Broadband Telecommunications

Overview
On this level you encounter digital broadband in the form of Digital Subscriber Loop (DSL) and Cable Modems. Review these well, and explore the possibilities that Fiber to the Home may offer.

xDSL (Digital Subscriber Loop)

 * Use special modems at either end of local phone line
 * Not available to everyone because of distance factors
 * Typically used for home or small office
 * Many types including: asymmetric, rate adaptive, very high data rate, high bit rate, symmetric or single line
 * Transmission
 * DMT (Discrete Multi Tone): 247 channels
 * CAP (Carrierless Amplitude and Phase): three distinct bands with an upstream, downstream, and talking over the telephone channel

Cable Modem

 * Channels are shared (up to 1000 households on a cable modem termination system), homes share a node that is connected via high-speed fiber-optic lines to a cable facility
 * Cable TV networks are not built for bi-directional transmission
 * Cable modem at customer premisesCable_Modem.jpg
 * Provides ethernet connection to PC or a hub
 * Asymmetric channel
 * Feeds provide cable programming and Internet access
 * Homes --> Nodes --> Heads
 * Parts
 * Tuner: connects to CATV outlet
 * Demodulator: converter and error correction
 * MAC (Media Access Control): between receive and transmit paths
 * Interface: ethernet, USB, PCI bus, etc.

Fiber to the Home

 * Not widely available
 * Better security than DSL and cable modems
 * Less equipment, better traffic, can handle more information
 * Active (using switches) or passive (using splitters) systems
 * Common in Hong Kong, South Korea, and Japan

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