (in Ireland, the United Kingdom, Australia, Trinidad and Tobago, Jamaica, and South Africa), junior school (in Australia), elementary school or grade school (in North America and the Philippines) is a school for primary education of children who are four to eleven years of age. Primary schooling follows pre-school and precedes secondary schooling. The International Standard Classification of Education considers primary education as a single phase where programmes are typically designed to provide fundamental skills in reading, writing, and mathematics and to establish a solid foundation for learning. This is International Standard Classification of Education#Level 1, ISCED Level 1: Primary education or first stage of basic education.Annex III in the ISCED 2011 English.pdf Na ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
School Bell
The ringing of a school bell announces important times to a school's students and staff, such as marking the beginnings and ends of the school day, class period, and breaks. In some schools it may take the form of a physical bell, usually electrically operated. In other schools it may be a tone, siren, electronic bell sound, a series of chimes, or music played over a PA system. In East Asian nations such as China, North Korea and South Korea, the Westminster Chimes pattern is commonly played as the bell. Schools for the hearing impaired use alternative signaling methods, for example sign language from the teacher and lights that illuminate when the public address/bell is sounding. Criticism In October 2010, Mackie Academy in Stonehaven, Kincardineshire, Scotland, took the move to turn off their school bell system, following criticism that the school bells agitated pupils. According to the headteacher, the corridors became much quieter after the system was introduced. I ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Electric Clocks
An electric clock is a clock that is powered by electricity, as opposed to a mechanical clock which is powered by a hanging weight or a mainspring. The term is often applied to the electrically powered mechanical clocks that were used before quartz clocks were introduced in the 1980s. The first experimental electric clocks were constructed around the 1840s, but they were not widely manufactured until mains electric power became available in the 1890s. In the 1930s, the synchronous electric clock replaced mechanical clocks as the most widely used type of clock. Types Electric clocks can operate by several different types of mechanism: *''Electromechanical clocks'' have a traditional mechanical movement, which keeps time with an oscillating pendulum or balance wheel powered through a gear train by a mainspring, but use electricity to rewind the mainspring with an electric motor or electromagnet. This mechanism is found mostly in antique clocks. *''Electric remontoire clocks'' hav ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Digital Clock
A digital clock is a type of clock that displays the time digitally (i.e. in numerals or other symbols), as opposed to an analogue clock. Digital clocks are often associated with electronic drives, but the "digital" description refers only to the display, not to the drive mechanism. (Both analogue and digital clocks can be driven either mechanically or electronically, but "clockwork" mechanisms with digital displays are rare). History The first digital pocket watch was the invention of Austrian engineer Josef Pallweber who created his "jump-hour" mechanism in 1883. Instead of a conventional dial, the jump-hour featured two windows in an enamel dial, through which the hours and minutes are visible on rotating discs. The second hand remained conventional. By 1885 Pallweber mechanism was already on the market in pocket watches by Cortébert and IWC; arguably contributing to the subsequent rise and commercial success of IWC. The principles of Pallweber jump-hour movement had a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Computer Clock
In electronics and especially synchronous digital circuits, a clock signal (historically also known as ''logic beat'') oscillates between a high and a low state and is used like a metronome to coordinate actions of digital circuits. A clock signal is produced by a clock generator. Although more complex arrangements are used, the most common clock signal is in the form of a square wave with a 50% duty cycle, usually with a fixed, constant frequency. Circuits using the clock signal for synchronization may become active at either the rising edge, falling edge, or, in the case of double data rate, both in the rising and in the falling edges of the clock cycle. Digital circuits Most integrated circuits (ICs) of sufficient complexity use a clock signal in order to synchronize different parts of the circuit, cycling at a rate slower than the worst-case internal propagation delays. In some cases, more than one clock cycle is required to perform a predictable action. As ICs become more ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Clock Signal
In electronics and especially synchronous digital circuits, a clock signal (historically also known as ''logic beat'') oscillates between a high and a low state and is used like a metronome to coordinate actions of digital circuits. A clock signal is produced by a clock generator. Although more complex arrangements are used, the most common clock signal is in the form of a square wave with a 50% duty cycle, usually with a fixed, constant frequency. Circuits using the clock signal for synchronization may become active at either the rising edge, falling edge, or, in the case of double data rate, both in the rising and in the falling edges of the clock cycle. Digital circuits Most integrated circuits (ICs) of sufficient complexity use a clock signal in order to synchronize different parts of the circuit, cycling at a rate slower than the worst-case internal propagation delays. In some cases, more than one clock cycle is required to perform a predictable action. As ICs become mo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Telecommunication
Telecommunication is the transmission of information by various types of technologies over wire, radio, optical, or other electromagnetic systems. It has its origin in the desire of humans for communication over a distance greater than that feasible with the human voice, but with a similar scale of expediency; thus, slow systems (such as postal mail) are excluded from the field. The transmission media in telecommunication have evolved through numerous stages of technology, from beacons and other visual signals (such as smoke signals, semaphore telegraphs, signal flags, and optical heliographs), to electrical cable and electromagnetic radiation, including light. Such transmission paths are often divided into communication channels, which afford the advantages of multiplexing multiple concurrent communication sessions. ''Telecommunication'' is often used in its plural form. Other examples of pre-modern long-distance communication included audio messages, such as coded drumb ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
