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众所周知,ADSL(AsymmetricalDigitalSubscriberLoop,非对称数字用户环路)是一种通过现有普通电话线为家庭、办公室提供Internet宽带数据接入服务的技术,也是目前国内应用最为广泛的Internet宽带接入方式之一。ADSL能够在现有的铜质双绞线,即普通电话线上提供高达8Mbps的高速下行速率,这远高于之前曾经风靡一时的128KbpsISDN的速率;而其上行速率为1Mbps,传输距离可达3km～5km。ADSL技术的主要特点是可以充分利用现有的铜缆网络(电话线网络),在线路两端加装ADSL设备即可为用户提供Internet宽带接入服务。ADSL的另外一个优点在于它可以与普通电话共存于一条电话线上,在一条普通电话线上接听、拨打电话的同时进行ADSL数据业务的传输。
It is well-known that Asymmetrical Digital Subscriber Loop (ADSL) is a technology that provides Internet broadband data access service for families and offices through existing ordinary telephone lines and is also one of the most widely used Internet broadband access methods in China at present . ADSL provides high-speed downlink speeds of up to 8 Mbps over existing copper twisted pair, plain phone lines, which is much faster than the once-ubiquitous 128-Kbps ISDN; with an upstream rate of 1 Mbps and a transmission distance of up to 3 km ~ 5km. The main feature of ADSL technology is that it can make full use of the existing copper network (telephone line network), and install ADSL equipment at both ends of the line to provide Internet broadband access service for users. Another advantage of ADSL is that it can coexist with a regular phone on a phone line, answering on an ordinary phone line, making phone calls, and transmitting ADSL data services.