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Radio commuincation
 

Radio commuincation

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    Radio commuincation Radio commuincation Presentation Transcript

    • Radio Broadcasting
      • 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.
    • Radio Broadcasting
      • In 1876, Alexander Graham Bell transmitted the human voice over wires for the first time.
      • Soon, his invention moved from the lab to the home and life hasn't been the same since.
    • Radio Broadcasting
      • 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 1887, Heinrich Hertz demonstrated that electromagnetic waves could be transmitted through the air.
      • As a result, the term "Hertz" is now used to specify cycles per second for the frequency of both sound and radio waves.
    • Radio Broadcasting
      • In 1883, a dentist named Mahlon Loomis received the patent for wireless telegraphy, but
      • Guglielmo Marconi is commonly credited as inventing radio in 1895 even though there is credible evidence that other inventors were first.
    • Radio Broadcasting
      • 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).
    • Radio Broadcasting
      • Once Marconi patented his invention in England, his next step was to sell it to the marine industry.
      • Soon, the majority of oceangoing ships were all equipped with his equipment - which made Marconi a very rich man.
    • Radio Broadcasting
      • Ship radio operators who had never heard anything but Morse code received the first radio broadcast from Boston in 1906.
      • It must have seemed like the Twilight Zone at sea when the ships heard Christmas carols coming from their radios!
    • Radio Broadcasting
      • In 1912, a tragedy happened that shook the World. The "unsinkable" luxury liner, the Titanic, hit an iceberg and sank.
      • The tragedy could have been worse. Thanks to the new invention of radio, about 800 people were saved.
    • Radio Broadcasting
      • In the early days of radio there was no way to record sound - everything was performed "live."
      • Although the first sound recording device can be traced back to 1855, it was some time before the concept was applied to radio.
    • Radio Broadcasting
      • 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.
    • Radio Broadcasting
      • 8XK (now KDKA) in Pittsburgh, Pennsylvania is widely credited as the first radio station in the US, but the truth is that
      • other stations preceded 8XK, but Frank Conrad did start the first daily program on that station.
    • Radio Broadcasting
      • Conrad initially played music by holding a mic up to a phonograph.
      • In no time, people were tuning in, and Conrad became a mini-celebrity.
      • Westinghouse, who owned the station, took notice and expanded Conrad's operations.
    • Radio Broadcasting
      • 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.
    • Radio Broadcasting
      • The popularity of the new medium enticed people to build their own personal radio stations.
      • Soon there were too many stations for the number of frequencies available on the radio dial.
    • Radio Broadcasting
      • In 1922, another element entered the picture — broadcast advertising.
      • What was originally referred to as a “toll broadcast” is now known as a commercial.
      • Along with the advent of ads came sponsors and the need for regulation.
    • Radio Broadcasting
      • 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.
    • Radio Broadcasting
      • Call letters for stations east of the Mississippi start with a "W", and stations west of the Mississippi start with "K."
      • A few stations were licensed before this rule was put in to effect, so there are couple of exceptions.
    • Radio Broadcasting
      • In 1934, the FRC was reorganized into Federal Communications Commission or the FCC.
      • The FCC's regulatory powers were expanded to include telephone and telegraph - and some years later, television.
    • Radio Broadcasting
      • The FCC reserved some nonprofit frequencies for educational and religious groups.
      • Due to the big-business bias of the government, these frequencies were the least desirable and were limited in power.
    • Radio Broadcasting
      • AM stands for amplitude modulation, and ranges from 535 to 1705kHz.
      • Kilohertz are thousands of cycles per-second of electromagnetic energy.
      • These are the numbers you see on your AM radio dial.
    • Radio Broadcasting
      • The tan area at the left are AM radio waves and are at a lower frequency than FM radio or TV
      • Stations can be placed every 10kHz along the AM band so there are 117 channels available.
    • Radio Broadcasting
      • The signals of most AM stations are limited in their range, so the same frequencies can be used many times as long as they are separated.
      • This is how we can have nearly 5,000 AM radio stations in the US on 117 different frequencies.
    • Radio Broadcasting
      • Modulation refers to how sound is encoded on a radio wave (called a carrier wave) so that the sound can be detected by a radio receiver.
      • The top drawing is not modulated by any sound so there would be silence on your radio.
    • Radio Broadcasting
      • 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).
    • Radio Broadcasting
      • FM stations must be 200kHz apart which means that there's room for 200 FM stations on the FM band.
      • FM stations don't have nice round numbers like 820 or 1240. Instead, an FM station may be at 88.7 on the dial.
    • Radio Broadcasting
      • FM and TV signals travel in a straight line and don't bend around the earth as AM waves do.
      • The farther away from the FM or TV station you are, the higher you have to have an antenna to receive the signal.
    • Radio Broadcasting
      • Frequency relates to the pitch of a sound - how high or low it is. A 20 Hz frequency sound is extremely low-pitched - almost a rumble.
      • A 20,000 Hz sound is the highest pitched sound that can be imagined.
    • Radio Broadcasting
      • A person with very good hearing will be able to hear sounds from 20-20,000 Hz.
      • The common range used for FM radio and TV is from 50 to 15,000 Hz. and AM radio is below this range.
    • Radio Broadcasting
      • The average US resident listens to 22 hours of Radio per week
      • In the US, Radios out-number people 3 to 1
      • In most countries, Radio continues to be the primary source of news and information