電子信息工程外文翻譯--綜合布線的未來適用于畢業(yè)論文外文翻譯中英文對照-免費閱讀
【正文】 看來，最終的解決辦法可能是將多種光纖組合使用。在很長的一段時間內(nèi)屏蔽雙絞線將在高電磁干擾的環(huán)境中繼續(xù)使用。在一個開放的辦公方案中，傳播的無線電波可能受限的距離為200英尺到500英尺。無線技術(shù)很多人指出，在綜合布線系統(tǒng)中無線技術(shù)將會逐步取代傳統(tǒng)的線纜。塑料光纖縱觀歷史，塑料光纖已被應(yīng)用到低速，短距離的傳輸系統(tǒng)當中。光纖波分復(fù)用光纖波分復(fù)用是一種新興的技術(shù)。屏蔽雙絞線屏蔽雙絞線的特點是其頻率目前在300MHz。非屏蔽雙絞線目前，非屏蔽雙絞線的傳輸速度已達到250MHz。如果未來是可以預(yù)測的，我們將看到信息的傳遞速度每十年至少提高一個數(shù)量級。1991年雙絞線的最高帶寬是16MHz，現(xiàn)在面臨的是帶寬超過250MHz及以上的要求。多媒體擴展連接接口缺乏標準傳輸規(guī)范，廠商介紹的各種布線方案給使用者造成了許多混亂。s bandwidth limitations have not yet been reached, but as is the case with UTP, economics could be the major stumbling block to its adaptation. The installation of STP requires highly trained installers. North American industry experts doubt that end users or installation contractors will be quick to embrace STP. Fiberoptic WDM Wave division multiplexing (WDM) is a new technology that expands the datacarrying capacity of optical fiber rather than using a new media type for structured cabling systems. To increase the carrying capacity of fiber, the laser light that carries data through fiberoptic glass can be split into different colors, or more precisely, wavelengths, each of which carries a discrete data channel. Today, the technology will support up to 40 different wavelengths. In the near future, 128 channels will be available. The best result of this technological development is that transmission facilities for new wavelengths can be retrofitted onto existing plants that connect to fiber already in the ground, which makes it the easiest way to increase bandwidth. This technology will obviate the requirements of additional fiber and will use the existing optical fiber and connectors. Plastic optical fiberHistorically, plastic optical fiber (POF) has been relegated to lowspeed, shortdistance applications. Recent technical developments of gradedindexed POF have increased bandwidths to 3 GHz/100 meters. But this medium is not endorsed by any standards body because the current technology is limited to a distance of 50 meters at the required bandwidth. Endorsement within a written standard is crucial for market acceptance. It will be perhaps five years before lowcost POF will be mercially available. If and when a standards body sanctions POF, it should offer a more robust system for applications currently served by copper media, at a cost below that of glass optical fiber. Wireless technology Much has been written about the prospect of wireless networking replacing fixedmedia structured cabling systems in the future. Currently, cost and low bandwidth have left wireless technology with approximately 1% of the number of deployed Ethernet ports. The features of wireless networking are beguiling to those who are involved with the design, installation, and maintenance of structured cabling systems. With wireless, there are no more concerns about running cable to inaccessible locations, and no more concerns about cable types. But for all the magic of wireless networking, there are downsides. Although a standard for wireless networking exists IEEE put out by the Institute of Electrical and Electronics Engineers plete interoperability among all WLAN vendors remains unattained. IEEE stipulates an 11Mb/s datatransfer rate. An Australian pany has recently developed a wireless system that claims to support 54Mb/s. In an open office plan, propagation
電大資料相關(guān)推薦
鄂ICP備17016276號-1