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Radio

The Future Of Radio

Radio broadcasting now includes a newer, better digital system known as DAB, digital-audio broadcasting. Early tests indicate that a switch to digital imparts compact-disc quality to radio programming. There are two possible modes for DAB. In Europe, completely new stations on a different band of frequencies is favored. In the United States it seems probable that digital information will transmitted as information superimposed on the programming modulation now used. The digitized audio can be so much lower in power than the "main" programming that it will be inaudible to listeners with analog receivers. Early program tests of this system have been successful and increases in audio quality have been significant.


Resources

Books

The 1995 ARRL Handbook. The American Radio Relay League, 1995.

Hobson, Art. Physics: Concepts and Connections. New York: Prentice-Hall, Inc., 1995.

Jacobs, George, and Theodore J. Cohen. The Shortwave Propagation Handbook. Cowan Publishing Corp., 1970.

Ostdiek, Vern J., and Donald J. Bord. Inquiry Into Physics. St. Paul: West Publishing Company, 1995.


Other

Now You're Talking. The American Radio Relay League, 1994.


Donald Beaty

KEY TERMS


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Antenna

—An electrical conductor used to send out or receive radio waves.

Capacitor

—Electrical component that cancels magnetic property of wire.

D Layer

—Arbitrary designation for the lowest layer of the ionosphere.

Electric field

—The concept used to describe how one electric charge exerts force on another, distant electric charge.

Electron tube

—Active device based on control of electrons with electric fields.

F layer

—Arbitrary designation for the highest layer of the ionosphere.

Gamma ray

—Electromagnetic radiation with the shortest wavelengths.

Inductor

—Electrical component that adds magnetic property to wire.

Infrared light

—Light with wavelengths longer than those of visible light.

Ionized

—Missing one or more electrons, resulting in a charged atom.

Magnetic field

—Effect in space resulting from the motion of electric charge.

MegaHertz

—One million cycles per second; MHz.SI abbreviation for MegaHertz.

Morse code

—Dot and dash code used to send messages over telegraph wires.

Resonance

—The enhancement of the response of a system to a force, when that force is applied at a particular frequency known as the resonant frequency.

Selectivity

—Receiver property enabling reception of only wanted signals.

Sensitivity

—Receiver property enabling reception of weak signals.

Standing wave

—A stationary pattern of activity resulting from interference.

Sunspot

—Cooler and darker areas on the surface of the sun. They appear dark only because they are cooler than the surrounding surface. Sunspots appear and disappear in cycles of approximately 11 years.

Telemetry

—Engineering and scientific measurements transmitted by radio.

X ray

—Electromagnetic radiation of very short wavelength, and very high energy.

Additional topics

Science EncyclopediaScience & Philosophy: Quantum electronics to ReasoningRadio - The History Of Radio, Radio And The Electromagnetic Spectrum, How Radio Signals Are Created, Modulation - Demodulation