Introduction to Course 2EC411 Digital Television

Engineering

Dr Usha Mehta

Syllabus

Calendar

Lesson Plan

Textbooks:

Modern Television Practice by R. R. Gulati, New

Age International Pub.

Digital Television by Herve Benoit, Third Edition,

Elsevier

Composite Satellite and Cable Television by R.

R. Gulati, New Age International Pub.

19-08-2014 2

Course Learning Outcomes

This course is being offered as a complete application/case study for

involving mostly all concepts related to electronics and

communication engineering. Upon completion of this course,

students will be able to:

Understand the concept of real signals like audio and video,

color signal and its effective conversion into electrical signal

Correlate the concept of preparation and processing of signal

required before transmission like amplification, modulation etc.

studied in earlier semesters with real life application.

Understand the concept of transmission and receiver and able

to prepare block level transmitter/receiver for given application.

Analyze various digitization methods/standards and their

effectiveness.

Select the necessary digitization standards for given application

Understand the concept of JPEG, MPEG, HDTV, TV over IP etc.

19-08-2014 3

Self Learning

Sr.

No. Topics

1 Recent Developments in Digital Television

Pl. refer: esaki.ee.boun.edu.tr/~morgul/Recent%20TV.pdf

2 Advances in TV/computer motion monitoring

Pl. refer:

http://ieeexplore.ieee.org/xpl/login.jsp?tp=&arnumber=96082&url=htt

p%3A%2F%2Fieeexplore.ieee.org%2Fxpls%2Fabs_all.jsp%3Farnum

ber%3D96082

3 Pl. learn following topics from net and go through it in detail

Video-On-Demand

Picture-In-Picture Technology

Mirror TV

19-08-2014 4

http://ieeexplore.ieee.org/xpl/login.jsp?tp=&arnumber=96082&url=http://ieeexplore.ieee.org/xpls/abs_all.jsp?arnumber%3D96082http://ieeexplore.ieee.org/xpl/login.jsp?tp=&arnumber=96082&url=http://ieeexplore.ieee.org/xpls/abs_all.jsp?arnumber%3D96082http://ieeexplore.ieee.org/xpl/login.jsp?tp=&arnumber=96082&url=http://ieeexplore.ieee.org/xpls/abs_all.jsp?arnumber%3D96082http://ieeexplore.ieee.org/xpl/login.jsp?tp=&arnumber=96082&url=http://ieeexplore.ieee.org/xpls/abs_all.jsp?arnumber%3D96082http://ieeexplore.ieee.org/xpl/login.jsp?tp=&arnumber=96082&url=http://ieeexplore.ieee.org/xpls/abs_all.jsp?arnumber%3D96082http://ieeexplore.ieee.org/xpl/login.jsp?tp=&arnumber=96082&url=http://ieeexplore.ieee.org/xpls/abs_all.jsp?arnumber%3D96082http://ieeexplore.ieee.org/xpl/login.jsp?tp=&arnumber=96082&url=http://ieeexplore.ieee.org/xpls/abs_all.jsp?arnumber%3D96082http://ieeexplore.ieee.org/xpl/login.jsp?tp=&arnumber=96082&url=http://ieeexplore.ieee.org/xpls/abs_all.jsp?arnumber%3D96082http://ieeexplore.ieee.org/xpl/login.jsp?tp=&arnumber=96082&url=http://ieeexplore.ieee.org/xpls/abs_all.jsp?arnumber%3D96082http://ieeexplore.ieee.org/xpl/login.jsp?tp=&arnumber=96082&url=http://ieeexplore.ieee.org/xpls/abs_all.jsp?arnumber%3D96082http://ieeexplore.ieee.org/xpl/login.jsp?tp=&arnumber=96082&url=http://ieeexplore.ieee.org/xpls/abs_all.jsp?arnumber%3D96082http://ieeexplore.ieee.org/xpl/login.jsp?tp=&arnumber=96082&url=http://ieeexplore.ieee.org/xpls/abs_all.jsp?arnumber%3D96082http://ieeexplore.ieee.org/xpl/login.jsp?tp=&arnumber=96082&url=http://ieeexplore.ieee.org/xpls/abs_all.jsp?arnumber%3D96082http://ieeexplore.ieee.org/xpl/login.jsp?tp=&arnumber=96082&url=http://ieeexplore.ieee.org/xpls/abs_all.jsp?arnumber%3D96082http://ieeexplore.ieee.org/xpl/login.jsp?tp=&arnumber=96082&url=http://ieeexplore.ieee.org/xpls/abs_all.jsp?arnumber%3D96082http://ieeexplore.ieee.org/xpl/login.jsp?tp=&arnumber=96082&url=http://ieeexplore.ieee.org/xpls/abs_all.jsp?arnumber%3D96082http://ieeexplore.ieee.org/xpl/login.jsp?tp=&arnumber=96082&url=http://ieeexplore.ieee.org/xpls/abs_all.jsp?arnumber%3D96082http://ieeexplore.ieee.org/xpl/login.jsp?tp=&arnumber=96082&url=http://ieeexplore.ieee.org/xpls/abs_all.jsp?arnumber%3D96082http://ieeexplore.ieee.org/xpl/login.jsp?tp=&arnumber=96082&url=http://ieeexplore.ieee.org/xpls/abs_all.jsp?arnumber%3D96082http://ieeexplore.ieee.org/xpl/login.jsp?tp=&arnumber=96082&url=http://ieeexplore.ieee.org/xpls/abs_all.jsp?arnumber%3D96082http://ieeexplore.ieee.org/xpl/login.jsp?tp=&arnumber=96082&url=http://ieeexplore.ieee.org/xpls/abs_all.jsp?arnumber%3D96082http://ieeexplore.ieee.org/xpl/login.jsp?tp=&arnumber=96082&url=http://ieeexplore.ieee.org/xpls/abs_all.jsp?arnumber%3D96082http://ieeexplore.ieee.org/xpl/login.jsp?tp=&arnumber=96082&url=http://ieeexplore.ieee.org/xpls/abs_all.jsp?arnumber%3D96082http://ieeexplore.ieee.org/xpl/login.jsp?tp=&arnumber=96082&url=http://ieeexplore.ieee.org/xpls/abs_all.jsp?arnumber%3D96082http://ieeexplore.ieee.org/xpl/login.jsp?tp=&arnumber=96082&url=http://ieeexplore.ieee.org/xpls/abs_all.jsp?arnumber%3D96082http://ieeexplore.ieee.org/xpl/login.jsp?tp=&arnumber=96082&url=http://ieeexplore.ieee.org/xpls/abs_all.jsp?arnumber%3D96082http://ieeexplore.ieee.org/xpl/login.jsp?tp=&arnumber=96082&url=http://ieeexplore.ieee.org/xpls/abs_all.jsp?arnumber%3D96082http://ieeexplore.ieee.org/xpl/login.jsp?tp=&arnumber=96082&url=http://ieeexplore.ieee.org/xpls/abs_all.jsp?arnumber%3D96082http://ieeexplore.ieee.org/xpl/login.jsp?tp=&arnumber=96082&url=http://ieeexplore.ieee.org/xpls/abs_all.jsp?arnumber%3D96082http://ieeexplore.ieee.org/xpl/login.jsp?tp=&arnumber=96082&url=http://ieeexplore.ieee.org/xpls/abs_all.jsp?arnumber%3D96082http://ieeexplore.ieee.org/xpl/login.jsp?tp=&arnumber=96082&url=http://ieeexplore.ieee.org/xpls/abs_all.jsp?arnumber%3D96082http://ieeexplore.ieee.org/xpl/login.jsp?tp=&arnumber=96082&url=http://ieeexplore.ieee.org/xpls/abs_all.jsp?arnumber%3D96082http://ieeexplore.ieee.org/xpl/login.jsp?tp=&arnumber=96082&url=http://ieeexplore.ieee.org/xpls/abs_all.jsp?arnumber%3D96082http://ieeexplore.ieee.org/xpl/login.jsp?tp=&arnumber=96082&url=http://ieeexplore.ieee.org/xpls/abs_all.jsp?arnumber%3D96082http://ieeexplore.ieee.org/xpl/login.jsp?tp=&arnumber=96082&url=http://ieeexplore.ieee.org/xpls/abs_all.jsp?arnumber%3D96082http://ieeexplore.ieee.org/xpl/login.jsp?tp=&arnumber=96082&url=http://ieeexplore.ieee.org/xpls/abs_all.jsp?arnumber%3D96082http://ieeexplore.ieee.org/xpl/login.jsp?tp=&arnumber=96082&url=http://ieeexplore.ieee.org/xpls/abs_all.jsp?arnumber%3D96082http://ieeexplore.ieee.org/xpl/login.jsp?tp=&arnumber=96082&url=http://ieeexplore.ieee.org/xpls/abs_all.jsp?arnumber%3D96082http://ieeexplore.ieee.org/xpl/login.jsp?tp=&arnumber=96082&url=http://ieeexplore.ieee.org/xpls/abs_all.jsp?arnumber%3D96082http://ieeexplore.ieee.org/xpl/login.jsp?tp=&arnumber=96082&url=http://ieeexplore.ieee.org/xpls/abs_all.jsp?arnumber%3D96082http://ieeexplore.ieee.org/xpl/login.jsp?tp=&arnumber=96082&url=http://ieeexplore.ieee.org/xpls/abs_all.jsp?arnumber%3D96082

Assessment Methods

Course TERM ASSIGNMENT (TA) LPW

Subject

Code

Subject

Name

Course

Coordinato

rs

Faculty

Involved

L T P C

Assig

nmen

ts

2 class

Tests Special Assignment *

No. of

Practica

l

Conti.

Asset

Term

End

Exam

No. WT

Type of

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nt WT

WT WT

2EC41

1

Digital

television

Dr. Usha

Mehta

Prof.

Hardik

Joshi

3 0 2 4

NA 0.6

Term

Paper 0.4 11 0.75 0.25

19-08-2014 5

Special Assignment

Term Paper Topics 3D Television

Ambilight

Broadcast Flag

CableCARD

Digital Light Processing

Digital Right Managements

Digital Video Recorder

Direct Broadcast Satellite

DVD and HD-DVD

Blue Ray Disc

Flat Panel Display

High Definition Multimedia Interface

IP TV

Laser TV Display Technology

LCD Display

Morror TV

OLED TV

P2P TV

Pay-Per-View

Personal Video Recorder

Pixelplus: Digital Filter Image

processing technology

Picture-In-Picture

Plasma Display

Remote Control

Surface Conduction Electron Emitter

Display

Video On Demand

Ultra High Definition TV

Sling Box

Time Shifting

Web TV

Evaluation in Display Technology

History of television

Audiography

Audio Restoration

History of Sound Recording

Audio Engineering

19-08-2014 6

Introduction to Television

Dr Usha Mehta

Acknowledgement

This presentation has been summarized from

various books, papers, websites and

presentations on Television Engineering all

over the world. I couldn’t remember where

these large pull of hints and work come from.

However, I’d like to thank all professors and

scientists who created such a good work on

this emerging field. Without those efforts in

this very emerging technology, these notes

and slides can’t be finished

19-08-2014 8

What is Television?

Tele: Distance, a Greek prefix

Telegraph, telephone, teletex, telescope, telecast,

telecommunication……

Vision: to see, Latin word

From early days, mankind has a desire to

see the things of far away…

In Mahabharat, Dhutrashtra….

In real world, motion picture and then came

television

19-08-2014 9

What is Television…

It contains…..

Images - Black and White Shades of Grey

Colour - Hue & Saturation

Sound - Audio Information

Data - Teletext & Other Data

Synchronisation - Specifies the Timing

Transport System - Gets all above items to

your TV

19-08-2014 10

Let’s build our own TV Transmission-

Receiver System

19-08-2014 11

19-08-2014 12

Was it happened in History the same way

you think?

19-08-2014 13

History - Ferdinand Braun - CRT 1890 Ferdinand Braun developed the

Cathode Ray Tube.

1897 developed the Cathode Ray

Oscillograph, the precursor to the radar

screen and the television tube

1907 First use of cathode ray tube to

produce the rudiments of television images.

He shared the Nobel Prize for physics in

1909 with Guglielmo Marconi for his

contributions to the development of wireless

telegraphy

19-08-2014 14

John Logie Baird - Basic TV Oct 1923 John Logie Baird was the first

person anywhere in the world to

demonstrate true television in the form

of recognisable images, instantaneous

movement and correct gradations in light

and shade. Scanning was done mechanically with a Nipkow

disc. The first 30 line picture transmitted was a Maltese

cross.

1927 he also demonstrated video recording

1928 transatlantic television

1937 the broadcast of high definition colour pictures

1941 stereoscopic television in colour

1944 the multi-gun colour television tube, the forerunner of

the type used in most homes today 19-08-2014 15

Early Mechanical Approach to TV Mechanical Nipkow discs were used to scan the

image and reconstitute the image at the receiver.

PE cells were used to capture the image. The

problem was synchronising the disks

19-08-2014 16

30 Line Mechanical TV

19-08-2014 17

Electronic Television - Farnsworth

In 1922 at Age 14 Philo Farnsworth

had the idea of how to make Electronic

Television possible.

Sept. 7, 1927, Farnsworth painted a

square of glass black and scratched a

straight line on the centre. The slide

was dropped between the Image

Dissector (the camera tube that

Farnsworth had invented earlier that

year) and a hot, bright, carbon arc

lamp.

On the receiver they saw the straight-

line image and then, as the slide was

turned 90 degrees, they saw it move.

This was the first all-electronic

television picture ever transmitted.

19-08-2014 18

Vladimir Zworykin - Iconoscope

In 1923 Vladimir Zworykin of RCA made a patent application for a

camera device, and by 1933 had developed a camera tube he called

an Iconoscope. Although Zworykin submitted his patent application

first after many years of legal battle Farnsworth was acknowledged

as the inventor of electronic television.

By the end of 1923 he had also produced a picture display tube, the

"Kinescope“

19-08-2014 19

Significant Television Inventions

These inventions were the underlying basis of the

development of Television as we know it today

19-08-2014 20

Evolution 1857: Isolation of selenium by Bergelius

1873: Discovery of light sensitive property of Selenium

1884:Nipko’s Disk

1908: All Electronic TV system by A.A. Campbell

1923: Iconoscope by V. Zworykin

1926:TV transmission for members of Royal Institution

1928: Color Transmission

1930: Similar idea by Fransworth

After years of patent battles, Fransworth won but RCA (Radio

Corporation of America) bought ideas from both

1936: Britain strarted TV Program

1939: USA

1959:India

1982:Color TV in India 19-08-2014 21

Picture Transmission Picture info is optical and broken in “Pixels”

Ideally infinite pixels

Simultaneous pick-up of info is not possible so

scanning

With scanning, the problem of “Image Storage”

Energy conversion from optical to electrical form by

camera using scanning process

Photoelectric Effects

Photoemission

Photo conductivity

19-08-2014 22

Photoemission

Light is in the forms of bundles of energy

called photons

When these photons of light are bomarded

on certain metals, the electrons are

dislodged from the surface

Caesium Silver, Bismuth, Lithium etc

Photons are proportion to intensity of light

Iconoscope, Image Orthicone etc use this

principal

19-08-2014 23

Photoconductivity

The resistance of semiconductor material is

proportional to light incidenting on it.

Selenium, Antimony Trisulphide, Lead

oxide etc.

Vidicon, Plumbicon etc. use this effect

19-08-2014 24

Charge Coupled Device

A charge-coupled device (CCD) is a light-

sensitive integrated circuit that stores and

displays the data for an image in such a

way that each pixel (picture element) in the

image is converted into an electical charge,

the intensity of which is related to a color in

the color spectrum. CCDs are now

commonly included in digital still and video

cameras.

19-08-2014 25

In the absence of an external electric field the photo

generated hole and electron will quickly re-combine and be

lost. In a CCD an electric field is introduced to sweep these

charge carriers apart and prevent recombination.

19-08-2014 26

19-08-2014 27

Four Primary Functions

Charge Generation

Collection & storage

Charge transfer

Charge measurements

19-08-2014 28

19-08-2014 29

19-08-2014 30

19-08-2014 31

CMOS Sensor/Active Pixel Sensor

19-08-2014 32

photodiode

CCD

High quality

Low noise images

More matured devices

because of mass

production

CMOS

Because of large

number of transistors,

some of photons lost

and light sensitivity is

low

Lower quality,

resolution, sensitivity

Lower cost and longer

battery life

19-08-2014 33

Vidicon Camera Tube

19-08-2014 34

Colour Camera

19-08-2014 35

Partially silvered

Basic Monochrome

Television Transmitter

19-08-2014 36

Basic Monochrome

Television Receiver

19-08-2014 37

Elements of Picture Tube

19-08-2014 38

Elements of Color Picture Tube

19-08-2014 39

Display Technologies

Cathode Ray Tube (CRT)

Vacuum Florescent Display (VFD)

Field Emission Display (FED)

Flat Panel Display

Light Crystal Display (LCD)

Plasma Display Panel (PDP)

Rear projection/ front projection

Digital Light Processing DLPs

Organic Light Emitting Diode (OLED)

19-08-2014 40

19-08-2014 41

DLP

19-08-2014 42

How LCD Works

LCD Monitor Technique Animation.mp4

19-08-2014 43

LCD Monitor Technique Animation.mp4

19-08-2014 44

Geometric Form

Frame adopted is rectangle with Aspect

Ratio (Width/Height) = 4/3

Reasons: 1.Most of the motion occurs in horizontal plane

2.Eyes can view more easily and comfortably

3.For enabling direct television transmission of film programs

without wastage of any film area - Motion pictures use a

rectangular frame with width/height ratio of 4/3 – so

adopted this aspect ratio in TV

19-08-2014 45

Aspect Ratio

Not the actual size but aspect ratio of the

size of the picture produced on the receiver

screen and the picture being televised must

be the same.

achieved by setting the magnitude of the current

in the deflection coils to correct values both at

the TV camera and the receiving picture tube

19-08-2014 46

Various Aspect Ratio

4:3 => old TV and Computer Monitor

3:2=>classic 35mm movie in silent era

8:5=>credit card

5:3=>European wide screen

1.85:1=>US wide screen

2.39:1=>current wide screen

16:9=>HD video

19-08-2014 47

Aspect Ratio Comparison

19-08-2014 48

Why 16:9? Dr. Powers cut out rectangles with

equal areas, shaped to match each of

the popular aspect ratios. When

overlapped with their center points

aligned, he found that all of those

aspect ratio rectangles fit within an

outer rectangle with an aspect ratio of

1.77:1 and all of them also covered a

smaller common inner rectangle with

the same aspect ratio 1.77:1. The

value found by Powers is exactly

the geometric mean of the extreme

aspect ratios, 4:3 (1.33:1) and 2.35:1,

which is coincidentally close to 16:9

(1.77:1). Applying the same geometric

mean technique to 16:9 and 4:3 yields

the 14:9 aspect ratio, which is likewise

used as a compromise between these

ratios.

19-08-2014 49

http://en.wikipedia.org/wiki/Geometric_meanhttp://en.wikipedia.org/wiki/Geometric_meanhttp://en.wikipedia.org/wiki/Geometric_meanhttp://en.wikipedia.org/wiki/14:9http://en.wikipedia.org/wiki/14:9http://en.wikipedia.org/wiki/14:9

Synchronization

Same coordinated should be scanned at

any instant both by the camera tube beam

and the picture tube beam

achieved by transmitting synchronizing pulses

along with the picture information

19-08-2014 50

Image Continuity

Persistence of vision : sensation produced when

nerves of the eye’s retina are stimulated by incident

light does not cease immediately after the light is

removed but persists for about 1/16th of a second

Scanning rate is made greater than 16 per second

i.e. number of pictures shown per second is more

than 16 – hence our eye can able to integrate the

changing levels of brightness in the scene

Present day motion pictures – 24 still pictures of

the scene are taken per second and projected on

the screen at the same rate

19-08-2014 51

Scanning

19-08-2014 52

Horizontal Scanning

19-08-2014 53

Linear rise of current in the deflection coils deflects the beam across

the screen with a continuous uniform motion for the trace from left

to right .

At the peak of the rise, the saw tooth wave reverses its direction and

decreases rapidly to its initial value, producing the retrace or flyback

Vertical Scanning

19-08-2014 54

Because of the motion in the scene being televised, the

information or brightness at the top of the target plate or

picture tube screen normally changes by the time the beam

returns to the top to recommence the whole process. This

information is picked up during the next scanning cycle and

the whole process is repeated 25 times to cause an illusion of

continuity

During the horizontal and vertical retrace intervals, the

scanning beams at the camera tube and the picture tube are

blanked and no picture information is either picked up or

reproduced

Synchronizing pulses are transmitted during this period –

resulting in distortionless reproduction of the picture details

19-08-2014 55

No. of Scanning Lines Most scenes have brightness gradations in

the vertical directions

The ability of the scanning beam to allow

reproduction of electrical signals according

to these variations and the capability of the

human eye to resolve these distinctly (while

viewing) depends on the total number of

lines employed for scanning

Number of scanning lines is judged by

considering the bar pattern as shown

where alternate lines are black and white

19-08-2014 56

No. of Scanning Lines….. If the thickness of the scanning beam is equal to the width of

each black and white bar and the number of scanning

lines is chosen equal to the number of bars, then the

electrical information corresponding to the brightness of each

bar will be correctly produced during the scanning

process

Greater the number of lines, better will be the resolution

19-08-2014 57

Critical Viewing Distance

The total number of lines is limited by the resolving capability

of the human eye at the minimum viewing distance

19-08-2014 58

With reasonable brightness variation and

a minimum viewing distance of 4 times

the picture height (D/H = 4), the angle

that any two adjacent elements must

subtend at the eye for distinct resolution

is approximately one minute (1/60

degree)

19-08-2014 59

In practice, the picture elements are not arranged as equally

spaced elements but have random distribution of black, grey

and white depending on the nature of the picture details.

Analysis and tests suggests that about 70% of the total line

get separately scanned in the vertical direction and the

remaining 30% get merged with other elements due to the

beam spot falling equally on two consecutive lines (as shown

in figure)

Thus the effective number of lines distinctly resolved Nr = Nv × K

where K is the resolution factor whose value lies between 0.65 & 0.75

Assuming the value of k = 0.7; Nr = 860 × 0.7 = 602

19-08-2014 60

Other factors affecting choice of

No. of Scanning Lines

Improvement in resolution is not very significant with line

numbers > 500

Channel bandwidth increases with the increase in number of

lines

- cost of the system increases

- reduces the number of channels in a given VHF/UHF

transmission band

As a compromise between quality and cost, the total number of

lines (inclusive of those lost during vertical retrace) has been

chosen to be 625 in the 625-B monochrome TV system.

19-08-2014 61

Flicker

25 frames per second in television picture is not

rapid enough to allow the brightness of one picture

or frame to blend smoothly into the next during the

time when the screen is blanked between

successive frames

Produces flicker

Eliminated in motion pictures by showing each

picture twice – ie 48 views of the scene per second –

still the same 24 picture frames per second

ie each picture frame twice

It means more data to transfer with rapid speed

means more bandwidth may require……. 19-08-2014 62

Scanning

Progressive Interlaced

19-08-2014 63

Interlaced Scanning

19-08-2014 64

Pixel Aspect Ratio and Scanning

Progressive VS Interlaced Video Modes and

Pixel Aspect Ratio.mp4

19-08-2014 65

Progressive VS Interlaced Video Modes and Pixel Aspect Ratio.mp4Progressive VS Interlaced Video Modes and Pixel Aspect Ratio.mp4

Resolution

The ability of the image reproducing system

to represent the fine structure of an object

is known as its resolving power or

resolution.

19-08-2014 66

Vertical Resolution The extent to which the scanning system is

capable of resolving picture details in the

vertical direction is referred to as its vertical

resolution.

Vr = Na x K Na = No. of effective lines =625-40 (during retrace) =585

K=Kell’s factor, ratio between the number of lines of

resolution perceived and the number of pixels or TV scan

lines being used (across the same distance) taking into

account degradation that might occur in any or all steps

of the image reproduction process = 0.69 approx.

Vr = 585 X 0.69 = 400lines

19-08-2014 67

Horizontal Resolution

Aiming at equal vertical and horizontal

resolution and as such the number of

alternate black and white bars that should

be considered is equal to Na × aspect ratio =

585 × 4/3 = 780

But effective number of alternate black and

white segment = N = Na × aspect ratio × k =

585 × 4/3 × 0.69 = 533

19-08-2014 68

Bandwidth for Monochrome Signal To resolve the 533 squares or picture elements the scanning spot must

develop a video signal of square wave nature switching continuously along

the line between voltage levels corresponding to black and peak white.

Since along one line there are 533/2 ≈ 267 complete cyclic changes, 267

complete square wave cycles get generated during the time the beam takes to

travel along the width of the pattern.

Thus the time duration th of one square wave cycle is equal to

19-08-2014 69

Let’s try…..

The relevant data for a closed circuit TV system is given

below. Calculate the highest modulating frequency that will

be generated while scanning the most stringent case of

alternate black and white dots for equal vertical and

horizontal resolution.

No. of lines = 250

Interlace ratio = 1 : 1

Picture repetition rate = 50/sec

Aspect ratio = 4/3

Vertical retrace time = 10% of the picture frame time

Horizontal retrace time = 20% of the total line time

Assume resolution factor = 0.8

19-08-2014 70

Influence of number of lines on

bandwidth…

Effect of interlaced scanning on bandwidth

Effect of field frequency on bandwidth

Bandwidth requirement of transmitting

synchronization pulses…

19-08-2014 71

1080p (aka Full HD/ FHD and BT.709) is a

set of HDTV high-definition video modes

characterized by 1080 horizontal lines of

vertical resolution[1] and progressive scan,

as opposed to interlaced, as is the case with

the 1080idisplay standard. The term

usually assumes a widescreen aspect

ratio of 16:9, implying a resolution of

1920x1080 (2.1 megapixel) often marketed

as Full HD.

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http://en.wikipedia.org/wiki/Graphics_display_resolution#FHDhttp://en.wikipedia.org/wiki/BT.709http://en.wikipedia.org/wiki/High-definition_televisionhttp://en.wikipedia.org/wiki/High-definition_videohttp://en.wikipedia.org/wiki/High-definition_videohttp://en.wikipedia.org/wiki/High-definition_videohttp://en.wikipedia.org/wiki/Display_resolutionhttp://en.wikipedia.org/wiki/1080p#cite_note-1http://en.wikipedia.org/wiki/Progressive_scanhttp://en.wikipedia.org/wiki/Interlaced_videohttp://en.wikipedia.org/wiki/1080ihttp://en.wikipedia.org/wiki/Widescreenhttp://en.wikipedia.org/wiki/Aspect_ratio_(image)http://en.wikipedia.org/wiki/Aspect_ratio_(image)http://en.wikipedia.org/wiki/16:9http://en.wikipedia.org/wiki/Megapixel

Why odd no. of lines in interlaced

scanning?

Interlaced error

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Bandwidth for Colour signal

For a very small colour details, the eye can

perceive only its brightness, not its hue, so

large bandwidth is not required for colour

signal

Perception of colours by the eye is limited to

objects which result in a video frequency

output up to about 1.5 MHz.

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Brightness and Contrast

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Brightness: by adding/subtracting equal dc

value to each pixel

Contrast: by increasing/decreasing the

peak-to-peak amplitude or differences

between white and black level

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Luminance, Hue and Saturation Luminance/Brightness

Amount of light intensity as perceived by the eye

regardless of the color

Hue/tint

Predominant spectral colour of the received

light.

Different hue has different wavelengths of

spectral radiation

Saturation

The spectral purity of the colour light

An indication of how little the color is diluted by

white

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Hue, Saturation and Luminance

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Questions!!!!!

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Were you waiting for this slide to come???

Thanks!

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