1. 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
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 Beyond Chapter 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 Beyond Chapter 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 Beyond Chapter 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 Beyond Chapter 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 Beyond Chapter 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 Beyond Chapter 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 Beyond Chapter 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 Beyond Chapter 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 Beyond Chapter 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 Beyond Chapter 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 Beyond Chapter 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 Beyond Chapter 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 Beyond Chapter 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 Beyond Chapter 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 Beyond Chapter 3
Radio Bands in the Electromagnetic Spectrum
Medium Wave Band 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
Ultra High Frequency (UHF) - UHF and DTV channels , 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 Beyond Chapter 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 Channels assigned between 540 and 1700 Khz
Each AM channel occupies 10 Hz of bandwidth
FM Radio 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 Beyond Chapter 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
UHF television - Channels
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 Beyond Chapter 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 Beyond Chapter 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 Beyond Chapter 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 Beyond Chapter 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 Beyond Chapter 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 Beyond Chapter 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 Beyond Chapter 3
End of Chapter 3