of each pair to a home or business is actually made. To sim- plify the process of installation when the time comes, the cable's wire pairs are periodically terminated in terminal boxes (sometimes called B- Boxes) installed every block or SO. As we discussed in Chapter 3, there may be multiple appearances of each pair on a city street, waiting for assignment to a customer. When the time comes to assign a particular pair, the installation technician will simply go to the terminal box where that customer's drop appears and cross-connect the loop to the appear- ance of the cable pair (a set of lugs) to which that customer has been assigned. This eliminates the need for the time-consuming process of splicing the customer directly into the actual cable. Unfortunately, this efficient process also creates a problem. While the customer's service has been installed in record time, there are now unter- minated appearances of the customer's cable pair in each of the terminal boxes along the street. While these so-called bridged taps present no problem for analog voice, they can be a catastrophic source of noise due to signal reflections that occur at the copper-air interface of each bridged tap. If DSL is to be deployed over the loop, the bridged taps must be removed. And while the specifications indicate that bridged taps do not cause problems for DSL, actual deployment says otherwise. To achieve the bandwidth that DSL promises, the taps must be terminated. Splices and Gauge Changes Splices can result in service impairments due to cold solder joints, corro- sion, or weakening effects caused by repeated bending of wind-driven aerial 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 Gauge changes tend to have the same effects that plague circuits with unterminated bridged taps: When a signal traveling down a wire of one