Exam II Study Guide
Exam II Study Guide Com 2400
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This 11 page Study Guide was uploaded by Rio Frohriep on Saturday November 7, 2015. The Study Guide belongs to Com 2400 at Western Michigan University taught by Kayany in Summer 2015. Since its upload, it has received 282 views. For similar materials see Intro to Media and Telecom in Communication Studies at Western Michigan University.
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Date Created: 11/07/15
Comm 2400 Intro to Media and Telecommunications Exam II Study Guide Television Selenium (SE)-When light passes through this element, it changes to an equivalent electric current. This is how the ﬁrst television sets were made. Joseph May: The man to ﬁrst discover this phenomenon How a Television Camera Captures and Image The camera lens captures the image in front of it and transmits it onto the screen behind it. This image is scanned line by line Each point of light on the line passes through a selenium cell, creating a proportionate electric charge. This electric charge is then transmitted through the air like in radio. The more lines scanned, the better the quality of the image. Mechanical Television Paul Nipkow invented a mechanical scanner that used a rotating metal desk to record the image. John Baird in the UK, Charles Jenkins in the US, established mechanical television systems. The scan occurs 24/second in order to simulate movement. The image is recreated on the screen on the receiving end. Camera-to-Set Relations The television cameras and sets have to be in perfect sync—If the camera captures an image with 200 lines at 20 scans/second the TV set must also be set to recreate the image at the same speed. If it is not, the set will simply not work. Philo Farnsworth— First one to propose scanning the image with an electron beam instead of Selenium. His device was called the Electronic Scanner or an Image Dissector VK Zworykin’s Iconoscope David Sarnoff hired VK Zworykin to develop the television. Zworykin developed the Iconoscope Iconoscope: The Iconoscope was the ﬁrst practical video camera tube to be used in early television cameras. The iconoscope produced a much stronger signal than earlier mechanical designs, and could be used under any well-lit conditions. (deﬁnition from Wikipedia) Electronic television had a much better image. RCA debuted its TV during the World’s Fair in 1939. FCC allocated a band of frequencies for TV—dubbed VHF (Very High Frequency) After WWII, the ‘TV Gold Rush began. 100 stations were on the air by 1950. All the allotted frequencies were used up very quickly and in 1948, the FCC put a freeze on all Television license applications. First Television Frequencies VHF (Very High Frequencies) is the name for radio frequencies from 30MHz— 300MHz TV Channels 2-13 UHF (Ultra High Frequencies) is the name for radio frequencies from 300MHZ— 3GHz TV Channels 14-64 FCC’s 6’th report and order in 1952 FCC allocated new frequencies for TV to meet the demand (UHF) Also Established the national standard National Television Standard All Television Sets in the country must broadcast at one standard NTSC National Television Systems Committee An industry-wide committee of engineers that FCC established to make recommendations on standards NTSC recommended a 525 lines at 30 frames/second system which was the standard until 2008 Different Television Systems: NTSC—National Television Systems Committee 525 lines using 4.5 MHz FM audio, AM visual North America PAL—Phase Alternate Line 625 Alternate lines using 6.5 MHz FM Audio, AM visual UK and Western Europe SECAM—Sequential Couleur Meire 625 lines using 6.5 MHz AM adio, FM visual France, Russia, Eastern Europe Color Television Scanning is based on same principal of B/W television Camera scans amount of RGB and transmits them separately. CBS was the ﬁrst to develop a color system 343 lines at 20 frames/second Used Mechanical System Not compatible with existing B/W Systems—FCC rejected it RCA all electronic color system Compatible with pre-existing B/W systems FCC adopted this as the national standard in 1953 HDTV Broadband relay systems reduced TV’s dependence on electromagnetic spectrum space. It became possible now to improve picture quality because the worry of bandwidth was null ATSC: Advanced Television Systems Commitee—New group to make TV recommendations for standards Digital Signal v/s Anolog Analog signals send the radio waves through the air. Digital signals only send the measurements of the waves through the air The continuous analog signal is simply measured and converted to a binary code. That code is then transmitted and translated on the receiver end. Television Systems Out Today (not including those that are considered obsolete) HDTV Digital Signal Aspect ratio—16-9 (same as in a movie theatre) Horizontal lines range from 720-1080 Pixel elements rather than scanning lines 1280x720—1920x1080 resolution Requires 36MHz bandwidth for a full signal(6x what was required previously) Plasma TV: Phosphors are lit by superheated charged gas All the pixels can be lit at once—not line by line No cathode-ray tube—this is a very thin model. LCD—Liquid Crystal Display: Pixels are turned on/off at a speciﬁc refresh rate—most often 60th-120th of a second Constant backlight—when a pixel is turned off, it doesn’t allow the backlight to show through LED—Light Emitting Diode Same as LCD, but the backlight is replaced by LED as oppose to ﬂorescent OLED (Newest: as of 2015): No Backlight Pixels illuminate on their own WHO BOUGHT WHO? Rupert Murdoch’s News Corps and Fox Network in 1986 Disney bought ABC in 1995 Westinghouse bought CBS in 1995. Viacom bought it in 2001 General Electric bought RCA and NBC in 1985 Comcast bought NBC in 2015 CABLE TELEVISION History of alternate deliver methods for television CATV—Community Antena Television Public antenna that anyone in a community could connect to for a fee Started in Oregon and Pensilvania in 1948 By 1952, 70 cable systems were serving 1500 houses Distant Signal Import Better antennas—cable providers could pick up signals from neighboring cities In 1972, FCC established more formal Rules: Local communities, states, and the FCC were to regulate cable Cable stations MUST CARRY all of the local stations to their entirety The import of distant signals would be regulated Co-axial cable: A thick insulated copper wire used to transmit television with better quality. Cable Communications Act of 1984 One of the reasons for the growth of cable This act reduced the FCC control over cable and transferred that authority to the local community (This also meant that the FCC did not regulate the cable rates: With this freedom, cable jacked their rated very high, making many of the customers unhappy) FCC does not license cable systems Local governments are in control of the cable franchises in their jurisdiction. Cable-Only Channels No need to set aside frequencies for the channel Cable channels with specialized content Specialized broadcasting (aka Narrow-casting)—specialized content for a speciﬁc type of audience. Advertiser supported Premium Channels Subscribers pay extra for movies and other programs that were uninterrupted by commercials. Satellite distribution of signals made it possible to distribute programming to local cable franchises Super Stations Ted Turner-The ﬁrst to beam his channels up to a satellite for free. (His channels name was WTBS) Addressability and Pay Service Addressability—The technological feature of cable systems that allows cable systems to target programs to any television set connected to the cable system Pay Per View: a type of pay television service by which a subscriber of a television service provider can purchase events to view via private telecast. (usually sporting events) Video on Demand: are systems which allow users to select and watch/ listen to video or audio content when they choose to, rather than having to watch at a speciﬁc broadcast time. Public Access Channels Cable systems must provide equipment and time to those who wish to produce local programs on a ﬁrst come-ﬁrst serve basis Consumer protection act of 1992 FCC re-regulation of cable rates Re-transmission consent Adjusted the Must-carry rule: If the cable company and the broadcaster cannot agree on a price for the cable company to carry the broadcaster’s programing, the broadcaster can request that the cable company cut their channel from their line-up. After which, the cable company can remove that channel from their list and don’t have to cary it—even if it is a local station. Vertical Integration—A handful of corporations own companies that produce, distribute, and exhibit every form of media. Disney News Corp Time Warner CBS/Viacom Cable competitors Other technologies that compete with cable TVRO—Television Receive Only Found in Rural areas w/o cable “Backyard dish” picks up signals directly from the air and satellites Private cable SMATV—Satellite Master Antenna Television A Private network set up for places like apts, schools hospitals etc.— places that require a lot of private connections. It allows the place to provide its own cable and programming to the consumers Wireless Cable MMDS—Multichannel Multipoint Distribution Service The Assembled cable signal is broadcast to the outlaying areas using microwave technology DBS—Direct Broadcast Satellite The assembled signal is beamed to the receiver dish via satellite 28% of the population subscribe to this service Direct TV, Dish Network Now provide internet service to rural areas INTERNET Internet—essentially just Computer-to-Computer communication ARPANET—Advanced Research Projects Agency of the Dept. of Defense. First Company to create a network between computers around the country Decentralized network of Universities and Government Research Agencies Early Arpanet In 1971, 23 computers were connected to the network In 1980, the number had grown to 213 Technologies that made Computer Communication Possible Packet Switching—A method of sending and receiving messages in small packets Each packet has an address and is shet individually across the net and may follow different routs to its destination Communication Protocol TCP/IP—Transmission Control Protocol/Internet Protocol The set of rules that all computers in the network follow Developed by AT&T and Bell Labs By 1985, ARPA realized that the primary use of its network was not defense related research. So they split the network into two separate networks: One for military work, one for civilian work ARPA handed the civilian network to the National Science Foundation ISP—Internet Service Providers A local physical connection provider who serves as the customer’s local gateway to the internet. Back Bone Providers Backbone of the network is the broadband connection that sustains the long distance net working. Privatization of the internet backbone By mid 1990’s, NSF realized that the majority of business on the internet was not education related In 1995, NSF handed over the network backbone to private providers that already had a hand in the telecomm industry Network Access Points The seamless interconnection between networks to form gateways or Network Access Points (NAP) that allow smooth exchange. World Wide Web Clicking the mouse generates the commands required to perform an action Vancouver Bush —proposed the idea of developing a system of inter connected modules of knowledge Hypertext-interlinked knowledge system Ted Nelson was the ﬁrst to coin the term Tim Berners-Lee—Developed the core technology for the World Wide Web Developed HTTP protocol and HTML HTML—the coding scheme for webpages Tim Berners-Lee developed this system and distributed it for free. Grad students at UICU developed the ﬁrst program to view HTML documents—It was called Mosaic Marc Anderson—Leader of the grad students that developed Mosaic. Later developed Netscape: the ﬁrst commercial browser Bill Gates—Developed the Microsoft Internet Explorer Web v/s Internet: are they the same thing: NO!!! The World Wide Web is the hyper-linked network of the internet: it is a subset. Modem: Providing remote internet access The name comes from two words: Mod—modulation Dem—Demodulation Modems convert the digital signal from the computer to an analog signal that the telephone network could carry then later converts it back on the receiving end Modem Speeds limit the ﬂow of information Technologies that increase bandwidth DSL—Digital Subscriber Line Broadband service created by telephone companies Cable Modem Circuit developed by cable companies Hybrid Fiber optic/coaxial cable (HFC) Networks are used to relay data to and from users Google Fiber Currently offering service to Stanford, Kansas City, and Austin Cell Phones Point-to-point communication using radio waves—Two way radios It was difﬁcult to ﬁnd unique frequencies for each user, thus, cell phones didn’t take off for a while Mobile phones have been around since the 1950’s, but they were reserved for emergency services only Cell System A cell is a small area of 10 square miles with a low power transmitter Frequencies can be re-used in nonadjacent cells When Mobile phones started using this system, the name changed to Cell Phone Mobile Telephone Switching Ofﬁce The only wireless part of a cell phone is from the unit to the cell tower, from there it travels by wire to the switching ofﬁce where it then gets transmitted to wherever it needs to go. MTSO—Mobile Telephone Switching ofﬁce Cell Phone Generations 1G One frequency per conversation. Analog System Uses Bandwidth between 824-894 MHz 2G One channel can be used for several conversations Digital System Two systems—GSM, CDMA 3G More conversations per channel Digital System Smaller cells 4G Faster Data Rates LTE is a technology that allows cell providers to provide 4G speeds. GSM v/s CDMA CDMA—uses code division multiplexing (Verizon/Sprint) GSM—Uses time division multiplexing (AT&T/T-Mobile) Used by 80% of phone systems On GSM Systems, you can change the SIM cards (Subscriber Identity Module) And use it with any other GSM device Cell Phone Regulations Wireless Local Number Portability (WLNP) From 2003, FCC allowed subscribers to keep their cell phone numbers if they change service providers Cell Phone Consumer Empowerment act Would prohibit SIM locking DIED ON FLOOR AND NEVER BECAME LAW Unlocking Consumer Choice and Wireless Competition Act 2014 Unlocking of cell phones is now legal Smart Phones IBM Simon Introduced in 1992 Included a calendar, address book, fax modem, calculator, notepad, email application, and simple games Touch screen $900 Black Berry 850 1999, Research in Motion (RIM) introduced Black berry) Android 2003, Andy Rubin, Rich Miner, Nick Sears, and Chris White founded Android In 2005, Google bought the tech First Android phone G1 or HTC device was released in 2007. iPhone Released in 2007 by Apple Tablets The ﬁrst Tablet PC was introduced in 2000 by Microsoft Was intended as a computer substitute Required a stylus $2000 Apple released iPad in 2010 Apple marketed it as a consumer product and a compliment to a computer Voice Over Internet Phone (VOIP) Delivers voice communications over networks like the internet that uses packet- switching (e.g. Vonage,Skype, etc) Advantages of VOIP Transmit more than one telephone call over the same broadband connection Easily encrypt calls Location independence Integration with other services available over the internet including video conversation, messaging, and data ﬁle exchange. Disadvantages of VOIP Quality of service is unpredictable IP network doesn't have it’s own power system as regular phones do Emergency calls cannot be routed to the nearest emergency center Waves and Frequencies Waves used for radio waves are determined by: The unique features of the wave and particulate frequency range The need for spectrum space in other applications National agencies (FCC) and international agencies (ITU) determine these two things Modulation—the process of stamping information on electromagnetic waves There are two ways of modulation a carrier wave—Amplitude and Frequency Bandwidth AM signal requires 10 KHz of space FM signal require 200 KHz of space (=20 AM stations) Television requires 6 MHz of space (=30 FM stations/600 AM stations) VHF v/s UHF VHF—Very High Frequency 54 MHz-216 MHz Channels 2-13 UHF—Ultra High Frequency 470 MHz-870 MHz Channels 14-83 Long Distance Relay of Signals Direct Waves/Space Waves— Directly from transmitter to antenna Ground Waves/Surface Waves—Through the ground along the curvature of the earth Sky Waves—Bounces off the ionosphere This is known as shortwave broadcasting Microwave relays— Relay towers pick up incoming signals Amplify them Then Transmit them to the next tower Satellites Low Orbiting Medium orbiting Geo-Stationary—Used for Communication Geo-Stationary Satellites Placed in a position where the gravity is almost nonexistent so it does not fall to the ground They orbit the earth at the exact same speed the earth spins so they appear stationary Also called Geo synchronous satellites First communication satellite Developed by AT&T Launched by NASA in 1962 Named Telstar Footprint of a satellite—The range of a satellite signal Uplink and Downlink Satellites require two different frequencies so the signals don’t interfere with each other The signal beamed up to the satellite is called the Uplink The signal beamed down from the satellite is called the Downlink Transponders Receive, amplify, and change the frequency from the uplink and transmit it back to Earth A typical satellite has 24-48 transponders Satellite Frequency Satellites operate in SHF (Super High Frequency)—a range that is measured in GHz C-Band—6/4 GHz Ku-Band—14/11 GHz Ka-Band—30/20 GHz International Telecommunications Union Apart of the United Nations Assigns speciﬁc slots in geostationary orbit and frequency Coaxial Cable Bandwidth typically up to 400 MHz Fiber-optics Strands of glass through with bits of laser beams are sent Bandwidth up to 2 GHz Immune to external interference Secure—Almost impossible to tap into
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