Roanoke Times
Copyright (c) 1995, Landmark Communications, Inc.
DATE: TUESDAY, December 6, 1994 TAG: 9412070001
SECTION: EXTRA PAGE: 6 EDITION: METRO
SOURCE: DAVID BUTLER
DATELINE: LENGTH: Medium
A: Although 100 feet is within the reach of most cordless phones, other factors affect reception and sound quality. Nearby radio and electrical fields can cause static and interference while walls, trees and other obstructions can severely limit a phone's range. Fluorescent lights, power tools and aluminum siding are some of the worst offenders.
Until recently, just about every cordless phone operated between 46 and 49 megahertz (MHz). In order to relieve the traffic jam, the FCC opened up the 900-MHz band to consumer products. Cordless phones were among the first products to take advantage of the new rules. By year's end, nearly two-dozen 900-MHz phones will have debuted.
Besides having less traffic to contend with, 900-MHz phones are less sensitive to many types of interference. Most models are designed to scan for a clear channel (from as many as 100) each time you pick up the handset. Some models automatically switch channels in the midst of a conversation if the voice signal begins to degrade.
High-frequency phones have one additional advantage: unprecedented range. Although manufacturers are careful not to cite specific distances (radio reception is heavily dependent on the environment), they readily claim their 900-MHz phones will operate four to eight times farther than a 46/49 MHz model.
Prices have dropped sharply since the first 900-MHz phones entered the market. Some models can now be purchased for under $200. Cordless phones are sometimes classified according to how the handset and base communicate with one another: analog, digital or spread spectrum (a special class of digital). Assume that a model is analog unless the product literature explicitly states otherwise.
The first thing you'll notice when using a digital phone is the absence of any hiss. You might even forget you're talking on a cordless phone! This makes an out-of-range alert tone a necessity. Digital phones offer another important advantage: It's nearly impossible for someone to listen in on your conversation. Casual eavesdropping is more common than you think.
Those who need maximum range should consider a spread-spectrum phone. The most powerful models can transmit more than one-half mile in an open field! (The FCC allows spread-spectrum transmitters to operate at much higher power levels than conventional "narrowband" transmitters.) Furthermore, spread spectrum is highly immune to interference and is virtually hacker-proof.
Standard features on 900-MHz phones include two-way intercom and paging, memory dial and digital security codes. Two-line versions are also available. One model even has a speakerphone and separate keypad in the base unit, making it possible to answer or place calls from the base.
Battery technology has also improved in recent years - you can converse up to four hours on a single charge. In standby mode, the handset can maintain its charge for several days. Some models come with a spare battery pack so that one can be charged while the other is in use. An interesting variation takes full advantage of the spare, using it to operate the base during a power outage.
To receive a complete list of manufacturers of 900-megahertz cordless phones, please send $1.50 and a self-addressed envelope to David Butler F-433, Department TWN, 14713 Pleasant Hill Road, Charlotte, N.C. 28278-7927. The list includes toll-free phone numbers and a description of each company's products.
Q: Heavy-gauge stranded cable is much more expensive than the equivalent solid conductor cable. Is there a reason why I shouldn't use solid wire to connect a pair of remote speakers?
A: Although solid conductor cable will work, sound quality will suffer. Stick with high-quality stranded cable.
by CNB