Kenneth C. Laudon,Jane P. Laudon Management Information System 12th Edition pdf

Microwave

systems, both terrestrial and celestial, transmit high-

frequency radio signals through the atmosphere and are widely used for

high-volume, long-distance, point-to-point communication. Microwave sig-

nals follow a straight line and do not bend with the curvature of the earth.

Therefore, long-distance terrestrial transmission systems require that trans-

mission stations be positioned about 37 miles apart. Long-distance transmis-

sion is also possible by using communication satellites as relay stations for

microwave signals transmitted from terrestrial stations. 

Communication satellites use microwave transmission and are typically

used for transmission in large, geographically dispersed organizations that

would be difficult to network using cabling media or terrestrial microwave, as

well as for home Internet service, especially in rural areas. For instance, the

global energy company BP p.l.c. uses satellites for real-time data transfer of oil

field exploration data gathered from searches of the ocean floor. Using geosyn-

chronous satellites, exploration ships transfer these data to central computing

centers in the United States for use by researchers in Houston, Tulsa, and

suburban Chicago. Figure 7-7 illustrates how this system works. Satellites are

also used for home television and Internet service. The two major satellite

Internet providers (Dish Network and DirectTV) have about 30 million

subscribers, and about 17 percent of all U.S. households access the Internet

using satellite services (eMarketer, 2010).

FIGURE 7-7

BP’S SATELLITE TRANSMISSION SYSTEM

Communication satellites help BP transfer seismic data between oil exploration ships and research

centers in the United States.

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Chapter 7

Telecommunications, the Internet, and Wireless Technology

257

Cellular systems also use radio waves and a variety of different protocols to

communicate with radio antennas (towers) placed within adjacent geographic

areas called cells. Communications transmitted from a