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%20II-10%20Satellites.jpg

• “Satellite over Earth”. June 3, 2008. http://www.boeing.com/defense-space/space/bss/factsheets/702/xmsatradio/xmsatradio_hirez.jpeg

• “Pixel”. June 4, 2008. http://www.viewsoniceurope.com/data/62/Pixel_Subpixel_Table.jpg