History

It was a miracle how the radio was able to send sound and voices across a radio- a Christmas miracle. Instead of hearing dots and dashes of Morse code, these listeners heard "Silent Night" played by a violin. It was Christmas Eve, 1906, and this transmission was one of the first transmitted sounds.

Eleven years before the famous Christmas broadcast, Guglielmo Marconi, an Italian inventor, sent the first "wireless" transmission with his new invention. In 1911he sent a transmission across the Atlantic Ocean, from England to Newfoundland.

Making use of the high-frequency alternator Canadian-born physicist Reginald A. Fessenden made his historical Christmas Eve broadcast, transmitting human speech.

Another early transmission took place when Lee de Forest, inventor of a type of vacuum tube called a triode, aired programs from New York's Metropolitan Opera House. In 1916, a Westinghouse engineer named Frank Concord played records for his friends over the air, and the idea of the radio as a public medium took shape.

An executive at Westinghouse heard about Concord's broadcast and realized its potential. Here was a medium available to the masses- a huge potential audience. An audience that would listen to radio broadcasts with radios made and sold from Westinghouse.

In 1920, Westinghouse's KDKA began regular broadcasts. That same year it aired the results of the 1920 presidential election before the results could be read in the paper. This caused a sensation and is considered the first professional broadcast.

How the Radio Works

We will start off with the microphone. Sound vibrations leave a singer or host's mouth. The higher the pitch of the sound from the singer, the higher the frequency, or number of vibrations in an amount of time. The sound enters the microphone, where it is changed into a weak signal. This weak signal from the microphone is amplified from an amplifier. This additional height, or amplitude, indicates that the signal has more power.

Now the wave generator creates high-frequency radio signals. The frequency of this signal is many times greater than the frequency of the audio wave. This signal will "carry" the audio signal over the air. The carrier signal height is altered, or modulated, to reflect changes in the signal's height or amplitude. Notice how a copy of the audio wave is on the upper and lower halves of the carrier wave.

The signals travel to the antenna. The signal creates a corresponding electromagnetic field - a radio wave. This radio wave moves outward in all directions. The receiving antenna is an antenna that picks up the radio wave. If the antenna is far from the transmitter then the signal is very weak. The amplifier amplifies the weak signal. Then the radio signal is split in half. Since both halves of the signal contain the same audio information, only half of the signal is needed. The signal is fed through a filter. This removes the carrier wave from the signal. What remains is the audio signal. The audio signal causes the radio speaker's diaphragm to vibrate, which makes sound waves.

How Stations Become Stations and How They Are Named

To become a station the FCC (Federal Communication Commission) decides who gets to use a frequency for what purpose. After they approve you, you become a station. When you hear the radio names like 91.5 FM WRKX The Rock, what does that mean? Well it means you are listening to frequency 91.5 megahertz with FCC assigned call letters WRKX. Megahertz means- millions of cycles per second, so the frequency is 91,500,000 cycles per second. Your FM radio can tune to frequencies of 88-108 megahertz. On AM radio instead of Megahertz it has Kilohertz which means- thousand of cycles per second. So if the frequency is 535 it is 535,000 cycles per second. The AM radio can tune in frequencies of 535-1,700 kilohertz.

Uses

There are many uses for radio, but the main use of a radio is for entertainment. Many people listen to radio stations every day. Listening to talk shows, music, and sports. Another use is for the military. When soldiers need orders or who goes on the front line they mostly get them from radio.

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