Process of converting digitized data into analog form for a carrier wave. Demodulation transforms data transmitted in analog form back into digital form for computer storage and/or processing. Modems modulate and demodulate computer data for transmission on telephone lines. Fax modems have the added capability of importing facsimiles received over phone lines directly into computer files. Cable TV modems offer transmitting speeds of over five times those of ISDN modems. The term "ricochet modem" is sometimes used to depict a wireless connection of a computer to the Internet. The product Ricochet Modem is brick-sized connector from Metricom Inc. that is a special kind of radio connector to the Internet in metropolitan areas having Ricochet's receivers for Internet connections. The early applications of the Ricochet Modem are reviewed in Mossberg (1996) . (See also ISDN , DSL , MMDS , and ADC ) Downstream (download) refers to the transmission of network datainto your computer from another computer. Upstream (upload) refers to transmission of network data out of your computer into another computer on the network. In other words, messages or data sent to you go downstream and messages or data sent by you go upstream. At the present time the fastest analog modems that convert analog phone line downloads into digital data on your computer (or vice versa for uploads) run at 56 Kbps (56,000 bits per second). Most users, however, are still using 28.8 Kbps modems. An ISDN line doubles capacity to 128 Kbps. The new DSL (Digital Subscriber Line) offered by phone companies increases this up to 6400 Kbps. However, Asymetric Digital Subscriber Line (ADsL) can go up to 6 Mbps downstream and 640 Kbps upstream. ADC Kentrix has a report discussing DSL and ASDL.
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_____ Switched Broadband Key To Future Of E-Commerce____ Bell Atlantic chairman Ray Smith said yesterday at the Internet & Electronic Commerce Conference in New York that the success of Internet-based commerce depends on speed. He then described how his company will provide it: with high-performance "switched broadband" connections that he claims will render technology like ISDN and ADSL obsolete. "Switched broadband will obsolete everything that comes before." Smith said in his speech that Bell Atlantic's bandwidth "end game," lies with next-generation switched broadband technology currently under development and set for deployment in Philadelphia in 18 months. Switched broadband, built on unnamed technology licensed from Lucent Technologies, will offer downstream connect speed of 52 Mbps and upstream connect speed of 3 Mbps, while taking advantage of customers' existing telephone wiring. According to Smith, switched broadband is able to jump the performance hurdles posed by the final 20 yards between buildings and the fiber optic line that ends at the curb. Telephone companies like Bell Atlantic typically bury eight to 10 copper lines instead of just one when installing voice networks. Switched broadband uses devices licensed from Lucent that let data communications take advantage of those extra wires for data transmission, making high-speed connections across the copper. "[Switched broadband] turns that buried copper into gold," Smith said. --Jeff Sweat