Transcript Chapter #15
Chapter #15 Communication Technology Chapter 15.1 Notes • Signal a sign that represents information, such as a command, a direction, or a warning. • Code a set of rules used to interpret signals that convey information. • Telecommunication a communication method that uses electromagnetic means. • Telephone • Internet • Radio • TV • Fiber Optics • Analog signal a signal corresponding to a quantity whose values can change continuously. • Digital signal a signal that can be represented as a sequence of discrete values. • Optical Fibers a hair-thin, transparent strand of glass or plastic that transmits signals using pulses of light. Geostationary orbit is the path of a satellite around the Earth, where the position of the satellite relative to the ground does NOT change. Chapter 15.2 Notes • Physical transmission a transmission of a signal using wires, cables, or optical fibers. • Atmospheric transmission a transmission of a signal using electromagnetic waves. • Carrier a continuous wave that can be modulated to send a signal. • Modulate to change a wave’s amplitude or frequency in order to send a signal. • Amplitude modulation (AM) radio have a frequency between 540 and 1700 kHz…can be picked up over 50 miles away. • Frequency modulation (FM) radio have a frequency between 88 and 108 MHz…can be picked up at about 25-50 miles away. • Cathode-ray tube a tube that uses an electron beam to create a display on a phosphorescent screen. (black and white TV’s) Pixel the smallest element of a display image. Chapter 15.3 Notes • Computer an electronic device that can accept data and instructions, follow the instructions, and output the results. • Random-access memory (RAM) a storage device that allows stored data to be read in the same access time. • Read-only memory (ROM) a memory device containing data that cannot be changed. • Hardware the equipment that makes up a computer system. • Software the instructions, data, and programming that make a computer system work. • Operating system the software that controls a computer’s activities. • Internet a large computer network that connects many local and smaller networks. Work Cited • • • • • • “Satellite”. June 3, 2008. http://celebrating200years.noaa.gov/breakthroughs/global_positioning_sys/ gps_satellite_650.jpg “Morse Code”. June 3, 2008. http://www.dkimages.com/discover/previews/795/940283.JPG “Fiber Optics”. June 3, 2008. http://img.alibaba.com/photo/11235913/TrueWave_RS_Nonzero_Dispersion _Optical_Fiber.jpg “Satellites around the Earth”. June 3, 2008. http://www.wmo.ch/pages/prog/www/images/GOS/Figure%20II10%20Satellites.jpg “Satellite over Earth”. June 3, 2008. http://www.boeing.com/defensespace/space/bss/factsheets/702/xmsatradio/xmsatradio_hirez.jpeg “Pixel”. June 4, 2008. http://www.viewsoniceurope.com/data/62/Pixel_ Subpixel_Table.jpg