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Broadcasting, Cable, the Internet and Beyond Chapter 3

Broadcasting, Cable, the Internet and Beyond Chapter 3. Quick Facts Bandwidth of an FM channel: 200 kilohertz Bandwidth of a digital television channel: 6 megahertz First high-definition TV broadcasts: 1998 Cost of 51” digital HDTV set (1999): $5,000

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Broadcasting, Cable, the Internet and Beyond Chapter 3

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  1. Broadcasting, Cable, the Internet and BeyondChapter 3 • Quick Facts • Bandwidth of an FM channel: 200 kilohertz • Bandwidth of a digital television channel: 6 megahertz • First high-definition TV broadcasts: 1998 • Cost of 51” digital HDTV set (1999): $5,000 • Cost of 51” digital HDTV set (2006): $1,699 • Percent of dads hoping for a consumer electronics gift on Father’s Day, 2006: 42

  2. Broadcasting, Cable, the Internet and BeyondChapter 3 • Basic Principle of Media Technology • Facsimile Technology - All modes of mass communication based on this process • Fidelity - a way to describe how faithfully a facsimile represents the original • High Fidelity is reproduction that closely approximates the original signal • Radio waves can be used to transmit facsimiles of pictures and sounds

  3. Broadcasting, Cable, the Internet and BeyondChapter 3 • Transduction • Transduction - the process of changing one form of energy into another form • Both analog and digital broadcasting involves different kinds of transductions • Noise in the transmission reduces the fidelity of the signal • Analog transmission loses fidelity at each phase of the process • Digital technology reduces lose of fidelity in the transduction process. • Television and radio signals begin as physical energy • Commonly referred to as light waves or sound waves • More and more broadcast signals are now in digital form

  4. Broadcasting, Cable, the Internet and BeyondChapter 3 • Examples of transduction • Capturing sound of a bird chirping using a microphone involves the transduction of sound waves into electricity • Making a recording of the bird involves making a facsimile of the original sound • Transmitting the sound of the chirping involves the transduction of the electrical energy into electromagnetic energy • The audio of a bird chirping is superimposed on the carrier wave of the broadcast channel • At home, our antenna detects the transmitted signal and begins to reverse the transduction process

  5. Broadcasting, Cable, the Internet and BeyondChapter 3 • Signal and Noise • Signal - an electrical impulse or amount of power • Noise - the amount of unwanted interference • Signal to noise ratio - the amount of pure signal present compared to the amount of unwanted noise • Analog signals are subject to varying amounts of noise • As signal goes farther away from the transmitter, more noise is added • Digital signals are subject to less noise interference than analog signals

  6. Broadcasting, Cable, the Internet and BeyondChapter 3 • Digital Transmission • Digital technology uses binary codes • Binary codes use sequences of 0s and 1s - called bytes • Today, both digital radio and television signals have been approved for broadcasting • Digital transmission - sending binary data to receivers capable of converting this data back into audio or video signals • Digital television (DTV) is growing in popularity in the U.S. • Two different digital radio systems exist. One uses satellites, the other involves sending a terrestrial signal by the local broadcaster

  7. Broadcasting, Cable, the Internet and BeyondChapter 3 • Oscillation and the Waveform • Oscillation - a basic concept of audio and video signal processing • Examples - vibration of air produced by our mouths makes the sounds we hear and vibration of light make up all the images we see • Electromagnetic waves are subject to oscillation • The oscillations of a radio wave defines its frequency • Waveform - the footprint or image of an oscillation we use to visualize the presence of the invisible

  8. Broadcasting, Cable, the Internet and BeyondChapter 3 • Frequency and Amplitude • A radio wave may be described in terms of frequency and amplitude • Frequency - the number of waves that pass a given point in a given time • Frequency is usually measured in hertz (Hz) • The higher the frequency the shorter the wavelength • Amplitude (power) - the height or depth of the wave from its normal position

  9. Broadcasting, Cable, the Internet and BeyondChapter 3 • Frequency Response • Frequency Response - range of frequencies that a radio set is capable of receiving • Example : How well a radio reproduces a range of audio frequencies • The ear can hear a frequency range of approximately 10 octaves, from a low of 20 Hz to a high of 20,000 Hz • CDs can reproduce the entire range of audio frequencies that the human ear can hear

  10. Broadcasting, Cable, the Internet and BeyondChapter 3 • Steps in Signal Processing • Step One - Signal Generation • Mechanical methods of reproducing sound • Microphones • Phonograph records • Tape recorders • Digital methods of reproducing sound • Digital Audio Tape (DAT) • Compact Discs (CDs) and Digital Versatile Disks (DVDs) • Minidiscs (MD) • Computer files (MP3s)

  11. Broadcasting, Cable, the Internet and BeyondChapter 3 • Video Signal Generation (NTSC) • Television’s ability to transmit images is based on the technology of scanning • Analog U.S. television scans a television picture using two fields of information for a total of 525 lines • Each field consists of 262 1/2 horizontal scanning lines • The two fields interlace to combine to form a single picture called a frame

  12. Broadcasting, Cable, the Internet and BeyondChapter 3 • Video Signal Generation (Digital television DTV) (Cont.) • Digital television has several standards • High Definition Television (HDTV) represents the best picture quality • HDTV uses either 480, 720 or 1080 scanning lines, 480 being the lowest range, 720 medium, and 1080 being the highest • Digital television channels are free of noise and look better than comparable analog television

  13. Broadcasting, Cable, the Internet and BeyondChapter 3 • Step 2 - Signal Amplification and Processing • Audio Signal Processing • Amplifiers boost or modify electrical signals • Mixing consoles and control boards are used to input, select, control, mix, combine, route, and process signals • Today many signal processing functions can be accomplished using a computer (Desktop Audio)

  14. Broadcasting, Cable, the Internet and BeyondChapter 3 • Step 2 - Signal Amplification and Processing (Cont.) • Video Amplification and Processing • Video signals are mixed using a switcher • Special effects generators provide keying and chromakey effects to a television picture • Digital Video Effects provide special effects that can manipulate the size and position of a picture • Computers are being used today to manipulate and edit video images (Desktop Video)

  15. Broadcasting, Cable, the Internet and BeyondChapter 3 • Step 3 - Signal Transmission • Electromagnetic Spectrum is very large • Radio and television signals occupy a portion of the electromagnetic spectrum • Radio and television stations are assigned specific frequencies • Carrier wave - the signal produced by a station’s transmitter • AM - The carrier wave is modulated • FM - The frequency is modulated • Only a small part of the electromagnetic spectrum is utilized for AM and FM broadcasting • AM and FM radio stations use different portions of the spectrum

  16. Broadcasting, Cable, the Internet and BeyondChapter 3 • Radio Bands in the Electromagnetic Spectrum • Medium Wave Band - 107 AM channels, air and marine radio • High Frequency Band - International Shortwave, CB, and Ham radio • Very High Frequency (VHF) - FM radio, police radio, airline navigation systems, and TV channels 2 - 13 • Ultra High Frequency (UHF) - UHF and DTV channels 14 - 38, police and taxi mobile radio, radar and weather satellites • Super High Frequency (SHF) - Ku and C band satellites, Microwave transmission, air navigation • Extremely High Frequency (EHF) -special military communications

  17. Broadcasting, Cable, the Internet and BeyondChapter 3 • Spectrum management - the process of defining and keeping track of what frequencies will be assigned and licensed for special purposes • The FCC decides who gets a broadcast license is • Radio Classifications • AM Radio - 117 Channels assigned between 540 and 1700 Khz • Each AM channel occupies 10 Hz of bandwidth • FM Radio - 100 Channels assigned between 88 and 108 Mhz • Each FM channel occupies 200 Khz of bandwidth • Commercial FM is divided into three zones covering the US • January 2000, new low-powered FM was created • Digital Radio (HD) - approved for broadcasters to create digital services in addition to analog broadcasts.

  18. Broadcasting, Cable, the Internet and BeyondChapter 3 • Signal Transmission (cont.) • Spectrum Management -Television and satellite channels • Television Classifications and Basics • Each television channel occupies 6 Mhz of bandwidth • VHF television - Channels 2 - 13 • UHF television - Channels14 - 83 • UHF channel assignments include new digital television channels (DTV) • Satellite TV - Direct Broadcast Satellite (DBS) uses the Super High Frequency band (SHF)

  19. Broadcasting, Cable, the Internet and BeyondChapter 3 • Wired Communication • Cable TV uses coaxial cable as a transmission medium • Coaxial cable is capable of transmitting a large number of channels through the wire • Digital compression increases channel capacity even more • Addressability - the ability to send a program to some households but not others. • Addressability is used for pay-per-view (PPV) TV • Fiber Optics uses digital technology - almost unlimited bandwidth • Fiber can carry television, telephone and broadband information

  20. Broadcasting, Cable, the Internet and BeyondChapter 3 • Step 4: Signal Reception - Radio • AM radio is ideal for car radios • Signals travel long distances, especially at night • AM is subject to static interference and limited frequency response. Receiver quality is often poor • FM radio is a full fidelity medium but is limited to line of sight transmission • FM requires a long antenna • Signals tend to be blocked by buildings or moving objects • Radio Broadcast Data Systems or ‘Smart’ radios provide some functionality • Satellite radios need a special antenna and receiver • Satellite services are pay services

  21. Broadcasting, Cable, the Internet and BeyondChapter 3 • Signal Reception - Television • Large Screen Televisions and HDTVs gaining in acceptance • Digital sets incorporate new features such as a picture-in-picture option. • LCD and plasma screen televisions are changing the size and shape of television

  22. Broadcasting, Cable, the Internet and BeyondChapter 3 • Step 5: Storage and Retrieval • Analog audio storage • Phonograph records • Cassette and reel-to-reel tapes • Digital audio storage • Compact Discs (CDs) and Audio DVDs • Computer hard drives (MP3s) • Digital Audio Tape (DAT)

  23. Broadcasting, Cable, the Internet and BeyondChapter 3 • Video Storage • Analog video storage • Early standards included 2” and 3/4” videotape • 1/2” VHS consumer video tape recorder • Digital video • Digital Versatile Disc (DVD) • Digital Video Recorder (DVRs) personal video recorder

  24. Broadcasting, Cable, the Internet and BeyondChapter 3 • Webcasting: Audio and Video Streaming • Streaming - web-based technology that allows computers to receive audio and video signals over the Internet • Computers buffer video playback but accumulating some of the date before it starts to playback • Web sites also compress (shrink) the size of the signals it streams • Playing sounds and moving images on the web requires multimedia capability • Buffering is a technique used to help stream media

  25. Broadcasting, Cable, the Internet and BeyondChapter 3 End of Chapter 3

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