【正文】 msWhich technologies will meet speed and datatransmission requirements in the future?To discuss the future of structured cabling systems, we should spend a moment looking at the past and present practices. Before early 1984, munications wiring systems, as they were then called, were not topics of much discussion. Datatransport speeds were paratively slow, transmission bandwidth requirements were minimal, and others provided the design and installation of the cabling system. The telephone panies took care of the installation and maintenance of the telephone service. When data services became distributed, the cabling system was vendorspecific, and the installation and maintenance of the cable plant was provided by the equipment vendors, or specialized independent contractors.In January 1984, the courts in the . made several important rulings that changed the way telemunications was provided and distributed. Outside of traditional suppliers of cabling systems, not much was understood about the cabling requirements for munications transport. The proliferation of media and connector interfaces, a lack of standard transmission specifications, and the introduction of cabling schemes by vendors added to the user39。s Bill Gates is quoted as saying, We will have infinite bandwidth in a decade39。和其他區(qū)各種布線系統(tǒng)相比，數(shù)據(jù)傳輸速率低，對(duì)傳輸帶寬的要求是很小的。一些組織也對(duì)綜合布線的各個(gè)方面發(fā)布了一系列的標(biāo)準(zhǔn)和規(guī)范。仍繼續(xù)使用低帶寬的領(lǐng)域如，樓宇自控系統(tǒng)，報(bào)警系統(tǒng)及安全防范系統(tǒng)。勞倫斯伯克利實(shí)驗(yàn)室預(yù)測(cè)到2020傳輸速度將達(dá)到40Gb/s。但可以相信這些障礙，無論是技術(shù)方面的還是政治方面的，都會(huì)得到解決。盡管屏蔽雙絞線是一個(gè)良好的傳輸媒介，但原材料和安裝費(fèi)用較高，限制了其使用。今天，該技術(shù)已支持多達(dá)40個(gè)不同的波長(zhǎng)。如今的市場(chǎng)只接受有書面認(rèn)可的產(chǎn)品，而且低成本的塑料光纖也不會(huì)被市場(chǎng)接受。有了無線技術(shù)，他們不再關(guān)注電纜能不能達(dá)到地方，也不再關(guān)注電纜的類型。成本的考慮不能只考慮材料成本而做出購(gòu)買決定，還應(yīng)考慮到到系統(tǒng)的需求。它可能會(huì)是一個(gè)更大的市場(chǎng)份額，尤其是在住宅環(huán)境中。而且，即使在千兆以太網(wǎng)協(xié)議來到我們之前一段時(shí)間里，用5類和6類將支持它就好了，我們知道在未來5至10年，10千兆位以太網(wǎng)將需要一個(gè)完全光纖基礎(chǔ)設(shè)施。在相同的帶寬中使用雙比特率的信號(hào)將會(huì)大大增加電子產(chǎn)品的成本，因?yàn)樗鼤?huì)采取更復(fù)雜的設(shè)備去解密傳輸信號(hào)。雖然無線網(wǎng)絡(luò)有一個(gè)由電氣和電子工程師協(xié)會(huì)提出的IEEE ，但是該標(biāo)準(zhǔn)并沒有在所有的無限局域網(wǎng)廠商中實(shí)現(xiàn)。同軸電纜同軸電纜被規(guī)范應(yīng)用于有線電視系統(tǒng)的基帶和寬帶傳輸。這一技術(shù)發(fā)展最好的結(jié)果是，一個(gè)新波長(zhǎng)可以耦合到光線路的同一根光纖中進(jìn)行傳輸。但相對(duì)于非屏蔽雙絞線，屏蔽雙絞線的花費(fèi)較高是它的一個(gè)主要缺點(diǎn)。非屏蔽雙絞線的持續(xù)有效性能否跟隨信息傳輸速率一起提高仍然是一個(gè)問題。毫無疑問，光纖和屏蔽雙絞線比非屏蔽雙絞線傳輸?shù)男畔⒘扛?。?shù)據(jù)包，其中包括語(yǔ)音數(shù)據(jù)包，將增加帶寬的要求。用于商業(yè)界的絕大部分的過去和現(xiàn)在的數(shù)字通信系統(tǒng)，都已運(yùn)用非屏蔽雙絞線。當(dāng)數(shù)據(jù)服務(wù)成為分散式的，有負(fù)責(zé)布線系統(tǒng)的廠商，有負(fù)責(zé)安裝及維修電纜的設(shè)備廠商，或?qū)ｉT的獨(dú)立承包商。s applications. But will UTP and other media systems provide the bandwidth for future applications? Will they provide economical solutions? Let39。w 畢業(yè)設(shè)計(jì)外文文獻(xiàn)及譯文文獻(xiàn)、資料題目:The future of structure cabling systems文獻(xiàn)、資料來源: Cabling Installation amp。s time. Lawrence Berkeley Laboratory (Berkeley, CA) has projected its throughput needs for 2020 to be 40 Gb/s. What will be its media of choice: UTP, coaxial, shielded twistedpair, optical fiber, or wireless technology?The two major properties required for any cabling system to be the system of choice are its performance and its relative economics (which include ease of installation). Undoubtedly, fiber and shielded twistedpair (STP) systems are quite robust and provide greater signal headroom than UTP. However, they lag far behind UTP in customer acceptance for today39。電話公司只負(fù)責(zé)電話的安裝和維修服務(wù)。這些標(biāo)準(zhǔn)有助于發(fā)展高速傳輸系統(tǒng)。語(yǔ)音信息可以從中央辦公室傳遞到智能外設(shè)，但并不需要增加帶寬。要達(dá)到如此高的速度應(yīng)選擇哪種傳輸介質(zhì)呢？是雙絞線，電纜，屏蔽雙絞線，光纖還是無線技術(shù)？系統(tǒng)性能和經(jīng)濟(jì)性是挑選布線系統(tǒng)的兩項(xiàng)重要依據(jù)。人們普遍認(rèn)為，非屏蔽雙絞線的傳輸速率還尚未達(dá)到極限。毫無疑問，屏蔽雙絞線還尚未達(dá)到傳輸極限。在不久的將來，可達(dá)到128通道。如果要讓一個(gè)標(biāo)準(zhǔn)化組織認(rèn)可塑料光纖，它應(yīng)該具有比玻璃光纖成本低且更加穩(wěn)定的性能。但是無線網(wǎng)絡(luò)所有的魔法都有缺點(diǎn)。例如，5類電纜的特點(diǎn)是在頻率為100MHz，而6類的特點(diǎn)是21/2倍帶寬。用戶應(yīng)該有興趣將信息傳輸系統(tǒng)作為一種提高的企業(yè)生產(chǎn)力工具，而不是一個(gè)技術(shù)與其他技