RADIO

HAREEM FATIMA

MODERN DEVELOPMENT AND TECHNOLOGYCOURSE NUMBER 632

MADAM DR.RIZWANA FASEEL(H.O.D)

Hearing Signals Out of Thin Air

Hearing Signals Out of Thin Air

SOME ONE IS ENTERTAINING BY VOICE AND

FEELINGS

SOME ONE IS ENTERTAINING BY VOICE AND

FEELINGS

The Radio Timeline Project Page

The advance of Science and Technology depends on individuals with a curiosity who strive to build on the work of others...NO ONE INDIVIDUAL INVENTOR INVENTED THE RADIO !

List of Inventors / Scientists you may be asked to research includes1. Hans (Christian) Oersted (compass experiment - current makes magnetic field) 2. Michael Faraday (magnetic induction - moving magnet/coil makes current) 3. James Clerk Maxwell (equations describing Electromagnetic [EM] waves) 4. Thomas Edison (harmonic emission leads to design of vacuum tube) 5. Heinrich Hertz ('spark' EM wave transmission experiment) 6. Nikola Tesla (awarded radio transmission radio patent posthumously) 7. Guglielmo Marconi (famous for many radio transmission experiments) 8. John Ambrose Fleming (improved vacuum tube - diode) 9. Reginald (Aubrey) Fessenden (first AM radio broadcast) 10. Edward Armstrong (wide-band FM radio)

Radio From TelegraphRadio From Telegraph

• Radio has its roots in the Telegraph.

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

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

1876

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

Telephone

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

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

Radio Broadcasting

In 1883, a dentist named Mahlon In 1883, a dentist named Mahlon Loomis received the patent for Loomis received the patent for wireless telegraphy, butwireless telegraphy, butGuglielmo Marconi is commonly Guglielmo Marconi is commonly credited as inventing radio in 1895 credited as inventing radio in 1895 even though there is credible even though there is credible evidence that other inventors were evidence that other inventors were first.first.

Radio Broadcasting

Once Marconi patented his Once Marconi patented his invention in England, his invention in England, his next step was to sell it to next step was to sell it to the marine industry. the marine industry. Soon, the majority of Soon, the majority of oceangoing ships were all oceangoing ships were all equipped with his equipped with his equipment - which made equipment - which made Marconi a very rich man.Marconi a very rich man.

1898

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

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

FIRST RADIO IN HOME

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

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

IMPACT ON SOCIETY

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

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

DEVELOPMENTS IN RADIO

Antennas

RADIO WAVES CATCHING IN AIR

11 22 33

AM AND FM

RADIO CONSIST OF TWO KINDS OF FREQUENCIES

AM AND FM

AM RADIO:

It stands for

amplitude

modulation

FM RADIO:

It stands for

frequency

modulation.

TODAY IS FM

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

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

TODAY RADIO STATIONSTODAY RADIO STATIONS

QUESTIONS?

THANK YOU…!