Radio commuincation

Radio BroadcastingRadio Broadcasting

Radio has its roots in the Radio has its roots in the Telegraph.Telegraph.

This device was the first This device was the first widely-used form of widely-used form of long-distance long-distance communication.communication.

In 1836, Samuel Morse In 1836, Samuel Morse invented a language of invented a language of dots and dashes that is dots and dashes that is still used today.still used today.


In 1876, Alexander In 1876, Alexander Graham Bell Graham Bell transmitted the human transmitted the human voice over wires for the voice over wires for the first time. first time.

Soon, his invention Soon, his invention moved from the lab to moved from the lab to the home and life the home and life hasn't been the same hasn't been the same since.since.


Most of these Most of these telephones were wired telephones were wired on party lines, which on party lines, which means that many of means that many of your neighbors could your neighbors could listen to your calls.listen to your calls.

All the phones on the All the phones on the party line rang at one party line rang at one time, and each home time, and each home had its own ring pattern.had its own ring pattern.


In 1887, Heinrich Hertz In 1887, Heinrich Hertz demonstrated that demonstrated that electromagnetic waves electromagnetic waves could be transmitted could be transmitted through the air. through the air.

As a result, the term As a result, the term "Hertz" is now used to "Hertz" is now used to specify cycles per specify cycles per second for the second for the frequency of both sound frequency of both sound and radio waves.and radio waves.


In 1883, a dentist named In 1883, a dentist named Mahlon Loomis received Mahlon Loomis received the patent for wireless the patent for wireless telegraphy, buttelegraphy, but

Guglielmo Marconi is Guglielmo Marconi is commonly credited as commonly credited as inventing radio in 1895 inventing radio in 1895 even though there is even though there is credible evidence that credible evidence that other inventors were other inventors were first.first.


Nikola Nikola Tesla demonstrated wireless transmissions during a lecture on the potential of high frequency transmitting in 1891.

In 1893, after continued research, Tesla presented a paper on the basics of radio (wireless telegraph).


Once Marconi patented Once Marconi patented his invention in England, his invention in England, his next step was to sell his next step was to sell it to the marine industry. it to the marine industry.

Soon, the majority of Soon, the majority of oceangoing ships were oceangoing ships were all equipped with his all equipped with his equipment - which made equipment - which made Marconi a very rich man.Marconi a very rich man.


Ship radio operators who Ship radio operators who had never heard had never heard anything but Morse code anything but Morse code received the first radio received the first radio broadcast from Boston in broadcast from Boston in 1906.1906.

It must have seemed like It must have seemed like the Twilight Zone at sea the Twilight Zone at sea when the ships heard when the ships heard Christmas carols coming Christmas carols coming from their radios!from their radios!


In 1912, a tragedy In 1912, a tragedy happened that shook happened that shook the World. The the World. The "unsinkable" luxury "unsinkable" luxury liner, the Titanic, hit an liner, the Titanic, hit an iceberg and sank.iceberg and sank.

The tragedy could have The tragedy could have been worse. Thanks to been worse. Thanks to the new invention of the new invention of radio, about 800 people radio, about 800 people were saved.were saved.


In the early days of radio In the early days of radio there was no way to there was no way to record sound - record sound - everything was everything was performed "live."performed "live."

Although the first sound Although the first sound recording device can be recording device can be traced back to 1855, it traced back to 1855, it was some time before was some time before the concept was applied the concept was applied to radio.to radio.


In 1898, Danish inventor In 1898, Danish inventor Valdemar Poulsen Valdemar Poulsen created the created the Telegraphone, the first Telegraphone, the first practical magnetic practical magnetic sound recorder using a sound recorder using a piano wire as the piano wire as the recording medium.recording medium.

Soon, wire recorders Soon, wire recorders begin to appear on the begin to appear on the American market. American market.


8XK (now KDKA) in 8XK (now KDKA) in Pittsburgh, Pennsylvania Pittsburgh, Pennsylvania is widely credited as the is widely credited as the first radio station in the first radio station in the US, but the truth is thatUS, but the truth is that

other stations preceded other stations preceded 8XK, but Frank Conrad 8XK, but Frank Conrad did start the first daily did start the first daily program on that station.program on that station.


Conrad initially played Conrad initially played music by holding a mic music by holding a mic up to a phonograph.up to a phonograph.

In no time, people were In no time, people were tuning in, and Conrad tuning in, and Conrad became a mini-celebrity.became a mini-celebrity.

Westinghouse, who Westinghouse, who owned the station, took owned the station, took notice and expanded notice and expanded Conrad's operations.Conrad's operations.


Once radio broadcasting Once radio broadcasting was launched, people was launched, people began to realize just how began to realize just how significant this new significant this new medium could be. medium could be.

For example, KDKA, For example, KDKA, broadcast the 1920 broadcast the 1920 Harding-Cox presidential Harding-Cox presidential election returns well in election returns well in advance of the papers. advance of the papers.


The popularity of the The popularity of the new medium enticed new medium enticed people to build their people to build their own personal radio own personal radio stations.stations.

Soon there were too Soon there were too many stations for the many stations for the number of frequencies number of frequencies available on the radio available on the radio dial.dial.


In 1922, another In 1922, another element entered the element entered the picture — broadcast picture — broadcast advertising. advertising.

What was originally What was originally referred to as a “toll referred to as a “toll broadcast” is now broadcast” is now known as a commercial.known as a commercial.

Along with the advent of Along with the advent of ads came sponsors and ads came sponsors and the need for regulation.the need for regulation.


The Congress passed the The Congress passed the Radio Act of 1927, which Radio Act of 1927, which created the Federal created the Federal Radio Commission - FRC. Radio Commission - FRC.

Its purpose was to Its purpose was to oversee the licensing of oversee the licensing of transmitters, assigning transmitters, assigning radio frequencies, call radio frequencies, call letters, and power limits.letters, and power limits.


Call letters for stations Call letters for stations east of the Mississippi east of the Mississippi start with a "W", and start with a "W", and stations west of the stations west of the Mississippi start with Mississippi start with "K." "K."

A few stations were A few stations were licensed before this rule licensed before this rule was put in to effect, so was put in to effect, so there are couple of there are couple of exceptions.exceptions.


In 1934, the FRC was In 1934, the FRC was reorganized into Federal reorganized into Federal Communications Communications Commission or the FCC. Commission or the FCC.

The FCC's regulatory The FCC's regulatory powers were expanded powers were expanded to include telephone and to include telephone and telegraph - and some telegraph - and some years later, television.years later, television.


The FCC reserved some The FCC reserved some nonprofit frequencies for nonprofit frequencies for educational and educational and religious groups.religious groups.

Due to the big-business Due to the big-business bias of the government, bias of the government, these frequencies were these frequencies were the least desirable and the least desirable and were limited in power. were limited in power.


AM stands for amplitude AM stands for amplitude modulation, and ranges modulation, and ranges from 535 to 1705kHz.from 535 to 1705kHz.

Kilohertz are thousands Kilohertz are thousands of cycles per-second of of cycles per-second of electromagnetic electromagnetic energy.energy.

These are the numbers These are the numbers you see on your AM you see on your AM radio dial.radio dial.


The tan area at the left are AM radio waves and The tan area at the left are AM radio waves and are at a lower frequency than FM radio or TVare at a lower frequency than FM radio or TV

Stations can be placed every 10kHz along the Stations can be placed every 10kHz along the AM band so there are 117 channels available.AM band so there are 117 channels available.


The signals of most AM The signals of most AM stations are limited in stations are limited in their range, so the same their range, so the same frequencies can be used frequencies can be used many times as long as many times as long as they are separated.they are separated.

This is how we can have This is how we can have nearly 5,000 AM radio nearly 5,000 AM radio stations in the US on 117 stations in the US on 117 different frequencies.different frequencies.


Modulation refers to how Modulation refers to how sound is encoded on a sound is encoded on a radio wave (called a radio wave (called a carrier wave) so that the carrier wave) so that the sound can be detected sound can be detected by a radio receiver.by a radio receiver.

The top drawing is not The top drawing is not modulated by any sound modulated by any sound so there would be so there would be silence on your radio.silence on your radio.


FM or frequency FM or frequency modulated radio and modulated radio and TV waves act TV waves act differently than AM differently than AM radio waves.radio waves.

The FM radio band The FM radio band goes from 88 to 108 goes from 88 to 108 MHz (megahertz, or MHz (megahertz, or millions of cycles per millions of cycles per second). second).


FM stations must be FM stations must be 200kHz apart which 200kHz apart which means that there's means that there's room for 200 FM room for 200 FM stations on the FM band.stations on the FM band.

FM stations don't have FM stations don't have nice round numbers like nice round numbers like 820 or 1240. Instead, an 820 or 1240. Instead, an FM station may be at FM station may be at 88.7 on the dial.88.7 on the dial.


FM and TV signals travel FM and TV signals travel in a straight line and in a straight line and don't bend around the don't bend around the earth as AM waves do. earth as AM waves do.

The farther away from The farther away from the FM or TV station the FM or TV station you are, the higher you you are, the higher you have to have an have to have an antenna to receive the antenna to receive the signal.signal.


Frequency relates to the Frequency relates to the pitch of a sound - how pitch of a sound - how high or low it is. A 20 Hz high or low it is. A 20 Hz frequency sound is frequency sound is extremely low-pitched - extremely low-pitched - almost a rumble.almost a rumble.

A 20,000 Hz sound is the A 20,000 Hz sound is the highest pitched sound highest pitched sound that can be imagined.that can be imagined.


A person with very A person with very good hearing will be good hearing will be able to hear sounds able to hear sounds from 20-20,000 Hz.from 20-20,000 Hz.

The common range The common range used for FM radio and used for FM radio and TV is from 50 to TV is from 50 to 15,000 Hz. and AM 15,000 Hz. and AM radio is below this radio is below this range.range.


The average US The average US resident listens to 22 resident listens to 22 hours of Radio per hours of Radio per weekweek

In the US, Radios out-In the US, Radios out-number people 3 to 1number people 3 to 1

In most countries, In most countries, Radio continues to be Radio continues to be the primary source of the primary source of news and informationnews and information

Radio commuincation

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