le industry is a force to be reckoned with and upgrades to the original network are underway. This is a crucial activity that will ensure the success of the industry's ambitious business plan and provide a competitive balance for the traditional telcos. The Cable Network The traditional cable network is an analog system based on a tree-like architecture. The headend, which serves as the signal origination point, serves as the signal aggregation facility. It collects programming infor- Downloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2004 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Access Technologies Access Technologies Figure 6-6 Satellite receive antennas at cable headend facility Figure 6-7 1" Rigid Coax Layout of Head End typical cable distribution network "Semi-Rigid 1/4" Flexible Coax mation from a variety of sources including satellite and terrestrial feeds. Headend facilities often look like a mushroom farm; they are typically surrounded by a variety of satellite dishes (see Figure 6-6). The headend is connected to the downstream distribution network by one-inch diameter, rigid coaxial cable, as shown in Figure 6-7. That cable delivers the signal-usually a 450 MHz collection of 6 MHz channels-to a neighborhood, where splitters divide the signal and send it down half- inch diameter, semi-rigid coax that typically runs down a residential street. At each house, another splitter (see Figure 6-8) pulls off the signal and feeds it to the set-top box in the house over the drop wire, a local loop of flexible quarter-inch coaxial cable. Downloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2004 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Access Technologies Chapter 6 Figure 6-8 Signal splitter in residential cable installation While this architecture is perfectly adequate f