Broadcasting, Cable, the Internet and Beyond

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Broadcasting, Cable, the Internet and Beyond

  1. 1. Broadcasting, Cable, the Internet and Beyond Chapter 3 <ul><li>Quick Facts </li></ul><ul><li>Bandwidth of an FM channel: 200 kilohertz </li></ul><ul><li>Bandwidth of a digital television channel: 6 megahertz </li></ul><ul><li>First high-definition TV broadcasts: 1998 </li></ul><ul><li>Cost of 51” digital HDTV set (1999): $5,000 </li></ul><ul><li>Cost of 51” digital HDTV set (2006): $1,699 </li></ul><ul><li>Percent of dads hoping for a consumer electronics gift on Father’s Day, 2006: 42 </li></ul>
  2. 2. Broadcasting, Cable, the Internet and Beyond Chapter 3 <ul><li>Basic Principle of Media Technology </li></ul><ul><li>Facsimile Technology - All modes of mass communication based on this process </li></ul><ul><li>Fidelity - a way to describe how faithfully a facsimile represents the original </li></ul><ul><ul><li>High Fidelity is reproduction that closely approximates the original signal </li></ul></ul><ul><li>Radio waves can be used to transmit facsimiles of pictures and sounds </li></ul>
  3. 3. Broadcasting, Cable, the Internet and Beyond Chapter 3 <ul><li>Transduction </li></ul><ul><li>Transduction - the process of changing one form of energy into another form </li></ul><ul><li>Both analog and digital broadcasting involves different kinds of transductions </li></ul><ul><li>Noise in the transmission reduces the fidelity of the signal </li></ul><ul><ul><li>Analog transmission loses fidelity at each phase of the process </li></ul></ul><ul><ul><li>Digital technology reduces lose of fidelity in the transduction process. </li></ul></ul><ul><li>Television and radio signals begin as physical energy </li></ul><ul><ul><li>Commonly referred to as light waves or sound waves </li></ul></ul><ul><ul><li>More and more broadcast signals are now in digital form </li></ul></ul>
  4. 4. Broadcasting, Cable, the Internet and Beyond Chapter 3 <ul><li>Examples of transduction </li></ul><ul><li>Capturing sound of a bird chirping using a microphone involves the transduction of sound waves into electricity </li></ul><ul><ul><li>Making a recording of the bird involves making a facsimile of the original sound </li></ul></ul><ul><li>Transmitting the sound of the chirping involves the transduction of the electrical energy into electromagnetic energy </li></ul><ul><ul><li>The audio of a bird chirping is superimposed on the carrier wave of the broadcast channel </li></ul></ul><ul><li>At home, our antenna detects the transmitted signal and begins to reverse the transduction process </li></ul>
  5. 5. Broadcasting, Cable, the Internet and Beyond Chapter 3 <ul><li>Signal and Noise </li></ul><ul><li>Signal - an electrical impulse or amount of power </li></ul><ul><li>Noise - the amount of unwanted interference </li></ul><ul><li>Signal to noise ratio - the amount of pure signal present compared to the amount of unwanted noise </li></ul><ul><li>Analog signals are subject to varying amounts of noise </li></ul><ul><ul><li>As signal goes farther away from the transmitter, more noise is added </li></ul></ul><ul><li>Digital signals are subject to less noise interference than analog signals </li></ul>
  6. 6. Broadcasting, Cable, the Internet and Beyond Chapter 3 <ul><li>Digital Transmission </li></ul><ul><li>Digital technology uses binary codes </li></ul><ul><ul><li>Binary codes use sequences of 0s and 1s - called bytes </li></ul></ul><ul><li>Today, both digital radio and television signals have been approved for broadcasting </li></ul><ul><li>Digital transmission - sending binary data to receivers capable of converting this data back into audio or video signals </li></ul><ul><ul><li>Digital television (DTV) is growing in popularity in the U.S. </li></ul></ul><ul><ul><li>Two different digital radio systems exist. One uses satellites, the other involves sending a terrestrial signal by the local broadcaster </li></ul></ul>
  7. 7. Broadcasting, Cable, the Internet and Beyond Chapter 3 <ul><li>Oscillation and the Waveform </li></ul><ul><li>Oscillation - a basic concept of audio and video signal processing </li></ul><ul><ul><li>Examples - vibration of air produced by our mouths makes </li></ul></ul><ul><ul><li>the sounds we hear and vibration of light make up all the images we see </li></ul></ul><ul><ul><li>Electromagnetic waves are subject to oscillation </li></ul></ul><ul><li>The oscillations of a radio wave defines its frequency </li></ul><ul><li>Waveform - the footprint or image of an oscillation we use to visualize the presence of the invisible </li></ul>
  8. 8. Broadcasting, Cable, the Internet and Beyond Chapter 3 <ul><li>Frequency and Amplitude </li></ul><ul><li>A radio wave may be described in terms of frequency and amplitude </li></ul><ul><li>Frequency - the number of waves that pass a given point in a given time </li></ul><ul><li>Frequency is usually measured in hertz (Hz) </li></ul><ul><li>The higher the frequency the shorter the wavelength </li></ul><ul><li>Amplitude (power) - the height or depth of the wave from its normal position </li></ul>
  9. 9. Broadcasting, Cable, the Internet and Beyond Chapter 3 <ul><li>Frequency Response </li></ul><ul><li>Frequency Response - range of frequencies that a radio set is capable of receiving </li></ul><ul><ul><li>Example : How well a radio reproduces a range of audio frequencies </li></ul></ul><ul><li>The ear can hear a frequency range of approximately 10 octaves, from a low of 20 Hz to a high of 20,000 Hz </li></ul><ul><li>CDs can reproduce the entire range of audio frequencies that the human ear can hear </li></ul>
  10. 10. Broadcasting, Cable, the Internet and Beyond Chapter 3 <ul><li>Steps in Signal Processing </li></ul><ul><li>Step One - Signal Generation </li></ul><ul><li>Mechanical methods of reproducing sound </li></ul><ul><ul><li>Microphones </li></ul></ul><ul><ul><li>Phonograph records </li></ul></ul><ul><ul><li>Tape recorders </li></ul></ul><ul><li>Digital methods of reproducing sound </li></ul><ul><ul><li>Digital Audio Tape (DAT) </li></ul></ul><ul><ul><li>Compact Discs (CDs) and Digital Versatile Disks (DVDs) </li></ul></ul><ul><ul><li>Minidiscs (MD) </li></ul></ul><ul><ul><li>Computer files (MP3s) </li></ul></ul>
  11. 11. Broadcasting, Cable, the Internet and Beyond Chapter 3 <ul><li>Video Signal Generation (NTSC) </li></ul><ul><li>Television’s ability to transmit images is based on the technology of scanning </li></ul><ul><li>Analog U.S. television scans a television picture using two fields of information for a total of 525 lines </li></ul><ul><li>Each field consists of 262 1/2 horizontal scanning lines </li></ul><ul><li>The two fields interlace to combine to form a single picture called a frame </li></ul>
  12. 12. Broadcasting, Cable, the Internet and Beyond Chapter 3 <ul><li>Video Signal Generation (Digital television DTV) (Cont.) </li></ul><ul><li>Digital television has several standards </li></ul><ul><li>High Definition Television (HDTV) represents the best picture quality </li></ul><ul><li>HDTV uses either 480, 720 or 1080 scanning lines, 480 being the lowest range, 720 medium, and 1080 being the highest </li></ul><ul><li>Digital television channels are free of noise and look better than comparable analog television </li></ul>
  13. 13. Broadcasting, Cable, the Internet and Beyond Chapter 3 <ul><li>Step 2 - Signal Amplification and Processing </li></ul><ul><li>Audio Signal Processing </li></ul><ul><ul><li>Amplifiers boost or modify electrical signals </li></ul></ul><ul><ul><li>Mixing consoles and control boards are used to input, select, control, mix, combine, route, and process signals </li></ul></ul><ul><ul><li>Today many signal processing functions can be accomplished using a computer (Desktop Audio) </li></ul></ul>
  14. 14. Broadcasting, Cable, the Internet and Beyond Chapter 3 <ul><li>Step 2 - Signal Amplification and Processing (Cont.) </li></ul><ul><li>Video Amplification and Processing </li></ul><ul><ul><li>Video signals are mixed using a switcher </li></ul></ul><ul><ul><li>Special effects generators provide keying and chromakey effects to a television picture </li></ul></ul><ul><ul><li>Digital Video Effects provide special effects that can manipulate the size and position of a picture </li></ul></ul><ul><ul><li>Computers are being used today to manipulate and edit video images (Desktop Video) </li></ul></ul>
  15. 15. Broadcasting, Cable, the Internet and Beyond Chapter 3 <ul><li>Step 3 - Signal Transmission </li></ul><ul><li>Electromagnetic Spectrum is very large </li></ul><ul><li>Radio and television signals occupy a portion of the electromagnetic spectrum </li></ul><ul><ul><li>Radio and television stations are assigned specific frequencies </li></ul></ul><ul><ul><li>Carrier wave - the signal produced by a station’s transmitter </li></ul></ul><ul><ul><ul><li>AM - The carrier wave is modulated </li></ul></ul></ul><ul><ul><ul><li>FM - The frequency is modulated </li></ul></ul></ul><ul><li>Only a small part of the electromagnetic spectrum is utilized for AM and FM broadcasting </li></ul><ul><ul><li>AM and FM radio stations use different portions of the spectrum </li></ul></ul>
  16. 16. Broadcasting, Cable, the Internet and Beyond Chapter 3 <ul><li>Radio Bands in the Electromagnetic Spectrum </li></ul><ul><li>Medium Wave Band - 107 AM channels, air and marine radio </li></ul><ul><li>High Frequency Band - International Shortwave, CB, and Ham radio </li></ul><ul><li>Very High Frequency (VHF) - FM radio, police radio, airline navigation systems, and TV channels 2 - 13 </li></ul><ul><li>Ultra High Frequency (UHF) - UHF and DTV channels 14 - 38, police and taxi mobile radio, radar and weather satellites </li></ul><ul><li>Super High Frequency (SHF) - Ku and C band satellites, Microwave transmission, air navigation </li></ul><ul><li>Extremely High Frequency (EHF) -special military communications </li></ul>
  17. 17. Broadcasting, Cable, the Internet and Beyond Chapter 3 <ul><li>Spectrum management - the process of defining and keeping track of what frequencies will be assigned and licensed for special purposes </li></ul><ul><li>The FCC decides who gets a broadcast license is </li></ul><ul><li>Radio Classifications </li></ul><ul><ul><li>AM Radio - 117 Channels assigned between 540 and 1700 Khz </li></ul></ul><ul><ul><ul><li>Each AM channel occupies 10 Hz of bandwidth </li></ul></ul></ul><ul><ul><li>FM Radio - 100 Channels assigned between 88 and 108 Mhz </li></ul></ul><ul><ul><ul><li>Each FM channel occupies 200 Khz of bandwidth </li></ul></ul></ul><ul><ul><ul><li>Commercial FM is divided into three zones covering the US </li></ul></ul></ul><ul><ul><ul><li>January 2000, new low-powered FM was created </li></ul></ul></ul><ul><ul><li>Digital Radio (HD) - approved for broadcasters to create digital services in addition to analog broadcasts. </li></ul></ul>
  18. 18. Broadcasting, Cable, the Internet and Beyond Chapter 3 <ul><li>Signal Transmission (cont.) </li></ul><ul><li>Spectrum Management -Television and satellite channels </li></ul><ul><li>Television Classifications and Basics </li></ul><ul><ul><li>Each television channel occupies 6 Mhz of bandwidth </li></ul></ul><ul><ul><ul><li>VHF television - Channels 2 - 13 </li></ul></ul></ul><ul><ul><ul><li>UHF television - Channels 14 - 83 </li></ul></ul></ul><ul><ul><ul><li>UHF channel assignments include new digital television channels (DTV) </li></ul></ul></ul><ul><ul><li>Satellite TV - Direct Broadcast Satellite (DBS) uses the Super High Frequency band (SHF) </li></ul></ul>
  19. 19. Broadcasting, Cable, the Internet and Beyond Chapter 3 <ul><li>Wired Communication </li></ul><ul><li>Cable TV uses coaxial cable as a transmission medium </li></ul><ul><li>Coaxial cable is capable of transmitting a large number of channels through the wire </li></ul><ul><ul><li>Digital compression increases channel capacity even more </li></ul></ul><ul><li>Addressability - the ability to send a program to some households but not others. </li></ul><ul><ul><li>Addressability is used for pay-per-view (PPV) TV </li></ul></ul><ul><li>Fiber Optics uses digital technology - almost unlimited bandwidth </li></ul><ul><ul><li>Fiber can carry television, telephone and broadband information </li></ul></ul>
  20. 20. Broadcasting, Cable, the Internet and Beyond Chapter 3 <ul><li>Step 4: Signal Reception - Radio </li></ul><ul><li>AM radio is ideal for car radios </li></ul><ul><ul><li>Signals travel long distances, especially at night </li></ul></ul><ul><ul><li>AM is subject to static interference and limited frequency response. Receiver quality is often poor </li></ul></ul><ul><li>FM radio is a full fidelity medium but is limited to line of sight transmission </li></ul><ul><ul><li>FM requires a long antenna </li></ul></ul><ul><ul><li>Signals tend to be blocked by buildings or moving objects </li></ul></ul><ul><ul><li>Radio Broadcast Data Systems or ‘Smart’ radios provide some functionality </li></ul></ul><ul><li>Satellite radios need a special antenna and receiver </li></ul><ul><li>Satellite services are pay services </li></ul>
  21. 21. Broadcasting, Cable, the Internet and Beyond Chapter 3 <ul><li>Signal Reception - Television </li></ul><ul><li>Large Screen Televisions and HDTVs gaining in acceptance </li></ul><ul><li>Digital sets incorporate new features such as a picture-in-picture option. </li></ul><ul><li>LCD and plasma screen televisions are changing the size and shape of television </li></ul>
  22. 22. Broadcasting, Cable, the Internet and Beyond Chapter 3 <ul><li>Step 5: Storage and Retrieval </li></ul><ul><li>Analog audio storage </li></ul><ul><ul><li>Phonograph records </li></ul></ul><ul><ul><li>Cassette and reel-to-reel tapes </li></ul></ul><ul><li>Digital audio storage </li></ul><ul><ul><li>Compact Discs (CDs) and Audio DVDs </li></ul></ul><ul><ul><li>Computer hard drives (MP3s) </li></ul></ul><ul><ul><li>Digital Audio Tape (DAT) </li></ul></ul>
  23. 23. Broadcasting, Cable, the Internet and Beyond Chapter 3 <ul><li>Video Storage </li></ul><ul><li>Analog video storage </li></ul><ul><ul><li>Early standards included 2” and 3/4” videotape </li></ul></ul><ul><ul><li>1/2” VHS consumer video tape recorder </li></ul></ul><ul><li>Digital video </li></ul><ul><ul><li>Digital Versatile Disc (DVD) </li></ul></ul><ul><ul><li>Digital Video Recorder (DVRs) personal video recorder </li></ul></ul>
  24. 24. Broadcasting, Cable, the Internet and Beyond Chapter 3 <ul><li>Webcasting: Audio and Video Streaming </li></ul><ul><li>Streaming - web-based technology that allows computers to receive audio and video signals over the Internet </li></ul><ul><ul><li>Computers buffer video playback but accumulating some of the date before it starts to playback </li></ul></ul><ul><ul><li>Web sites also compress (shrink) the size of the signals it streams </li></ul></ul><ul><li>Playing sounds and moving images on the web requires multimedia capability </li></ul><ul><li>Buffering is a technique used to help stream media </li></ul>
  25. 25. Broadcasting, Cable, the Internet and Beyond Chapter 3 End of Chapter 3

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