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Radio Communication

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This presentation was designed for a high school communications skills class - it gives the basics and history of radio communications

Radio Communication

  1. 1. Radio Broadcasting <ul><li>Radio has its roots in the Telegraph. </li></ul><ul><li>This device was the first widely-used form of long-distance communication. </li></ul><ul><li>In 1836, Samuel Morse invented a language of dots and dashes that is still used today. </li></ul>
  2. 2. Radio Broadcasting <ul><li>In 1876, Alexander Graham Bell transmitted the human voice over wires for the first time. </li></ul><ul><li>Soon, his invention moved from the lab to the home and life hasn't been the same since. </li></ul>
  3. 3. Radio Broadcasting <ul><li>Most of these telephones were wired on party lines, which means that many of your neighbors could listen to your calls. </li></ul><ul><li>All the phones on the party line rang at one time, and each home had its own ring pattern. </li></ul>
  4. 4. Radio Broadcasting <ul><li>In 1887, Heinrich Hertz demonstrated that electromagnetic waves could be transmitted through the air. </li></ul><ul><li>As a result, the term &quot;Hertz&quot; is now used to specify cycles per second for the frequency of both sound and radio waves. </li></ul>
  5. 5. Radio Broadcasting <ul><li>In 1883, a dentist named Mahlon Loomis received the patent for wireless telegraphy, but </li></ul><ul><li>Guglielmo Marconi is commonly credited as inventing radio in 1895 even though there is credible evidence that other inventors were first. </li></ul>
  6. 6. Radio Broadcasting <ul><li>Nikola Tesla demonstrated wireless transmissions during a lecture on the potential of high frequency transmitting in 1891. </li></ul><ul><li>In 1893, after continued research, Tesla presented a paper on the basics of radio (wireless telegraph). </li></ul>
  7. 7. Radio Broadcasting <ul><li>Once Marconi patented his invention in England, his next step was to sell it to the marine industry. </li></ul><ul><li>Soon, the majority of oceangoing ships were all equipped with his equipment - which made Marconi a very rich man. </li></ul>
  8. 8. Radio Broadcasting <ul><li>Ship radio operators who had never heard anything but Morse code received the first radio broadcast from Boston in 1906. </li></ul><ul><li>It must have seemed like the Twilight Zone at sea when the ships heard Christmas carols coming from their radios! </li></ul>
  9. 9. Radio Broadcasting <ul><li>In 1912, a tragedy happened that shook the World. The &quot;unsinkable&quot; luxury liner, the Titanic, hit an iceberg and sank. </li></ul><ul><li>The tragedy could have been worse. Thanks to the new invention of radio, about 800 people were saved. </li></ul>
  10. 10. Radio Broadcasting <ul><li>In the early days of radio there was no way to record sound - everything was performed &quot;live.&quot; </li></ul><ul><li>Although the first sound recording device can be traced back to 1855, it was some time before the concept was applied to radio. </li></ul>
  11. 11. Radio Broadcasting <ul><li>In 1898, Danish inventor Valdemar Poulsen created the Telegraphone, the first practical magnetic sound recorder using a piano wire as the recording medium. </li></ul><ul><li>Soon, wire recorders begin to appear on the American market. </li></ul>
  12. 12. Radio Broadcasting <ul><li>8XK (now KDKA) in Pittsburgh, Pennsylvania is widely credited as the first radio station in the US, but the truth is that </li></ul><ul><li>other stations preceded 8XK, but Frank Conrad did start the first daily program on that station. </li></ul>
  13. 13. Radio Broadcasting <ul><li>Conrad initially played music by holding a mic up to a phonograph. </li></ul><ul><li>In no time, people were tuning in, and Conrad became a mini-celebrity. </li></ul><ul><li>Westinghouse, who owned the station, took notice and expanded Conrad's operations. </li></ul>
  14. 14. Radio Broadcasting <ul><li>Once radio broadcasting was launched, people began to realize just how significant this new medium could be. </li></ul><ul><li>For example, KDKA, broadcast the 1920 Harding-Cox presidential election returns well in advance of the papers. </li></ul>
  15. 15. Radio Broadcasting <ul><li>The popularity of the new medium enticed people to build their own personal radio stations. </li></ul><ul><li>Soon there were too many stations for the number of frequencies available on the radio dial. </li></ul>
  16. 16. Radio Broadcasting <ul><li>In 1922, another element entered the picture — broadcast advertising. </li></ul><ul><li>What was originally referred to as a “toll broadcast” is now known as a commercial. </li></ul><ul><li>Along with the advent of ads came sponsors and the need for regulation. </li></ul>
  17. 17. Radio Broadcasting <ul><li>The Congress passed the Radio Act of 1927, which created the Federal Radio Commission - FRC. </li></ul><ul><li>Its purpose was to oversee the licensing of transmitters, assigning radio frequencies, call letters, and power limits. </li></ul>
  18. 18. Radio Broadcasting <ul><li>Call letters for stations east of the Mississippi start with a &quot;W&quot;, and stations west of the Mississippi start with &quot;K.&quot; </li></ul><ul><li>A few stations were licensed before this rule was put in to effect, so there are couple of exceptions. </li></ul>
  19. 19. Radio Broadcasting <ul><li>In 1934, the FRC was reorganized into Federal Communications Commission or the FCC. </li></ul><ul><li>The FCC's regulatory powers were expanded to include telephone and telegraph - and some years later, television. </li></ul>
  20. 20. Radio Broadcasting <ul><li>The FCC reserved some nonprofit frequencies for educational and religious groups. </li></ul><ul><li>Due to the big-business bias of the government, these frequencies were the least desirable and were limited in power. </li></ul>
  21. 21. Radio Broadcasting <ul><li>AM stands for amplitude modulation, and ranges from 535 to 1705kHz. </li></ul><ul><li>Kilohertz are thousands of cycles per-second of electromagnetic energy. </li></ul><ul><li>These are the numbers you see on your AM radio dial. </li></ul>
  22. 22. Radio Broadcasting <ul><li>The tan area at the left are AM radio waves and are at a lower frequency than FM radio or TV </li></ul><ul><li>Stations can be placed every 10kHz along the AM band so there are 117 channels available. </li></ul>
  23. 23. Radio Broadcasting <ul><li>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. </li></ul><ul><li>This is how we can have nearly 5,000 AM radio stations in the US on 117 different frequencies. </li></ul>
  24. 24. Radio Broadcasting <ul><li>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. </li></ul><ul><li>The top drawing is not modulated by any sound so there would be silence on your radio. </li></ul>
  25. 25. Radio Broadcasting <ul><li>FM or frequency modulated radio and TV waves act differently than AM radio waves. </li></ul><ul><li>The FM radio band goes from 88 to 108 MHz (megahertz, or millions of cycles per second). </li></ul>
  26. 26. Radio Broadcasting <ul><li>FM stations must be 200kHz apart which means that there's room for 200 FM stations on the FM band. </li></ul><ul><li>FM stations don't have nice round numbers like 820 or 1240. Instead, an FM station may be at 88.7 on the dial. </li></ul>
  27. 27. Radio Broadcasting <ul><li>FM and TV signals travel in a straight line and don't bend around the earth as AM waves do. </li></ul><ul><li>The farther away from the FM or TV station you are, the higher you have to have an antenna to receive the signal. </li></ul>
  28. 28. Radio Broadcasting <ul><li>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. </li></ul><ul><li>A 20,000 Hz sound is the highest pitched sound that can be imagined. </li></ul>
  29. 29. Radio Broadcasting <ul><li>A person with very good hearing will be able to hear sounds from 20-20,000 Hz. </li></ul><ul><li>The common range used for FM radio and TV is from 50 to 15,000 Hz. and AM radio is below this range. </li></ul>
  30. 30. Radio Broadcasting <ul><li>The average US resident listens to 22 hours of Radio per week </li></ul><ul><li>In the US, Radios out-number people 3 to 1 </li></ul><ul><li>In most countries, Radio continues to be the primary source of news and information </li></ul>

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