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PCH 11 Coaxial-Cable(同軸電纜)
learning objectives/學習目標
Identify types of network cables and connectors.
識別網絡電纜和連接器的類型。
Coaxial cable is a much older media technology. Coaxial cable, also known as coax for short, is composed of two conductors. The inner conductor, which is known as the insulated conductor (center wire), is the copper wire over which data is passed. The outer conductor is the braided metal shield and aids in protecting the inner wire from physical injury and the effects of EMI. Much like the shielding we saw in shielded twisted pair, the outer shield helps keep electromagnetic interference out of the data’s path. Between the inner conductor and the outer shield, we find an insulated core that prevents any data transfer between the inner core and outer shield. The outside of the cable is made of a flexible plastic jacket, much like the twisted pair cabling. Coaxial cabling was included in the first Ethernet standard as 10Base5 (thicknet) and continued to be used throughout updates as 10Base2 (thinnet) as well as being most commonly used in bus and ring networks. UTP cabling however, is easier to work with in a star topology and is significantly less expensive.
同軸電纜是一種較老的媒體技術。同軸電纜（也簡稱為同軸電纜）由兩個導體組成。內部導體（稱為絕緣導體（中心線）)是其上傳數據的銅線。外導體是編織的金屬屏蔽層，有助於保護內線免受傷害和電磁干擾的影響。就像我們在屏蔽雙絞線中看到的屏蔽層一樣，外部屏蔽有助於將電磁干擾排除在數據路徑之外。在內部導體和外部屏蔽層之間，我們找到了一個絕緣芯，可防止在內芯和外部屏蔽層之間進行任何數據傳輸。電纜的外部由柔軟的塑膠護套製成，非常類似於雙絞線電纜。同軸電纜已包含在第一個以太網標準中，稱為10Base5（Thicknet），並在整個更新中繼續用作10Base2（Thinnet），並且在總線和環形網絡中最常用。但是，非屏蔽雙絞線電纜更容易在星形網中使用，且價格便宜得多。
2.Coaxial Cable Types(同軸電纜之類型)
There are three dominant coaxial cable types. The RG-6 is commonly used by cable TV companies to connect individual homes to the TV network. These cables are thick and usually used for outside connections to withstand the effects of the weather. The RG-58 is a type of coaxial cable that was heavily used in early 10Base2 (thinnet) networks, such as bus and ring topologies. Finally, the RG-59 is the traditional coaxial cable used to carry composite video between two nearby devices, such as your TV and the cable box. If you are a cable Internet user, this is also used to carry the WAN connection from your wall jack to your cable modem.
共有三種主要的同軸電纜類型。有線電視公司通常使用RG-6將單個房屋連接到電視網絡。這些電纜很粗，通常用於外部連接並可以承受天氣的影響。 RG-58是一種同軸電纜，在諸如總線和環形拓撲之類的早期10Base2（瘦網）網絡中大量使用。最後，RG-59是傳統的同軸電纜，用於在兩個附近的設備（例如電視和電纜盒）之間傳送複合影片。如果您是有線網路用戶，這也可用於將廣域網路連接從牆壁插孔連接到電纜調製解調器。
3.Coaxial Cable Connectors(同軸電纜連接器)
While there were three types of cables, there are only two types of common connectors used with coaxial cable. The first is called BNC, from the name Bayonet Neill-Concelman. Sometimes people also call this the British Naval connector, because the BNC was heavily used by the British in their shipboard radio systems. This connector was commonly used in early Ethernet networks and it has a “push and twist” type of connector to secure the cable to the network device.
雖然有三種類型的電纜，但同軸電纜僅使用兩種類型的普通連接器。第一個稱為BNC，名稱為刺刀Neill-Concelman。有時人們也將其稱為英國海軍連接器，因為英國人在其艦載無線電系統中大量使用了BNC。該連接器通常用於早期的以太網網絡，並且具有“推壓式”連接器，用於將電纜固定至網絡設備。
Coaxial jack.(同軸插孔)
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