算機網絡畢業論文中英文資料外文翻譯文獻(編輯修改稿)

　

【文章內容簡介】 s the most widely used medium for telemunication. Twistedpair cabling consist of copper wires that are twisted into pairs. Ordinary telephone wires consist of two insulated copper wires twisted into pairs. Computer working cabling consist of 4 pairs of copper cabling that can be utilized for both voice and data transmission. The use of two wires twisted together helps to reduce crosstalk and electromagic induction. The transmission speed ranges from 2 中英文資料 million bits per second to 100 million bits per second. Twisted pair cabling es in two forms which are Unshielded Twisted Pair (UTP) and Shielded twistedpair (STP) which are rated in categories which are manufactured in different increments for various scenarios. Coaxial cable is widely used for cable television systems, office buildings, and other worksites for local area works. The cables consist of copper or aluminum wire wrapped with insulating layer typically of a flexible material with a high dielectric constant, all of which are surrounded by a conductive layer. The layers of insulation help minimize interference and distortion. Transmission speed range from 200 million to more than 500 million bits per second. Optical fiber cable consists of one or more filaments of glass fiber wrapped in protective layers. It transmits light which can travel over extended distances. Fiberoptic cables are not affected by electromagic radiation. Transmission speed may reach trillions of bits per second. The transmission speed of fiber optics is hundreds of times faster than for coaxial cables and thousands of times faster than a twistedpair wire.[citation needed] Wireless technologies Terrestrial microwave – Terrestrial microwaves use Earthbased transmitter and receiver. The equipment looks similar to satellite dishes. Terrestrial microwaves use lowgigahertz range, which limits all munications to lineofsight. Path between relay stations spaced approx, 30 miles apart. Microwave antennas are usually placed on top of buildings, towers, hills, and mountain peaks. Communications satellites – The satellites use microwave radio as their telemunications medium which are not deflected by the Earth39。s atmosphere. The satellites are stationed in space, typically 22,000 miles (for geosynchronous satellites) above the equator. These Earthorbiting systems are capable of receiving and relaying voice, data, and TV signals. Cellular and PCS systems – Use several radio munications technologies. The systems are divided to different geographic areas. Each area has a lowpower transmitter or radio relay antenna device to relay calls from one area to the next area. 中英文資料 Wireless LANs – Wireless local area work use a highfrequency radio technology similar to digital cellular and a lowfrequency radio technology. Wireless LANs use spread spectrum technology to enable munication between multiple devices in a limited area. An example of openstandards wireless radiowave technology is IEEE. Infrared munication , which can transmit signals between devices within small distances not more than 10 meters peer to peer or ( face to face ) without any body in the line of transmitting. Scale Networks are often classified as local area work (LAN), wide area work (WAN), metropolitan area work (MAN), personal area work (PAN), virtual private work (VPN), campus area work (CAN), storage area work (SAN), and others, depending on their scale, scope and purpose, ., controller area work (CAN) usage, trust level, and access right often differ between these types of works. LANs tend to be designed for internal use by an anization39。s internal systems and employees in individual physical locations, such as a building, while WANs may connect physically separate parts of an anization and may include connections to third parties. Functional relationship (work architecture) Computer works may be classified according to the functional relationships which exist among the elements of the work, ., active working, client–server, Wireless ad hoc work and peertopeer (workgroup) architecture. Network topology Main article: Network topology Computer works may be classified according to the work topology upon which the work is based, such as bus work, star work, ring work, mesh work. Network topology is the coordination by which devices in the work are arranged in their logical relations to one another, independent of physical arrangement. Even if worked puters are physically placed in a linear arrangement and are connected to a hub, the work has a star topology, rather than a bus topology. In this regard the visual and operational characteristics of a work are distinct. Networks may be 中英文資料 classified based on the method of data used to convey the data, these incl