電子信息工程外文翻譯--綜合布線的未來(lái)適用于畢業(yè)論文外文翻譯中英文對(duì)照-在線瀏覽
2025-03-06 02:23本頁(yè)面
【正文】 gths, 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 of the radio waves may be limited to distances of 200 feet to 500 feet. In a closedwall office environment, propagation may be limited to as little as 100 feet. Undoubtedly, the cost of wireless networking will be reduced and the bandwidth will increase. Wireless networking can serve admirably in numerous applications. Coaxial Coaxial cable has been the medium of choice for wideband applications ranging from highfidelity audio to television to baseband and broadband munications. Coaxial cable was the primary media for 10Base5 and 10Base2 Ethernet. The advent of higherbandwidth UTP cable and connector technology replaced coaxial cable in mercial networks and has relegated its primary use to legacy networks and cable television. Cost considerations Numbers being what they are, one cannot just look at the cost of materials when making a purchasing decision. The applications to be run and the anticipated requirements must be factored into any decision. For instance, Category 5 cable is characterized at frequencies to 100 MHz, whi
電大資料相關(guān)推薦
鄂ICP備17016276號(hào)-1