Compmed Satellite Fiber Optics And Microwave

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Compmed Satellite Fiber Optics And Microwave

  1. 1. Satellite, Fiber Optics and Microwave Psilomelane Dacuno Adrian Lapiz
  2. 2. Satellite <ul><li>a satellite is any object which has been placed into orbit by human endeavor. </li></ul><ul><li>They are sometimes called artificial satellites to distinguish them from natural satellites such as the Moon. </li></ul>
  3. 3. Early theoretical work on artificial satellites <ul><li>The first known fictional depiction of a satellite being launched into orbit is a short story by Edward Everett Hale, The Brick Moon . </li></ul><ul><li>Konstantin Tsiolkovsky (1857–1935) published ( The Exploration of Cosmic Space by Means of Reaction Devices ), which is the first academic treatise on the use of rocketry to launch spacecraft. </li></ul>
  4. 4. <ul><li>Konstantin Tsiolkovsky calculated the orbital speed required for a minimal orbit around the Earth at 8 km/second, and that a multi-stage rocket fueled by liquid propellants could be used to achieve this. </li></ul><ul><li>In 1928 Herman Potočnik (1898–1929) published his sole book, The Problem of Space Travel - The Rocket Motor, a plan for a breakthrough into space and a permanent human presence there. </li></ul>
  5. 5. <ul><li>In 1945 the English science fiction writer Arthur C. Clarke (b. 1917) conceived of the possibility for mass artificial communication satellites in his Wireless World article. </li></ul><ul><li>Clarke examined the logistics of satellite launch, possible orbits and other aspects of the creation of a network of world-circling satellites, pointing to the benefits of high-speed global communications. </li></ul><ul><li>He also suggested that three geostationary satellites would provide coverage over the entire planet. </li></ul>
  6. 6. History <ul><li>The first artificial satellite was Sputnik 1, launched by the Soviet Union on 4 October 1957. This triggered the Space Race between the Soviet Union and the United States. </li></ul><ul><li>On July 29, 1955, the White House announced that the U.S. intended to launch satellites by the spring of 1958. This became known as Project Vanguard. On July 31, the Soviets announced that they intended to launch a satellite by the fall of 1957. </li></ul><ul><li>The largest artificial satellite currently orbiting the Earth is the International Space Station </li></ul>
  7. 7. Communication Satellites or COMSAT <ul><li>Telecommunication satellite is a kind of satellite that’s very close to our daily life </li></ul><ul><li>are satellites stationed in space for the purpose of telecommunications. Modern communications satellites typically use geosynchronous orbits, Molniya orbits or Low Earth orbits. </li></ul><ul><li>There are many more types of satellites like Weather, Biosatellites, Space Stations and etc. </li></ul>
  8. 8. <ul><li>The first and historically the most important application for communication satellites is in international telephony. </li></ul>Telephony
  9. 9. <ul><li>Fixed-point telephones relay calls to an earth station, where they are then transmitted to a geostationary satellite. </li></ul><ul><li>An analogous path is then followed on the downlink. In contrast, mobile telephones (to and from ships and airplanes) must be directly connected to equipment to uplink the signal to the satellite, as well as being able to ensure satellite pointing in the presence of disturbances, such as waves onboard a ship. </li></ul>
  10. 10. Satellite Television and radio <ul><li>There are two satellite types used for North American television and radio: </li></ul><ul><li>Direct Broadcast Satellite (DBS) </li></ul><ul><li>Fixed Service Satellite (FSS) </li></ul><ul><li>DBS – used for satellite TV services </li></ul><ul><li>FSS – used for distance learning by schools and universities, business television (BTV), video-conferencing, and general commercial telecommunications </li></ul>
  11. 11. <ul><li>In recent years, satellite communication technology has been used as a means to connect to the Internet via broadband data connections. This can be very useful for users who are located in very remote areas, and cannot access a wireline broadband or dialup connection. </li></ul>
  12. 12. Microwave <ul><li>Microwaves are electromagnetic waves with wavelengths longer than those of terahertz (THz) frequencies, but relatively short for radio waves. </li></ul><ul><li>Microwaves have wavelengths approximately in the range of 30 cm (frequency = 1 GHz) to 1 mm (300 GHz). </li></ul>
  13. 13. <ul><li>The existence of electromagnetic waves, of which microwaves are part of the frequency spectrum, was predicted by James Clerk Maxwell in 1864 from his equations. </li></ul><ul><li>In 1888, Heinrich Hertz was the first to demonstrate the existence of electromagnetic waves by building an apparatus that produced and detected microwaves </li></ul>
  14. 14. <ul><li>The microwave range includes ultra-high frequency (UHF) (0.3–3 GHz), super high frequency (SHF) (3–30 GHz), and extremely high frequency (EHF) (30–300 GHz) signals. </li></ul>
  15. 15. Uses <ul><li>A microwave oven works by passing microwave radiation, usually at a frequency of 2450 MHz (a wavelength of 12.24 cm), through the food. Water, fat, and sugar molecules in the food absorb energy from the microwave beam in a process called dielectric heating. </li></ul><ul><li>A common misconception is that microwave ovens cook food from the &quot;inside out&quot;. In reality, microwaves are absorbed in the outer layers of food in a manner somewhat similar to heat from other methods. </li></ul>
  16. 16. <ul><li>Microwave radio is used in broadcasting and telecommunication transmissions because, due to their short wavelength, highly directive antennas are smaller and therefore more practical than they would be at longer wavelengths (lower frequencies). </li></ul><ul><li>There is also more bandwidth in the microwave spectrum than in the rest of the radio spectrum; the usable bandwidth below 300 MHz is less than 300 MHz while many GHz can be used above 300 MHz. </li></ul><ul><li>Typically, microwaves are used in television news to transmit a signal from a remote location to a television station from a specially equipped van. </li></ul>
  17. 17. <ul><li>Before the advent of fiber optic transmission, most long distance telephone calls were carried via microwave point-to-point links through sites </li></ul><ul><li>Radar also uses microwave radiation to detect the range, speed, and other characteristics of remote objects. </li></ul><ul><li>Wireless LAN protocols, such as Bluetooth and the IEEE 802.11 specifications, also use microwaves </li></ul><ul><li>Some mobile phone networks, like GSM, also use the lower microwave frequencies. </li></ul><ul><li>Most radio astronomy uses microwaves. </li></ul>
  18. 18. Optical Fiber <ul><li>An optical fiber (or fibre ) is a glass or plastic fiber designed to guide light along its length by confining as much light as possible in a propagating form. </li></ul>
  19. 19. <ul><li>The light-guiding principle behind optical fibers was first demonstrated in by Daniel Collodon and Jaques Babinet in the 1840s, with Irish inventor John Tyndall offering public displays using water-fountains ten years later. </li></ul><ul><li>Optical fiber can be used as a medium for telecommunication and networking because it is flexible and can be bundled as cables. </li></ul><ul><li>It is especially advantageous for long-distance communications, because light propagates through the fiber with little attenuation compared to electrical cables. </li></ul><ul><li>Although fibers can be made out of transparent plastic, glass, or a combination of the two, the fibers used in long-distance telecommunications applications are always glass, because of the lower optical attenuation. </li></ul>
  20. 20. <ul><li>The most commonly-used optical transmitters are semiconductor devices such as light-emitting diodes (LEDs) and laser diodes. The difference between LEDs and laser diodes is that LEDs produce incoherent light, while laser diodes produce coherent light. </li></ul>

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