Roanoke Times
                 Copyright (c) 1995, Landmark Communications, Inc.

DATE: TUESDAY, January 10, 1995                   TAG: 9501110018
SECTION: EXTRA                    PAGE: 3   EDITION: METRO 
SOURCE: DAVID BUTLER
DATELINE:                                 LENGTH: Medium

HOME-CONTROL STANDARD FINALLY BEGINS TO BEAR FRUIT

A: The Consumer Electronics Bus (CEBus) is a communications standard developed by the Electronic Industries Association. As such, CEBus is a document, not a system. The effort took 10 years and attracted participants from hundreds of companies representing just about every industry that has anything to do with consumer electronics and home systems.

CEBus establishes rules that govern how products communicate with one another over wiring commonly found in the home: 120-volt electrical wiring (Power Line Bus), video cable (Coax Bus) and telephone wire (Twisted Pair Bus). In communications parlance, a wire becomes a bus when it is shared by devices that adhere to a standard protocol.

During the past year, more than a dozen companies demonstrated CEBus-compliant products at industry trade shows. A handful of products are already on the market with dozens more to follow soon. One of the first CEBus products is a unique light switch and dimmer. It not only responds to commands issued by other products but can act as a stand-alone controller.

Power Line Bus (PLBus), the mainstay of CEBus, provides true "plug and play" access to the network - no special preparations are necessary. Commands and other data move at speeds up to 10,000 bits per second - much faster than with previous power line carrier products. The receiving device must acknowledge each command and provide a status report if requested.

Coax Bus (CXBus) relies on twin coaxial cables (type RG6) to distribute audio and video throughout the house. It can handle both digital and analog audio signals. Twisted Pair Bus (TPBus) consists of four pairs of solid-conductor telephone wire (22/24-gauge). It provides network access to sensors and other low voltage devices. TPBus also supports intercoms, computers and electronic telephone systems.

CXBus and TPBus require a modest investment for special wiring and a distribution panel. Depending on the layout and number of outlets, the installed cost will vary from several hundred to about a thousand dollars. Some homeowners may be able to convert unused telephone or video wires to work with CEBus, though not without tradeoffs.

CEBus also sets standards for wireless products that use infrared or radio frequency signals (IRBus and RFBus). Hand-held remotes will be able to communicate directly with products throughout the house by transferring messages onto one of the wired buses. Using a bi-directional remote, the user will quickly be able to check the status of any product on the network.

The next few years will be a transitional period as manufacturers sort out their respective products' roles in the integrated home of the future. Not surprisingly, intelligent systems (e.g., security, whole-house audio and low-voltage controlled lighting) are dominating the first round of CEBus product introductions. CEBus makes it possible for these and other home systems to collaborate, delivering benefits that none could have offered alone.

CEBus is getting a big boost from several utility projects involving tens of thousands of homes. Smart meters, thermostats, cable TV decoders and load control switches are among the products being modified to use CEBus. As the electric utility industry moves toward deregulation and competition, it may end up playing a pivotal role in bringing CEBus and home automation to consumers.

To receive a copy of my CEBus Resource List, please send $1.50 and a self-addressed envelope to David Butler F-443, Department TWN, 14713 Pleasant Hill Road, Charlotte, N.C. 28278-7927. The list includes companies that have introduced or will soon introduce CEBus-compliant products and wiring systems. You'll also receive tips on prewiring your home for CEBus.

Note: David Butler has been a member of the CEBus Technical Steering Committee since 1985 and has written numerous articles on the subject. In the Roanoke area, Lee Hartman & Sons offers CEBus prewiring services.

Q: What is the difference between 75-ohm and 300-ohm antenna wire?

A: 300-ohm wire has two stranded wires separated by a flat insulator. 75-ohm coaxial cable has a single solid wire surrounded by a round foam insulator and braided shield. Coax does a better job conducting UHF signals.