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AT＆T paradyne公司最近宣称与AT＆T贝尔实验室研制出新的对称数字用户环路(SDSL—Syme tric Digital Subscrb Line),作为不对称数字用户环路(ADSL—Asymmetric Digital subscriber Line)技术的补充。ADSL从电话网络到远端用户侧提供1.5Mbit/s或2Mbit/s,最大可达6Mbit/s的信道,反向则提供16或64Kbit/s低速率的信道。SDSL提供双向由128kbit/s到T1/E1(1.544Mbit/s/2.048Mbit/s)的信道。Paradyne公司的ADSL采用对载频幅度与相位同时调制(CAP)技术,可在现有铜线上提供点播电视等业务。SDSL可以支持远程学习,远端LAN(局域网)接入,远程工作,高速Internet(一种国际计算机网络)接入以及交互
AT & T paradyne recently announced a new symmetrical digital subscriber loop (SDSL-Symmetric Digital Subscrb Line) with AT & T Bell Laboratories to complement ADSL-Asymmetric Digital Subscriber Line technology. ADSL from the telephone network to the remote user side to provide 1.5Mbit / s or 2Mbit / s, up to 6Mbit / s channel, the reverse provides 16 or 64Kbit / s low rate channel. SDSL provides bidirectional channels from 128 kbit / s to T1 / E1 (1.544 Mbit / s / 2.048 Mbit / s). Paradyne’s ADSL uses Carrier Frequency Amplitude and Phase Simultaneous Modulation (CAP) technology to provide on-demand television on existing copper lines. SDSL can support distance learning, remote LAN (local area network) access, remote work, high-speed Internet (an international computer network) access and interaction