Broadcasting, Cable, the Internet and Beyond Chapter 3

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 (2003): $2,199 • Number of Napster downloads in February 2001: 2.8 billion • Number of DVD players worldwide (2002): 111 million

2. Broadcasting, Cable, the Internet and BeyondChapter 3 • Basic Principle of Media Technology • Facsimile Technology - All modes of mass communication based on this process of copying • 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 • Analog transmission loses fidelity at each phase of the process • Digital technology reduces loss of fidelity in the transduction process. • Television and radio signals begin as physical energy • Commonly referred to as light waves or sound waves

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 • Transmitting the sound of the chirping involves transducing the electrical energy into electromagnetic energy • 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 - the amount of program • Noise - the amount of interference • Signal to noise ratio - the amount of signal present compared to the amount of noise • Analog signals are subject to varying amounts of noise • The farther away from the transmitter, the more noise is present • Digital signals are subject to less noise interference than analog signals

6. Broadcasting, Cable, the Internet and BeyondChapter 3 • Digital Transmission • 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 an audio or video signal • Digital television (DTV) is growing in popularity in the U.S. • Two different digital radio systems. One system uses satellites, the other involves sending a terrestrial signal by your 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 sound 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

8. Broadcasting, Cable, the Internet and BeyondChapter 3 • Frequency and Amplitude • A radio wave may be described in terms of frequency and amplitude • Frequency is 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 is the height or depth of the wave from its normal position

9. Broadcasting, Cable, the Internet and BeyondChapter 3 • Frequency Response • How well a radio reproduces a range of audio frequencies is an example of describing its frequency response • 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 DVDs) • Minidiscs (MDs) • 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 • Standard 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 combine to form a single picture called a frame

12. Broadcasting, Cable, the Internet and BeyondChapter 3 • Video Signal Generation (Digital television DTV) • Digital television has several standards. • High Definition television (HDTV) represents the best picture quality • HDTV uses 1080 scan lines • The lowest range of scanned lines is 480 and 720 lines represents a medium range of television signals • 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 mix, 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 • 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 • 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 and TV channels 2 - 13 • Ultra High Frequency (UHF) - UHF and DTV channels, police 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 • Spectrum management - the process of defining and keeping track of what frequencies will be assigned and licensed for special purposes • Radio Classifications • AM Radio - 107 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

18. Broadcasting, Cable, the Internet and BeyondChapter 3 • Spectrum Management • Television and satellite channels • Television Classifications • VHF television - Channels 2 thru 13 • Each television channel occupies 6 Mhz of bandwidth • UHF television - Channels14 thru 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 • 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

20. Broadcasting, Cable, the Internet and BeyondChapter 3 • Step 4: Signal Reception - Radio • AM radio is ideal for car radios. • Signals can travel long distances, especially at night. • AM radio subject to static interference and limited frequency response • 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 • 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 - gaining in popularity in American homes • Digital sets incorporate new features such as a picture-in-picture option. • HDTVs are gaining acceptance • 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 • VHS consumer video tape recorder • Digital video • Digital Versatile Disc (DVD) • Digital Video Recorder (DVRs - called a personal video recorder) • Desktop Video - computers capable of recording and playing back video

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 • Web sites that stream media compress (shrink) the size of the signals • 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