Using cable Internet services for the first time can be a breathtaking experience. Images and text flash before your eyes instantly①. Full-motion video and audio play without jitter. When you see this， you realize that this was how the Internet was meant to be. Even for Internet oldtimers， it’s like a whole new world.
The cable television network has emerged as the early leader in providing such high-speed data access in the home. With more than a million cable modern subscribers② now in North America， the system has matured from a string of experimental deployments in 1995 to a mainstream service available in most major cities.
Internet access over cable runs at speeds up to 100 times those of the traditional dial-up world. This raw speed is the catalyst③ producing the dramatic④ change to typical Internet services. And the connection is “always on，” enabling users to call up a site immediately as the spirit moves them. Gone are the days of having to log in to the network.
How does cable achieve these data rates？ In the late 1980s and early 1990s cable operators started deploying fiber optics in their networks. Cable companies ran fiber out to individual neighborhoods and made use of existing network of coaxial cable to reach the “last mile” to each home. The optical⑤ fibers connect the cable operator’s central facility (the “head end”) to each neighborhood area (the “node”). Fiber has greatly increased the capacity⑥ and reliability of cable TV networks. With a cable Internet connection， data occupy the space of one TV channel. Tune to this channel with your TV， and you’ll see only static， but connected to your cable modem it becomes a data stream flowing at about 40 megabits per second (Mbps)， which can then be relayed to your personal computer at rates up to 10 Mbps. the fiber network also allow signals to be sent back from the home to the head end， making telephone and interactive vidio services possible.
① instantlyadv. 立即地， 即刻地
② subscribern. 订户， 签署者， 捐献者
③ catalystn. 催化剂
④ dramaticadj. 戏剧性的， 生动的
⑤ opticaladj. 眼的， 视力的， 光学的
⑥ capacityn. 容量， 生产量， 容量， 智能
通过有线电视上互联网
初次使用有线电视上互联网可以成为一次极为刺激的经历。图片和文本在你眼前飞快地闪过，图像和声音流畅地播放。当你看到这一切的时候，你会明白这才是因特网应该有的样子。就算对上网老手来讲，这也是一个全新的世界。
在提供这种家庭高速数据接入方面，有线电视已占得先机。在北美，已经有100多万个用户在使用有线调制解调器。在经过了1995年一连串的试验性配置之后，到现在多数大城市中都可以得到主流服务，整套系统已经成熟。
通过有线电视网上网其速度之快是传统拨号方式的100倍。速度快成了导致传统网络服务发生巨大变化的催化剂。有线上网永不下线。这使得用户可以随心所欲地拜访站点，而免去了登录之苦。
有线电视网的数据传输速率怎么会这么快呢？从20世纪80年代末到90年代初，有线服务商开始在网络中配置光纤。有线电视公司把光纤铺到小区，再利用现有的同轴电缆网络深入到千家万户。光纤则将有线电视服务商的中心装置（始端）和小区（节点）连接起来。光纤大大提高了有线电视网的性能和可靠性。网络数据占据电视的一个频道。当你调到这个频道的时候，只能看到静止的画面，但是如果连上你的有线调制解调器，它就会变成速度为每秒约40兆位的数据流。该数据流可以再以每秒10兆位的速度传入个人电脑。光纤网络还允许将信号上传回始端，从而实现电话和互动电视功能。
