A line drive is roped into right field and the tying run on second races towards home. As the ball skips into the outfield, the right fielder scoops up the ball and hurls it home. The ball is intercepted by the second baseman and he in turn quickly heaves it toward the catcher, who proceeds to tag out the runner and the vanquished visitors lose yet again.

No, this isn’t a tale of the woefully unlucky Boston Red Sox or Chicago Cubs. The scenario illustrates the concept behind the use of signal boosters for radio communications.

Similar to the velocity loss of a baseball traveling a certain distance, a radio frequency can lose power or clarity as its course is interrupted by natural and man-made obstacles. Hence the fundamental baseball rule of “hitting your cut-off man” becomes essential to the business of communications. The cut-off man in the case of industrial radios is the signal booster or repeater amplifier. This stationary device acts as the relay point where a radio frequency is received and retransmitted at a higher power level. This retransmission becomes essential as society and its technological advances require communications through physical impediments.

By allowing a broader range of usage and few sanctions, the FCC has opened the doors for

more efficient radio communication networks.

As society continues to expand and progress, the need to communicate also must meet the changes in people’s daily lifestyles. Major cities often function with some type of mass transit, such as Washington D.C.’s Metro, entailing the use of vast networks of underground trains. The ability of Metro and the city government to ensure safety and assistance to its travelers is essential. Industrial radios must be able to provide constant and clear lines of communications within the tunnel system. Problems arise when radio frequencies are impeded by the concrete and metal materials of the structure and the inability of radio frequencies to travel through the ground.

The Federal Communications Commission on May 17 adopted a proposal to expand the use of signal boosters beyond the 10 frequency pairs now allocated for airport terminal operations. The proposal addresses the use of signal boosters in connection with common carrier paging systems, one-way and two-way private land mobile radio systems and multiple address systems operated in the private microwave radio service. Within each radio system, two types of signal boosters will be permitted: narrowband (Class A), which will amplify only those specific frequencies intended to be retransmitted, or broadband (Class B), which amplify any and all of the frequencies that pass through its filter. The recently adopted proposal enables owners of radio systems to use signal boosters to maximize their radio systems while alleviating the problem of weak coverage due to natural and man-made obstructions. Under the rules currently in place, licensees desiring to add a signal booster to their land mobile or multiple address radio systems generally require a waiver of the commission’s rules. The waiver process itself is costly and time-consuming.

In its proposal, the FCC has taken a moderately laissez-faire approach toward the use of signal boosters, mandating only a few restrictions. The proposal would limit the power of all signal boosters to 500 milliwatts and the range of the signal booster would be confined to the service area of the radio system which the signal booster serves. The responsibility of avoiding and alleviating interference problems will fall upon the shoulders of the owners of the signal boosters. Allen Telecom Group suggested requiring the use of directional antennas in conjunction with the signal boosters; however, the FCC has tentatively ruled that the choice of antenna will be determined by the licensee. The recently adopted proposal clearly provides licensees with the autonomy to maximize their systems without government intervention. By allowing a broader range of usage and few sanctions, the FCC has opened the doors for more efficient radio communication networks.

The original intent of signal boosters was to provide extra safety precautions within airport terminals. The need to ensure safety and efficiency within natural resource mines led to the production of signal boosters by a company called TX RX Systems Inc. TX RX created the first UHF two-way signal booster in 1978 to be used by a coal mine in Illinois. The inability of radio waves to penetrate underground necessitated the use of signal boosters. Ever since, signal boosters have proven to be a reliable and consistent means of communication between workers and managers. Booster use has expanded into many of the major U.S. and world cities. The effectiveness of boosters to maximize the use of radio systems, coupled with augmenting efficiency and the safety of workers and commuters, has made signal boosters an invaluable asset to industrial society. The FCC’s proposal is intended to address the immediate needs of an ever-growing population and will help society keep pace with the technology that has entered into the computerized and industrialized economy.

Global technology, mass transit and communication lines are fundamental in maintaining progress and supporting the economics of world markets. The overcrowding of city streets coupled with the convenience of mass transit systems has directed many commuters underground, to the skies and to the seas. This contemporary migration has, of course, spurred a greater demand for mineral resources and raw materials for building structures and has increased the work force of maintenance workers and others who earn their living in enclosed structures.

The recently completed English “Chunnel,” O’Hare International Airport, the San Francisco Bay Area Rapid Transit System and the subway system in Caracas, Venezuela, illustrate some of the current uses of signal boosters. The uses stretch far beyond the public sector, such as with the original two-way UHF system installed in the Illinois mine. The largest copper mine in the world, located in Chile, employs signal boosters to radiate the weakened radio frequencies from one section of the mine to the next.

As society progresses further into the computer and digital age, the need for enhanced industrial radio communication systems must and will match the same pace. The recently adopted FCC proposal to permit the expanded use of signal boosters beyond airport terminals is both opportune and addresses the problem of obstacles, natural or man-made. Communications via radio have become vital in upholding the economic and industrial sectors of the society. By eliminating the process of requesting a waiver to install and operate signal boosters, the FCC has simplified the ever-present problem of weak transmissions due to building structures, materials or geographic terrain. The easy access to signal boosters for any licensee with a one-way or two-way private land mobile system, a common carrier paging system or a private multiple address radio system will benefit both the public and private sector.

As commuters stream in and out of underground subway stops, the concept of industrial radios maintaining their lifestyles and safety is often disregarded or unnoticed. Frequently, the fundamentals are overlooked. Yet, barriers and obstacles created or naturally occurring always will be an impediment, and runners on second are sometimes too fast for a right fielder to gun down.

Minh Day is an intern for the Industrial Telecommunications Association Inc. During his two-year internship, he has assisted the frequency coordination and licensing/information services departments.


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