Modern Electronic Comm.

Report
Chapter 17
Television
Modern Electronic Communication
Beasley & Miller
Modern Electronic Communication 9th edition
Jeffrey S. Beasley and Gary M. Miller
Copyright ©2008 by Pearson Education, Inc.
Upper Saddle River, New Jersey 07458
All rights reserved.
Television
• Digital Television (DTV)
• High Definition TV (HDTV)
 Began transmission in 1999
 All stations on the air in 2009
 Old NTSC (analog) signal is no longer
transmitted
• National Television System Committee
(NTSC)
Modern Electronic Communication 9th edition
Jeffrey S. Beasley and Gary M. Miller
Copyright ©2008 by Pearson Education, Inc.
Upper Saddle River, New Jersey 07458
All rights reserved.
Figure 17-1 The (a) HDTV screen ratio and (b) NTSC screen ratio format, shown for comparison.
Modern Electronic Communication 9th edition
Jeffrey S. Beasley and Gary M. Miller
Copyright ©2008 by Pearson Education, Inc.
Upper Saddle River, New Jersey 07458
All rights reserved.
• Advanced Television System Committee
(ATSC)
 Came up with 16 by 9 format
 Also defined standard definition television
(SDTV)
Modern Electronic Communication 9th edition
Jeffrey S. Beasley and Gary M. Miller
Copyright ©2008 by Pearson Education, Inc.
Upper Saddle River, New Jersey 07458
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Video Signal
• ITU-R 601 4:2:2 format
• International standard for digitizing
component video
• Base sampling frequency of 3.375 MHz
Modern Electronic Communication 9th edition
Jeffrey S. Beasley and Gary M. Miller
Copyright ©2008 by Pearson Education, Inc.
Upper Saddle River, New Jersey 07458
All rights reserved.
Video Signal
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Luminance [Y]:Red-luminance [R-Y]:Blue-luminance [B-Y]
4
2
2
Video signal composed of red, green, and blue (RGB)
Luminance is the black and white detail
Y, R-Y, and B-Y are converted to digital signal using Pulse Code
Modulation (PCM) at 3.375 MHz base rate.
10-bit sampling is used
Luminance is sampled at 4 times the base rate
Red-luminance and Blue-luminance at 2 times the base rate
They are time-division-multiplexed (TDM) together at 270 Mbps
Modern Electronic Communication 9th edition
Jeffrey S. Beasley and Gary M. Miller
Copyright ©2008 by Pearson Education, Inc.
Upper Saddle River, New Jersey 07458
All rights reserved.
Video Signal
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Channel
Sample Rate
Bit Rate
Luminance Channel 4 X 3.375 MHz = 13.5 MHz x 10 bits/sample = 135 Mbps
R-Y channel
2 X 3.375 MHz = 6.75 MHz x 10 bits/sample = 67.5 Mbps
B-Y channel
2 X 3.375 MHz = 6.75 MHz x 10 bits/sample = 67.5 Mbps
Serial data bit rate of 270 Mbps = 135 + 67.5 + 67.5
MPEG2 is used for data compression to fit in 6 MHz bandwidth
Motion Pictures Expert Group (MPEG)
Modern Electronic Communication 9th edition
Jeffrey S. Beasley and Gary M. Miller
Copyright ©2008 by Pearson Education, Inc.
Upper Saddle River, New Jersey 07458
All rights reserved.
Audio Signal
• Digital Audio Compression (AC-3) developed by Dolby
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Laboratories
Provides five full-bandwidth audio channels (3 Hz to 20
kHz)
Left, center, right, and left-right surround-sound channels
Also one low-frequency enhancement channel at 3 Hz to
120 Hz
5.1 Channel Input (5 full and 1 reduced)
6 channels are multiplexed together to 5.184 Mbps
Compressed to 384 kbps
Modern Electronic Communication 9th edition
Jeffrey S. Beasley and Gary M. Miller
Copyright ©2008 by Pearson Education, Inc.
Upper Saddle River, New Jersey 07458
All rights reserved.
Figure 17-2 A block diagram of the ATSC digital transmission system.
Modern Electronic Communication 9th edition
Jeffrey S. Beasley and Gary M. Miller
Copyright ©2008 by Pearson Education, Inc.
Upper Saddle River, New Jersey 07458
All rights reserved.
Transmission
• 8VSB – 8–level vestigial-sideband modulator
• I (In-phase) and Q (Quadrature)
• Exciter has 6 parts
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
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
Frame synchronizer to synchronize the MPEG2 data packets
Data randomizer to make data appear random to make the RF spectrum be flat across the
channel so data will fit in 6 MHz bandwidth
REED Solomon Encoder for error correction
Data Interleaver – interleaves data to reduce interference
Trellis Encoder – more error correction
Pilot/Sync Insertion
Modern Electronic Communication 9th edition
Jeffrey S. Beasley and Gary M. Miller
Copyright ©2008 by Pearson Education, Inc.
Upper Saddle River, New Jersey 07458
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Figure 17-3 (a) The 8VSB and (b) the 64-QAM constellations. (Courtesy of Harris Broadcast.)
Modern Electronic Communication 9th edition
Jeffrey S. Beasley and Gary M. Miller
Copyright ©2008 by Pearson Education, Inc.
Upper Saddle River, New Jersey 07458
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Figure 17-4 The 8VSB segment sync. (Courtesy of Harris Broadcast.)
Modern Electronic Communication 9th edition
Jeffrey S. Beasley and Gary M. Miller
Copyright ©2008 by Pearson Education, Inc.
Upper Saddle River, New Jersey 07458
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Figure 17-5 The 8VSB frame sync. (Courtesy of Harris Broadcast.)
Modern Electronic Communication 9th edition
Jeffrey S. Beasley and Gary M. Miller
Copyright ©2008 by Pearson Education, Inc.
Upper Saddle River, New Jersey 07458
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Figure 17-12 The display of the 8VSB constellation and the 8VSB eye diagram as displayed in the modulation detail
screen.
Modern Electronic Communication 9th edition
Jeffrey S. Beasley and Gary M. Miller
Copyright ©2008 by Pearson Education, Inc.
Upper Saddle River, New Jersey 07458
All rights reserved.
Figure 17-15 The RF spectrum for a DTV signal.
Modern Electronic Communication 9th edition
Jeffrey S. Beasley and Gary M. Miller
Copyright ©2008 by Pearson Education, Inc.
Upper Saddle River, New Jersey 07458
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Figure 17-16 Simplified TV system.
Modern Electronic Communication 9th edition
Jeffrey S. Beasley and Gary M. Miller
Copyright ©2008 by Pearson Education, Inc.
Upper Saddle River, New Jersey 07458
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Figure 17-17 An example of a CCD imaging device. (Courtesy of Hamaqmatsu Corp.)
CCD – Charge Coupled Device
Modern Electronic Communication 9th edition
Jeffrey S. Beasley and Gary M. Miller
Copyright ©2008 by Pearson Education, Inc.
Upper Saddle River, New Jersey 07458
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Figure 17-18 Simplified scanning representation.
Modern Electronic Communication 9th edition
Jeffrey S. Beasley and Gary M. Miller
Copyright ©2008 by Pearson Education, Inc.
Upper Saddle River, New Jersey 07458
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Figure 17-19 Interlaced scanning.
Modern Electronic Communication 9th edition
Jeffrey S. Beasley and Gary M. Miller
Copyright ©2008 by Pearson Education, Inc.
Upper Saddle River, New Jersey 07458
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Video Signal
• Horizontal Retrace - Time to move from
end of one line back to start of next lower
line
• Vertical Flyback or retrace – time to move
from bottom line to the start of the top line
• FCC stipulates that NTSC broadcasts
have 525 horizontal scanning lines.
• 40 lines are lost as result of vertical
retrace interval, so only 485 visible lines
Modern Electronic Communication 9th edition
Jeffrey S. Beasley and Gary M. Miller
Copyright ©2008 by Pearson Education, Inc.
Upper Saddle River, New Jersey 07458
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• Frame frequency – number of times per
second that complete set of 485 lines is
traced.
 30 times per second
• Flicker – need 60 frames per second so
human eye does not perceive difference
• Interlaced scanning is used to trick the
eye.
Modern Electronic Communication 9th edition
Jeffrey S. Beasley and Gary M. Miller
Copyright ©2008 by Pearson Education, Inc.
Upper Saddle River, New Jersey 07458
All rights reserved.
• First set of lines (first field) is traced in 1/60 second
• Second set of lines (second field) is then traced
• 485 lines are displayed, even lines first, then the odd
lines
• Horizontal sync between every line of video signal
• Horizontal sync for each of 525 lines in 1/30 second
• So 525 X 30 = 15.75 kHz is frequency of pulses
Modern Electronic Communication 9th edition
Jeffrey S. Beasley and Gary M. Miller
Copyright ©2008 by Pearson Education, Inc.
Upper Saddle River, New Jersey 07458
All rights reserved.
Figure 17-20 Horizontal sync pulses.
Modern Electronic Communication 9th edition
Jeffrey S. Beasley and Gary M. Miller
Copyright ©2008 by Pearson Education, Inc.
Upper Saddle River, New Jersey 07458
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Figure 17-21 Vertical retrace interval video signal.
Modern Electronic Communication 9th edition
Jeffrey S. Beasley and Gary M. Miller
Copyright ©2008 by Pearson Education, Inc.
Upper Saddle River, New Jersey 07458
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Figure 17-22 Transmitted TV signal.
Modern Electronic Communication 9th edition
Jeffrey S. Beasley and Gary M. Miller
Copyright ©2008 by Pearson Education, Inc.
Upper Saddle River, New Jersey 07458
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Figure 17-23 TV receiver block diagram.
Modern Electronic Communication 9th edition
Jeffrey S. Beasley and Gary M. Miller
Copyright ©2008 by Pearson Education, Inc.
Upper Saddle River, New Jersey 07458
All rights reserved.
Figure 17-24 VHF/UHF tuner block diagram.
Modern Electronic Communication 9th edition
Jeffrey S. Beasley and Gary M. Miller
Copyright ©2008 by Pearson Education, Inc.
Upper Saddle River, New Jersey 07458
All rights reserved.
Figure 17-25 Stagger tuning.
Modern Electronic Communication 9th edition
Jeffrey S. Beasley and Gary M. Miller
Copyright ©2008 by Pearson Education, Inc.
Upper Saddle River, New Jersey 07458
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Figure 17-26 SAW filter.
Modern Electronic Communication 9th edition
Jeffrey S. Beasley and Gary M. Miller
Copyright ©2008 by Pearson Education, Inc.
Upper Saddle River, New Jersey 07458
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Figure 17-27 Ideal IF response curve.
Modern Electronic Communication 9th edition
Jeffrey S. Beasley and Gary M. Miller
Copyright ©2008 by Pearson Education, Inc.
Upper Saddle River, New Jersey 07458
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Figure 17-28 Wavetraps.
Modern Electronic Communication 9th edition
Jeffrey S. Beasley and Gary M. Miller
Copyright ©2008 by Pearson Education, Inc.
Upper Saddle River, New Jersey 07458
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Figure 17-29 Video section block diagram.
Modern Electronic Communication 9th edition
Jeffrey S. Beasley and Gary M. Miller
Copyright ©2008 by Pearson Education, Inc.
Upper Saddle River, New Jersey 07458
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Figure 17-30 Sync separator.
Modern Electronic Communication 9th edition
Jeffrey S. Beasley and Gary M. Miller
Copyright ©2008 by Pearson Education, Inc.
Upper Saddle River, New Jersey 07458
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Figure 17-31 Horizontal deflection block diagram.
Modern Electronic Communication 9th edition
Jeffrey S. Beasley and Gary M. Miller
Copyright ©2008 by Pearson Education, Inc.
Upper Saddle River, New Jersey 07458
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Figure 17-32 Nonlinear horizontal scanning. (From Bernard Grob, Basic Television Principles and Servicing, 4th ed.,
1977; Courtesy of McGraw-Hill, Inc., New York.)
Modern Electronic Communication 9th edition
Jeffrey S. Beasley and Gary M. Miller
Copyright ©2008 by Pearson Education, Inc.
Upper Saddle River, New Jersey 07458
All rights reserved.
Figure 17-33 Horizontal system schematic.
Modern Electronic Communication 9th edition
Jeffrey S. Beasley and Gary M. Miller
Copyright ©2008 by Pearson Education, Inc.
Upper Saddle River, New Jersey 07458
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28-Sep
Modern Electronic Communication 9th edition
Jeffrey S. Beasley and Gary M. Miller
Copyright ©2008 by Pearson Education, Inc.
Upper Saddle River, New Jersey 07458
All rights reserved.
Composite video
• Composite video is the format of an
analog television (picture only) signal
before it is combined with a sound signal
and modulated onto an RF carrier
• Contains four information groups
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Video Brightness information
Horizontal Line Sync
Vertical Line Sync
Sound (Audio)
Modern Electronic Communication 9th edition
Jeffrey S. Beasley and Gary M. Miller
Copyright ©2008 by Pearson Education, Inc.
Upper Saddle River, New Jersey 07458
All rights reserved.
Composite Video
• A composite video signal combines on one wire the
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•
video information required to recreate a color picture, as
well as line and frame synchronization pulses.
The color video signal is a linear combination of the
luminance of the picture, and a modulated subcarrier
carries the chrominance or color information.
Chrominance is a combination of hue and saturation.
Hue is a pure color like red, green, or blue without tint.
Saturation is the amplitude of a given color
Tint is the shade of a color
Modern Electronic Communication 9th edition
Jeffrey S. Beasley and Gary M. Miller
Copyright ©2008 by Pearson Education, Inc.
Upper Saddle River, New Jersey 07458
All rights reserved.
Composite Video
Video
> 7.5 IRE
0 IRE
Modern Electronic Communication 9th edition
Jeffrey S. Beasley and Gary M. Miller
Sync
Pulses
< 0 IRE
Copyright ©2008 by Pearson Education, Inc.
Upper Saddle River, New Jersey 07458
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Color TV
• Color TV started in 1953
• Compatible with monochrome
• Uses same 6 MHz bandwidth
• Needed to be displayed on monochrome
• Can use unused spaces in spectrum
by interleaving
Modern Electronic Communication 9th edition
Jeffrey S. Beasley and Gary M. Miller
Copyright ©2008 by Pearson Education, Inc.
Upper Saddle River, New Jersey 07458
All rights reserved.
Figure 17-34 Interleaving process.
Modern Electronic Communication 9th edition
Jeffrey S. Beasley and Gary M. Miller
Copyright ©2008 by Pearson Education, Inc.
Upper Saddle River, New Jersey 07458
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Color Camera
• Uses 3 cameras in one – one for each color
 Red, Green, Blue
 3 cameras scan in unison
 Can create any color with these 3 primary
colors
Modern Electronic Communication 9th edition
Jeffrey S. Beasley and Gary M. Miller
Copyright ©2008 by Pearson Education, Inc.
Upper Saddle River, New Jersey 07458
All rights reserved.
Figure 17-35 Generating the electrical color signals (color camera).
Modern Electronic Communication 9th edition
Jeffrey S. Beasley and Gary M. Miller
Copyright ©2008 by Pearson Education, Inc.
Upper Saddle River, New Jersey 07458
All rights reserved.
• The 3 color signals are fed into a
transmitter processing circuit called the
matrix
• Creates the Y (luminance) and the chroma
or color signal (I and Q)
• Y signal has proportions of Red, Green,
and Blue to create a monochrome signal
for use on Black/White screens.
• The I and Q signals will contain the color
information.
Modern Electronic Communication 9th edition
Jeffrey S. Beasley and Gary M. Miller
Copyright ©2008 by Pearson Education, Inc.
Upper Saddle River, New Jersey 07458
All rights reserved.
Figure 17-36 Composite color TV transmission.
Modern Electronic Communication 9th edition
Jeffrey S. Beasley and Gary M. Miller
Copyright ©2008 by Pearson Education, Inc.
Upper Saddle River, New Jersey 07458
All rights reserved.
Figure 17-37 The composite color modulating signal.
Modern Electronic Communication 9th edition
Jeffrey S. Beasley and Gary M. Miller
Copyright ©2008 by Pearson Education, Inc.
Upper Saddle River, New Jersey 07458
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Figure 17-38 Color receiver block diagram.
Modern Electronic Communication 9th edition
Jeffrey S. Beasley and Gary M. Miller
Copyright ©2008 by Pearson Education, Inc.
Upper Saddle River, New Jersey 07458
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Figure 17-39 Color burst.
Modern Electronic Communication 9th edition
Jeffrey S. Beasley and Gary M. Miller
Copyright ©2008 by Pearson Education, Inc.
Upper Saddle River, New Jersey 07458
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Figure 17-40 Color CRT construction.
Modern Electronic Communication 9th edition
Jeffrey S. Beasley and Gary M. Miller
Copyright ©2008 by Pearson Education, Inc.
Upper Saddle River, New Jersey 07458
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To build a jumbo TV, you take thousands of these LED modules and arrange
them in a rectangular grid. For example, the grid might contain 640 by 480
LED modules, or 307,200 modules.
The computer system looks at the incoming TV signal and decides which
LEDs it will turn on and how brightly. The computer samples the intensity
and color signals and translates them into intensity information for the three
different LED colors at each pixel module.
Modern Electronic Communication 9th edition
Jeffrey S. Beasley and Gary M. Miller
Copyright ©2008 by Pearson Education, Inc.
Upper Saddle River, New Jersey 07458
All rights reserved.
Plasma TV
Modern Electronic Communication 9th edition
Jeffrey S. Beasley and Gary M. Miller
Copyright ©2008 by Pearson Education, Inc.
Upper Saddle River, New Jersey 07458
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What is Plasma?
• The central element in a fluorescent light is a plasma, a
gas made up of free-flowing ions (electrically charged
atoms) and electrons (negatively charged particles).
• In a plasma with an electrical current running through it,
negatively charged particles are rushing toward the
positively charged area of the plasma, and positively
charged particles are rushing toward the negatively
charged area.
• In this mad rush, particles are constantly bumping into
each other. These collisions excite the gas atoms in the
plasma, causing them to release photons of energy.
Modern Electronic Communication 9th edition
Jeffrey S. Beasley and Gary M. Miller
Copyright ©2008 by Pearson Education, Inc.
Upper Saddle River, New Jersey 07458
All rights reserved.
Plasma TV
To ionize the gas in a particular cell, the plasma display's computer charges
the electrodes that intersect at that cell. It does this thousands of times in a
small fraction of a second, charging each cell in turn.
Modern Electronic Communication 9th edition
Jeffrey S. Beasley and Gary M. Miller
Copyright ©2008 by Pearson Education, Inc.
Upper Saddle River, New Jersey 07458
All rights reserved.
Plasma TV
•
•
When the intersecting electrodes are charged (with a voltage
difference between them), an electric current flows through the gas
in the cell. The current creates a rapid flow of charged particles,
which stimulates the gas atoms to release ultraviolet photons.
The released ultraviolet photons interact with phosphor material
coated on the inside wall of the cell. Phosphors are substances that
give off light when they are exposed to other light. When an
ultraviolet photon hits a phosphor atom in the cell, one of the
phosphor's electrons jumps to a higher energy level and the atom
heats up. When the electron falls back to its normal level, it releases
energy in the form of a visible light photon.
Modern Electronic Communication 9th edition
Jeffrey S. Beasley and Gary M. Miller
Copyright ©2008 by Pearson Education, Inc.
Upper Saddle River, New Jersey 07458
All rights reserved.
LCD Screens
• http://www.howstuffworks.com/lcd.htm
Modern Electronic Communication 9th edition
Jeffrey S. Beasley and Gary M. Miller
Copyright ©2008 by Pearson Education, Inc.
Upper Saddle River, New Jersey 07458
All rights reserved.
LCD
• The combination of four facts makes LCDs
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possible:
Light can be polarized.
Liquid crystals can transmit and change
polarized light.
The structure of liquid crystals can be
changed by electric current.
There are transparent substances that can
conduct electricity.
Modern Electronic Communication 9th edition
Jeffrey S. Beasley and Gary M. Miller
Copyright ©2008 by Pearson Education, Inc.
Upper Saddle River, New Jersey 07458
All rights reserved.
• If we apply an electric charge to liquid
crystal molecules, they untwist. When they
straighten out, they change the angle of
the light passing through them so that it no
longer matches the angle of the top
polarizing filter. Consequently, no light can
pass through that area of the LCD, which
makes that area darker than the
surrounding areas
Modern Electronic Communication 9th edition
Jeffrey S. Beasley and Gary M. Miller
Copyright ©2008 by Pearson Education, Inc.
Upper Saddle River, New Jersey 07458
All rights reserved.
Digital TV
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•
Aspect ratio - Standard television has a 4:3 aspect ratio -- it is four
units wide by three units high. HDTV has a 16:9 aspect ratio, more
like a movie screen.
Resolution - The lowest standard resolution (SDTV) will be about
the same as analog TV and will go up to 704 x 480 pixels. The
highest HDTV resolution is 1920 x 1080 pixels. HDTV can display
about ten times as many pixels as an analog TV set.
Frame rate - A set's frame rate describes how many times it creates
a complete picture on the screen every second. DTV frame rates
usually end in "i" or "p" to denote whether they are interlaced or
progressive. DTV frame rates range from 24p (24 frames per
second, progressive) to 60p (60 frames per second, progressive).
Modern Electronic Communication 9th edition
Jeffrey S. Beasley and Gary M. Miller
Copyright ©2008 by Pearson Education, Inc.
Upper Saddle River, New Jersey 07458
All rights reserved.
When you hear someone mention a "1080i" HDTV set,
they're talking about one that has a native resolution of
1920 x 1080 pixels and can display 60 frames per
second, interlaced.
Modern Electronic Communication 9th edition
Jeffrey S. Beasley and Gary M. Miller
Copyright ©2008 by Pearson Education, Inc.
Upper Saddle River, New Jersey 07458
All rights reserved.
Figure 17-41 Color convergence yoke.
Modern Electronic Communication 9th edition
Jeffrey S. Beasley and Gary M. Miller
Copyright ©2008 by Pearson Education, Inc.
Upper Saddle River, New Jersey 07458
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Enhanced Audio
• Zenith / dbx
• Similar to FM, but better signal
Modern Electronic Communication 9th edition
Jeffrey S. Beasley and Gary M. Miller
Copyright ©2008 by Pearson Education, Inc.
Upper Saddle River, New Jersey 07458
All rights reserved.
Figure 17-42 Zenith/dbx stereo system.
Modern Electronic Communication 9th edition
Jeffrey S. Beasley and Gary M. Miller
Copyright ©2008 by Pearson Education, Inc.
Upper Saddle River, New Jersey 07458
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Figure 17-43 The Electronics WorkbenchTM Multisim circuit used to simulate the frequency spectra for a UHF
television signal.
Modern Electronic Communication 9th edition
Jeffrey S. Beasley and Gary M. Miller
Copyright ©2008 by Pearson Education, Inc.
Upper Saddle River, New Jersey 07458
All rights reserved.
Figure 17-44 The Electronics WorkbenchTM simulation of the frequency spectra for a channel 22 television signal.
Modern Electronic Communication 9th edition
Jeffrey S. Beasley and Gary M. Miller
Copyright ©2008 by Pearson Education, Inc.
Upper Saddle River, New Jersey 07458
All rights reserved.
Figure 17-45 The Electronics WorkbenchTM Multisim circuit of a high-Q bandstop circuit, or wavetrap.
Modern Electronic Communication 9th edition
Jeffrey S. Beasley and Gary M. Miller
Copyright ©2008 by Pearson Education, Inc.
Upper Saddle River, New Jersey 07458
All rights reserved.
Figure 17-46 The Bode plotter output for the wavetrap filter.
Modern Electronic Communication 9th edition
Jeffrey S. Beasley and Gary M. Miller
Copyright ©2008 by Pearson Education, Inc.
Upper Saddle River, New Jersey 07458
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