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Foundations of Radio

Radio Lecture #1

Drew Hamilton

on 7 March 2011

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Transcript of Foundations of Radio

Foundations of Radio
The average U.S. citizen listens to radio 22 hours a week.
For people in most countries of the world radio represents the number one source of news and information.
Radio’s Roots:
2 inventions are mother and father of radio
The Telegraph
The Telephone
The Telegraph
The first widely-used electronic form of communication
Telegraphy is the long distance transmission of written messages without physical transport of letters
Telegraph “perfected” by Samuel Morse in 1836.
Telegraphs use Morse Code, a series of dots and dashes that make up the alphabet
Dots and dashes were sent over electrical wire
...where it would be recorded by another telegraph…thus receiving the message
First message transmitted using a Morse code telegraph, “What hath God wrought.”

Telegraph Key
Sent out the message
Telegraph receiver– received messages
Ex. 1
Ex 2.
Telegraphs eventually put
the Pony Express out of business
Rider on horse = a few days to weeks
Telegraph = a few minutes
The Telephone
In 1876, Alexander Graham Bell received/stole a patent for transmitting the human voice over electrical wires for the 1st time
Telephones quickly moved into homes, but had one drawback
Most of these telephones were wired in a "party line" configuration, which means that, especially in rural areas, anyone in your neighborhood could listen to your phone conversations.
All the phones on the party line rang at one time, no matter who the call was for. Each home had its own ring pattern. Two short rings followed by two long rings might be for the Smith home, while three short rings and one long one might be for the Jones' family
No buttons, dials or numbers; calls had to be placed through an operator at a switchboard
The operator would say, “Number, please” and a cord was plugged into a jack connecting two lines and the operator would push a button to ring the phone. Before leaving the line, the operator would wait until someone picked up or inform you that there was no answer
While other people could hear your telephone conversations,
it and telegraphs were considered “POINT
TO POINT” communication
; what was need was a way to
communicate to a MASS audience, or MASS COMMUNICATION
Heinrich Hertz, in 1887, demonstrated that electromagnetic waves could be transmitted through the air.
An Irish-Italian inventor Guglielmo Marconi is commonly credited for inventing radio in 1895
His first basic radio system was merely a telegraph that didn’t need wires to send the message
only operated at short distances
originally called "the wireless"...not radio
Marconi introduced antennas to increase the distance radio waves could travel
Founded the Marconi Wireless Telegraph Company
Marketed to marine industry, “ship to shore” and “ship to ship” communication was born
Radio Sound
Until 1906, all radio signals were in Morse code.
In 1906, Lee De Forest invented the audion tube, a vacuum tube that amplified signals, making it able to transmit sound

Radio Sound
Dec 24th, 1906: Reginald Fessenden transmitted the first radio program: the song “O Holy Night” on a violin and a bible scripture recited by a human voice. Heard only by ships out at sea
April, 1912: The Titanic sank, and only around 800 people were saved; all those saved were because of an SOS radio transmission from the ship helped bring rescue ships
The Titanic disaster made radio a household name.
1st Radio Station
Until 1920, most radios were only on ships or were used for government or telegraph use
With the invention of the audion tube, entertainment became a possibility
In 1920, Frank Conrad started the first commercially licensed radio station, 8XK (later KDKA) in Pittsburgh, playing phonograph records into a microphone
Conrad worked at Westinghouse Electric Company, and the company saw it could sell radios and spent money to expand his radio station into KDKA.
KDKA is still on the air today: AM 1020 Pittsburgh
Full transcript