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Compare and contrast 2 talk radio station

Three revolutions have come via the airwaves. Radio has transformed society three times, not to mention giving birth to the entire field of electronics. Perhaps no invention of modern times has delivered so much while initially promising so little.

His equations explained light as one form of electromagnetic radiation and predicted that there should be many other forms, invisible to the human eye. The principle behind radio transmission is simple. Electrons moving through a wire create a magnetic field. Place another wire near the first and electrons will start to move in the second wire too. The signal travels between the wires because the magnetic field formed by the first wire—the transmitter—creates an electric field in space, which in turn creates a magnetic field, and so on, moving outward at the speed of light.

When the second wire—the receiver—picks up that signal, the field is converted back into the motion of electrons, detectable as an electric current. In order to carry information, the transmitted signal has to vary over time.

The easiest way to do this is simply to stop and start the current in the first wire, sending a message as a series of pulses. The flamboyant Serbian-born engineer Nikola Tesla followed that approach and transmitted a radio signal across a short distance in 1893. Soon after, Italian inventor Guglielmo Marconi accidentally discovered that grounded antennas could send signals more than a mile instead of a few hundred yards.

He had inadvertently been using Earth to propagate a radio signal close to the ground.

How Radio Changed Everything

With further refinements, he found a way for ships to talk to each other using Morse code—the quintessential pulsed signal—and in 1896, just compare and contrast 2 talk radio station, he traveled to England and set up a radio company, British Marconi.

World events quickly proved the value of this work. In 1905 the Japanese navy all but destroyed the Russian fleet at the Battle of Tsushima, in part because of radio equipment the Japanese bought from Marconi.

He saw the airwaves as useful for point-to-point traffic between ships at sea and other clients untethered by cables, but compare and contrast 2 talk radio station was about it.

Douglas, a radio historian at the University of Michigan. The next big step was finding a way to manipulate radio waves so they could carry more than dots and dashes.

Switching from pulses to continuous waves provided the key. Amplitude modulation superimposes a varying audio wave onto a radio wave with a fixed frequency: Where the audio wave peaks, the modulated radio wave is at its highest intensity, and where the audio wave has a trough, the radio wave is at its lowest intensity.

Fessenden ultimately earned money and fame from his invention. On the other hand, American radio engineer Edwin Howard Armstrong, regarded by many radio cognoscenti as the greatest of them all, is today almost forgotten. He noticed that by varying wave frequency instead of amplitude, stations could avoid the interference that often corrupted AM transmissions.

The result was frequency modulation—FM radio. In this case, a peak in the audio wave is represented by an increase in the frequency of the radio wave, while a trough is represented as a decrease in frequency. A lifetime of patent lawsuits crushed Armstrong emotionally, and he committed suicide in 1954.

Although its commercial potential today seems obvious, broadcasting was actually kick-started by amateurs: His show aired every Wednesday and Saturday—some sports scores, some talk, but mostly music. When Conrad ran out of records, he struck a deal with a local store to supply him with more in return for on-air promotions. These are believed to be the first radio ads. To bring some order to the growing number of broadcasters who were appropriating their own radio wavelengths, or frequencies, the government created the Federal Radio Commission.

Radio broadcast licensing was born, and a virtual real estate boom—the competition for slices of the radio band—began. The amateurs who stayed amateurs soon found themselves being moved by regulators to less desirable locations farther up the radio spectrum.

Roughly speaking, lower frequencies are cheaper to use than higher frequencies because they require less precise equipment, an important consideration for an industry that wanted to market radio receivers to the masses. Soon the armed forces also wanted their slice of the radio spectrum. Military use of radio communications may have begun at Tsushima, but after World War I it expanded enormously. Radar began with the observation that lightning gives off a radio signal, and Scottish engineer Robert Watson-Watt, working as a meteorologist, thought he could exploit this phenomenon to warn pilots of approaching storms.

Using a directional antenna, he found he could scan the skies and pick up lightning. Then he realized that if he transmitted radio pulses as well as listened to them, he could bounce a signal off a target—an approaching aircraft, for example.

By measuring how long it took for echoes to return to the antenna, he could know not only the bearing of the target but also its range. Watson-Watt promptly contacted the British Air Ministry in 1935. After some initial skepticism, the ministry embraced the invention.

As World War II began, 19 radar stations were in operation. FM signals, in contrast, have a wavelength of about 10 feet, and AM signals run about 1,000 feet.


The first decades of the 20th century also saw video being transmitted over the airwaves. The first television system, developed in the U. He started broadcasting TV using just 30 scan lines per video frame—enough to send a rough image but crude compared with the 484 lines per frame used in U.

The televisions in use today trace their heritage to American inventor Philo Farnsworth, who created the first all-electronic television system in 1928. Over the years, more users have elbowed their way onto the radio spectrum as new technologies arrive. Some need ultrahigh frequencies that allow more information to be transmitted per second. It is no surprise to find a data networking technology like Wi-Fi operating at 2.

Baby monitors operate at 49 megahertz. FM radio is positioned between 88 MHz and 108 MHz, and users as diverse as police dispatchers, air traffic controllers, and cell phone callers all have their own bands. At the upper end of the radio spectrum come microwaves, used for data transmission, radar, and of course, cooking. Your microwave operates at almost the exact same frequency as your Wi-Fi connection.

Engineers keep finding more and more uses for radio, and frequencies never seem to end up on the scrap heap. You can even find Morse code transmissions still on the air.

In 2009 analog broadcast TV will stop in the United States—but bidders are already lined uppreparing extravagant new uses for those slices of spectrum.