Middleton W.M. (ed.) Reference Data for Engineers: Radio, Electronics, Computer and Communications

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35-32

SMPTE 255M, Television Analog Recording-

SMPTE 256M Television-Specifications for Video

25.4-mm Type J-High-Definition Signals

Tape Leader

RECQMMENDED

PRACTICES

RP 9-1986, Dimensions of Double-Frame 35-mm 2x2

Slides for Precise Applications in Television

RP 14-1988, Plotting Data from Sensitometric Strips

Exposed on Type

(Intensity Scale) Sensitometers

RP 15-1988, Calibration of Densitometers Used for

Black-and-white Photographic Density Measure-

ment

RP 27.1-1989, Specifications for Operational Align-

ment Test Pattern for Television

RP 27.2- 1989, Specifications for Operational Registra-

tion Test Pattern for Multiple-Channel Television

Cameras

RP 27.3-1989, Specifications for Safe Action and Safe

Title Areas Test Pattern for Television Systems

RP 27.4-1985, Specifications for Operational Test Pat-

tern for Checking Jitter, Weave and Travel Ghost in

Television Projectors

RP 27.5-1989, Specifications for Mid-Frequency Re-

sponse Test Pattern for Television

RP 27.7-1987, Specifications for Gray-Scale Opera-

tional Alignment Test Pattern for Telecine Cameras

RP 37-1 969, Color Temperature for Color Television

Studio Monitors (R1982)

RP 38.1-1989, Specifications for Deflection Linearity

Test Pattern for Television

RP 41-1983, Evaluation of Color Films Intended for

Television

RP 46-1990, Density of Color and Black-and-white

Films, Prints and Slides for Television

RP 47-1985, Electronic Method of Dropout Detection

and Counting (R1989)

RP 61-1989, Specifications for Azimuth Test Film for

8-mm Type

Audio Reproducers, Magnetic Type

RP 62-1989, Specifications for Flutter Test Film for

8-mm Type

Audio Reproducers, Magnetic Type

RP 63-1989, Specifications for Sound-Focusing Test

Film for 16-mm Audio Reproducers, Photographic

Type

RP 64- 1987, Specifications for Audio-Focusing Test

Film for 35-mm Audio Reproducers, Photographic

Type

RP 65-1987, Step Optical Reduction Printing of

35-mm Images to 16-mm Prints and Duplicate Nega-

tives

RP 66-1987, Step Optical Enlargement Printing

35-mm Images from 16-mm Images

RP 67-1989, Specifications for Buzz-Track Test Film

for 16-mm Motion-Picture Audio Reproducers, Pho-

tographic Type

RP 68-1984. Specifications for Buzz-Track Test Film

for 35-mm Motion-Picture Photographic Audio Re-

producers

RP 69-1989, Specifications for Scanning-Beam Uni-

formity Test Film for 35-mm Motion-Picture Audio

Reproducers

RP 70-1989, Specifications for Flutter Test Film for

16-mm Audio Reproducers, Photographic Type

RP 71-1977, Setting Chromaticity and Luminance of

White for Color Television Monitors Using Shadow-

Mask Picture Tubes

RP 72-1977, Specifications for an Illuminator of Test

Pattern Transparencies for Television Studio Cameras

(R1988)

RP 85-1985, Tracking-Control Record for 1-in Type C

Helical-Scan Video Tape Recording

RP 86-1985, Video Record Parameters for 1-in Type

Helical-Scan Video Tape Recording

RP 87-1986, Reference Carrier Frequencies, Pre-

Emphasis Characteristic and Audio and Control

Signals for 3/4-in Type E Helical-Scan Video Tape

Cassette Recording

RP 88-1986, Reference Carrier Frequencies and Pre-

Emphasis Characteristic for 1/2-in Type F Helical-

Scan Video Tape Recording

RP 90- 1979, Specifications for Magnetic-Type Audio

Level and Multifrequency Test Film for 16-mm

Sound Reproducers

RP 96-1988, Specifications for Subjective Reference

Tapes for Helical-Scan Video Tape Reproducers for

Checking ReceivedMonitor Set-Up

RP 101-1986, Requirements for Recording American

National Standard Time and Control Code

Quad-

ruplex Video Tape Recorders

RP 103-1982, Care and Handling of Video Magnetic

Recording Tape (R1987)

RP 112-1983, Reference Carrier Frequencies, Pre-

Emphasis Characteristic and Audio and Control

Signals for li2-in Type H Helical-Scan Video Tape

Cassette Recording (R1988)

RP 113-1983. Supervisory Protocol for Digital Control

Interface

RP 114-1983, Dimensions of Photographic Control and

Data Record on 16-mm Motion-Picture Film

(R1989)

RP 115-1983, Dimensions of Photographic Control and

Data Record on 35-mm Motion-Picture Release

Prints (R1989)

RP 116-1990, Dimensions of Photographic Control and

Data Record

35-mm Motion-Picture Camera

Negatives

RP 117-1989, Dimensions of Magnetic Control and

Data Record on 8-mm Type

Motion-Picture Film

RP 118-1983, Dimensions of Photographic Control and

Data Record

8-mm Type

Motion-Picture Prints

(R1989)

RP 119-1984, Reference Carrier Frequencies, Pre-

Emphasis Characteristics and Audio and Control

Signals for 1/2-in Type G Helical-Scan Video Tape

Recording Cassette Systems

RP 120- 1983, Measurement of Intermodulation Distor-

tion in Motion-Picture Audio Systems (R1989)

RP 121-1988, Tape Dropout Specifications for 1-in

Types B and C Video Tape RecorderiReproducer

RP 125-1984, Bit-Parallel Digital Interface for Compo-

nent Video Signals

RP 127-1985, Specifications for Type

Audio Level

35-33

and Multifrequency Test Film for 35-mm Studio

Audio Reproducers, Magnetic Full-Coat Type

RP 132-1985, Storage of Edit Decision Lists on 8-in

Flexible Diskette Media (R1989)

RP 133-1986, Specifications for Medical Diagnostic

Imaging Test Pattern for Television Monitors and

Hard-Copy Recording Cameras

RP 134-1986, Polarity for Analog Audio Magnetic

Recording and Reproduction

RP 135-1986, Use of Binary User Groups in Motion-

Picture Time and Control Codes

RP 136-1986, Time and Control Codes for 24,25 or 30

Frame-Per-Second Motion-Picture Systems

RP 137-1986, Data Tracks on Low-Dispersion Magnet-

ic Coatings on 35-mm Motion-Picture Film

RP 138-1986, Control Message Architecture

RP 139- 1986, Tributary Interconnection

RP 140-1986, Position of Photographic Audio Record

for Routine Test Signals

RP 141-1986, Background Acoustic Noise Levels in

Theaters and Review Rooms

RP 142-1986, Stereo Audio Track Allocations and

Identification of Noise Reduction for Video Tape

Recording

RP 143-1986, Specifications for Type

Audio Level

and Multifrequency Test Film for 35-mm Striped

Four-Track Release Print Audio Reproducers

RP 144-1987, Basic System and Transport Geometry

Parameters for 1/2-in Type L Cassette

RP 145-1987, Color Monitor Colorimetry

RP 146-1987, Transfer of Edit Decision Lists

RP 147-1987, Audio Channel Assignments of Multi-

Channel Sub-Masters Used in Preparation for Two-

Track Masters for Transfer to Video

RP 148-1987, Relative Polarity of Stereo Audio Signals

RP 150-1988, Channel Assignments and Test Leader

for Magnetic Film Masters Intended for Transfer to

Video Media Having Stereo Audio

RP 154, Reference Signals for the Synchronization of

525-Line Video Equipment

RP 155-1990, Audio Levels and Indicators for Digital

Audio Records on Digital Television Tape Recorders

RP 156-1990, Bar Code Labeling for Type D-1 Com-

ponent and Type D-2 Composite Cassette Identifica-

tion

RP 157-1990, Key Signals

RP 158, Basic System and Transport Geometry Param-

RP 159, Vertical Interval Time Code and Longitudinal

RP 160, Three-Channel Parallel Analog Component

eters for U2-h Type M-2 Format

Time Code Relationship

High-Definition Video Interface

ENGINEERING GUIDELINES

5-1989, Projected Image Quality

70-mm, 35-

mm and 16-mm Motion-Picture Projection Systems

EG 6-1982, Use of 2-in Tape

CartridgeKassette

Spools for Quadruplex Video Tape Recorders

(R1987)

EG 7-1989, Audio Sync-Pulse for 8-mm Type

Cameras, Magnetic Audio Recorders and Rerecord-

ing Projectors

EG 8-1984, Specifications for Motion-Picture Camera

Equipment Used in Space Environment (R1989)

EG 9-1985, Audio Recording Reference Level for

Post-Production of Motion-Picture Related Materials

EG 10, Tape Transport Geometry Parameters for 19-

mm Type D-1 Cassette for Component Digital Video

Recording

EG 13-1986, Use of Audio Magnetic Test Films

EG 20, Tape Transport and Geometry Parameters for

19-mm Type D-2 Composite Format for Television

Digital Recording

EG 21, Nomenclature for Television Digital Recording,

19-mm Type D-1 Component and Type D-2 Com-

posite Format

EG 22, Description and Index of Documents for 19-mm

Type D-2 Composite Television Digital Recording

EG 23-1990, Transfer of Two-Channel Stereo Audio

from Audio Magnetic Film or Tape to Video Tape

EG 24, Video and Audio Alignment Tapes and

Procedures for 1-in Type C Helical-Scan Television

Analog Recorders

EG 25, Telecine Scanning for Film Transfer to Televi-

sion

26, Audio Channel Assignments for Digital Televi-

sion Tape Recorders with AES/EBU Digital Audio

Inputs

Video Disk Recordings-The use of optical video

disk recordings is increasing. The basic design of the

optical video disk system dates to the early 1980s, but

various factors, including the availability of low-cost

VCR machines, have slowed acceptance of the video

disk. The basic process for manufacturing the optical

video disk is to etch, in a continuous spiral on a master

disk, millions of “pits” that are width modulated by

the incoming video signal. This etching is accom-

plished by a modulated laser beam. Aluminized plastic

replicas of the master are then made in large volume and

are read (played back) by a low-power laser in the disk

player. The recorded and reproduced signal is analog.

The fundamental manufacturing process is similar in

many ways to that used to produce compact disk (CD)

recordings.

Both advantages and disadvantages are evident in the

video disk system. For example, a VCR provides the

user with the option of recording television programs

for later replay; the video disk is, up to now, entirely a

playback system. The recording situation may change as

the evolution of writeable and erasable optical disks

evolves, but it is not clear that costs can be sufficiently

reduced to assure success in the consumer market. Even

so,

the disk offers a series of advantages to the

professional user and to demanding consumers. The

system allows a high degree of random access; the laser

beam may be directed to reproduce any part of the disk,

to an accuracy of a single television frame, in less than a

second. In addition, the recording system is a wide-

bandwidth system and is capable of excellent picture

quality. Both of these useful attributes have made the

REFERENCE DATA FOR ENGINEERS

video disk popular for special applications such as the

distribution of recorded instructional and advertising

material by industrial users, as well as for educational

purposes in schools. It is also true that critical consum-

ers are turning to video disk recordings of motion

pictures for television display in their homes. Often the

picture quality obtained from the video disk is superior

that obtainable from VCR equipment. The standards

for video disk systems are written and published by the

IEC, through Technical Committee 60. The address of

the IEC is given in the section “International Standards

for Broadcasting” at the end of this chapter.

Selected Lists

Television

Standards

Listed below are two groups of industrial standards

that are useful in television engineering. The EIA list is

abbreviated; readers are encouraged to contact EIA

headquarters, at the address listed earlier in this chapter

the subsection “Standards and Specifications for

Recording Systems.

”

A comprehensive, up-to-date

listing is available.

EIA

Television Standards (Partial List)

TV Picture Tubes and Monitor Tubes

tem Recommended Practices

Identification Plan

TEP106-B, Worldwide Type Designation System for

TVSB5, Multichannel TV Sound System-BTSC Sys-

EIAIIS-6, Recommended Able Television Channel

IEB

Closed Circuit Television Definitions

IETNTS

Color Television Studio Picture Line Ampli-

fier Output Drawing

EIA-

170,

Electrical Performance Standards-Mono-

chrome Television Studio Facilities

EIA-3 12-A, Engineering Specification Outline for

Monochrome CCTV Camera Equipment

EIA-330, Electrical Performance Standards for Closed

Circuit Television Camera 525160 Interlaced 2:

EIA-343-A, Electrical Performance Standards for High

Resolution Monochrome Closed Circuit Television

Camera

EIA-375-A, Electrical Performance Standards for Di-

rect View Monochrome Closed Circuit Television

Monitors 525/60 Interlaced

EIA-403-A, Precision Coaxial Connectors for CASTV

Application

(75

Ohm)

EIA412-A, Electrical Performance Standards for Di-

rect View High Resolution Monochrome Closed

Circuit Television Monitors

EIA-420, Electrical Performance Standards for Mono-

chrome Closed Circuit Television Cameras 525/60

Random Interlace

EIA-439, Engineering Specification for Color CCTV

Camera Equipment

EIA-508, Electrical Performance Standards for Televi-

sion Broadcast Transmitters

EIA-563, Standard Baseband (AudioiVideo) Interface

Between NTSC Television Receiving Devices and

Peripheral Devices

Other

EIA

Standards:

EIA-232-D, Interface Between Data Terminal Equip-

ment and Data Circuit Terminating Equipment Em-

ploying Serial Binary Data Interchange

EIA-422-A, Electrical Characteristics of Balanced

Voltage Digital Interface Circuits

Note:

In addition to this selected list of EIA publiea-

tions, the association publishes an extensive range of

standards and other engineering publications concerned

with electronics and electronic engineering. A catalog

may be obtained from the address given above

the

subsection ‘‘Standards and Specifications for Record-

ing Systems.”

International Standards

for

Television Record-

ing-Most of the SMPTE and EIA documents listed

above have equivalent specifications in the publications

of international standardizing bodies. Video recording

standards are produced by the IEC Subcommittee 60B

and broadcast program exchange specifications by the

CCIR (published in CCIR Volume

1-Television

Broadcasting). A listing of relevant IEC and CCIR

standards is given later in this chapter. In addition, a set

of technical publications concerning video recording of

625-line PAL and SECAM color television signals is

available from the Technical Centre of the European

Broadcasting Union (EBU), whose address is given later

in this chapter.

International Standards

for

Television Film

Sys-

tems-Standards defining international specifications

for motion picture film are drafted by IS0 Technical

Committee 36 (TC 36). An abbreviated listing of these

documents is contained in the last part of this chapter.

In the USA,

IS0

standards may be obtained from

ANSI. In addition, the EBU publishes specifications for

motion picture film intended for television use by

members of the EBU, and the CCIR publishes specifi-

cations, in CCIR Volume

I-Television, for motion

picture films to be used for the international exchange of

television programs.

DIGITAL TELEVISION

SYSTEMS

Introduction

-The

Basics

Television is a medium for recording and transferring

images and sound from one point to another. The image

portion of the system is a “light-to-light” system,

gathering variations in light at the source via a pickup

device (such as a camera) and recreating those varia-

tions in light as a visual image via a display device such

as a cathode ray tube (CRT). The television system

transports the source information by scanning the image

and generating a continuous electronic signal that is a

representation of the light. Since the variations in light

at both the source and the display are continuous, the

television signal is inherently an analog signal, a signal

whose amplitude as a function of time represents the

BROADCASTING STANDARD§

visual content of the television image. This analog

signal can be transformed into a linear pulse-code-

modulation (PCM) digital representation of the image.

Digital forms of television have certain advantages

over the analog signal formats. An analog signal can be

degraded by the various transport media and processes.

These degradations include both linear and nonlinear

distortions and the introduction of noise. The degrada-

tions are both cumulative and difficult to separate from

the analog signal. Digital signals consist of a sequence

of two levels of information (logical

and logical

Os)

that can be sampled and restored as long as the

distortion and noise levels do not exceed certain thresh-

olds. Further, digital systems can be encoded with

redundant information

that even in the presence of

distortion and noise that exceeds the threshold of

separation between a

and a

the original information

can be restored. Once a television system has been

digitized, the image information is in the form of a

series of numbers which can be processed in a uniform

and consistent manner.

A digital television system (Fig. 19) consists of an

image source, a means such as a camera of converting

the image into an analog electronic signal

(EA),

a means

of transforming the analog signal into a digital signal

(analog-to-digital convertor, or A/D), some process

(P,)

which is applied to the digital signal, a means of

retransforming the resulting digital signal back to the

analog domain (digital-to-analog convertor, or D/A),

and a means such as a display of reconverting the analog

signal back into ‘‘light” for the benefit of the observer.

The digital process

(PD)

varies according to the

application. It can be a variable time delay used for

frame synchronization and time-base correction, a

video processor that corrects for luminance and chromi-

nance error, an image manipulator that permits digitally

generated effects and graphics to be added to the image,

a data-compression scheme

reduce the amount of

data, or simply a transmission path.

The

A/D

converter (Fig. 20) consists of four basic

components, a band-limiting, antialiasing filter (FA), a

sample-and-hold circuit

(S&H)

that samples the analog

signal, the quantizing unit

(Q)

that divides the range of

each analog signal sample into

distinct levels, and

finally an encoder (ENC) that places a specified code on

the output data lines (Do-D,) for each of the

levels.

For binary systems,

is a power of 2

29, where

is the number

bits) and the number

data lines is

related to the number of bits

1).

The

D/A

converter (Fig.

21)

consists

four basic

components, a digital input register (REG) in which the

bits of the word

be converted are stored for one time

period, a decoder

(DEC)

that converts the data lines

into

distinct analog levels, a resampling

(R,)

circuit

that corrects for distortions due to the digital sample-

and-hold process, and a band-limiting, restoration or

reconstruction filter

(b).

Resolution

The resolution of a television system is a measure of

its ability to delineate picture detail. For a number of

lines

normally alternate black and white lines, the

width of each line is

l/N

times the picture height. From

this definition, television resolution is expressed as

television lines per picture height (tvl/ph).

Based on early empirically derived data taken from

Engstrom* and others and later by Wheeler and

Loughren,? it was determined that vertical resolution

(R,)

could be expressed as

W,,

where

represented a

utilization factor that for 2:l interlaced CRT devices

was in the range

0.64

to 0.71. The factor

is influenced

by many variables including the shape of both the

gathering beam and the display beam. Work done on

progressive scan displays places an upper bound on

0.95. Assuming

0.66, the vertical resolution of the

NTSC-M system is given as

320

tvl/ph.

Horizontal resolution (Rh) is a function of the active

line period, the aspect ratio

(A)

of the image, and the

bandwidth of the signal

(f),

and

given as:

(l/A)P(f)/(F

where,

percent active period of the total line period,

frame rate,

number

scan lines.

For NTSC:

1/A

0.75

52.655163.555

0.828

29.97003

525

and

78.9

MHz.

digital system is limited by seven characteristics:

(f)

331.5 tvl/ph forf=

4.2

The image resolution and dynamic range of the

Reference

Fig.

19.

Digital television system.

35-36

REFERENCE

DATA

FOR ENGINEERS

p++~l+--~Dn

ANTIALIASING

SA:::&

QUANTIZING ENCODER

(

LEVEL

SELECTION)

F[LTER

Fig.

20.

AID

converter.

The resolution limitation

(Rh)

of the analog signal

The characteristics of the band-limiting, anti-

The frequency

(fs)

of the

AID

sampling pulse

The shape of the sampling pulse at the AID

converter

The number of bits

(B)

in the data word

(Do-D,)

which determines the number of levels

(Q)

that

can be defined

The shape of the resampling pulse

(fR)

at the D/A

converter

The characteristics of the band-limiting, restora-

tion filter

(b)

at the

D/A

converter.*

being converted, as noted above

aliasing filter (FA) in the

AID

converter

Sampling

and

Spectra

An analysis of the television signal spectrum shows

that the spectrum is composed of discrete frequency

components about harmonics of the line frequency

(f!)

and field rate

(fF)

(Fig.

22).

The analog signal

sampled by the periodic nature of the scanning struc-

ture, in that the scanning lines and the creation of image

frames have the effect of sampling the analog signal in

the temporal (T) and vertical

(V)

dimensions, respec-

tively. Whenever an analog signal of spectrum

sampled at intervals, such as with a rectangular pulse

train with a period of

(where

1/T

andfs is the

sampling frequency) as described in Fig.

23,

the

sampled signal has a spectrum equal to the original

spectrum plus a double sideband of width

repeated every& Hz, as shown in Fig.

24.

In the NTSC

system, most of the energy of the luminance signal is

concentrated in a set of sidebands of the line frequency.

Most of the energy of the chrominance signal is

concentrated in a set of sidebands of the color subcarrier

frequency. Since the color subcarrier is an integer

multiple

(455/2)

of the line frequency, these latter

sidebands are also related to the line frequency.? In the

NTSC system, the temporal sampling frequency

(fF)

59.94006

Hz, and the vertical sampling frequency is the

line rate

(fH),

15.734

kHz.

As shown in Fig.

20,

the first step in the analog-to-

digital conversion process is to sample the analog signal

with the digital sampling clock of frequency

fs.

This

produces a third shift in the frequency domain as shown

in Fig.

by creating a sampling structure in the

horizontal (H) dimension.

A close inspection of the process in both the temporal

and frequency domains indicates that the sampling

process must conform

certain criteria. If the maxi-

mum frequency contained within the analog signal ish

and the frequency of the sampling pulse is

fs,

then

must be greater than

fA.

Fig.

shows the result of

sampling the spectra with a sampling frequency greater

than

fA.

When an analog signal is sampled at a rate

at least twice its highest frequency component, the

sampling is said to meet the

Nyquist

criterion.

Fig.

shows the result of sampling the spectra with a sampling

frequency less than

fA.

It is clear that if the

frequency of the sampling pulse is less than

fA,

the

spectra of the original baseband signal and the spectra

of the sidebands at the multiples of the sampling

frequency of the resultant Fourier transform overlap as

shown by the shaded area in Fig.

25.

This makes an

accurate restoration of the original baseband signal

extremely difficult, as the sidebands would appear to

have component information that does not really ex-

ist.

The erroneous signal content is termed

aliasing.

Fig.

shows an example of a sub-Nyquist-sampled,

analog baseband signal

a single frequency for illus-

trative purposes. In this instance, the reconstructed signal

Reference

EA'

DECODER RECONSTRUCTION

INPUT

Fig.

21.

DIA

converter.

BROADCASTING STANDARDS

35-37

SPECTRA

DUE

TO SCENE MOTION

Sampling

frome

rote

(fF)

Sompllng

line

rate

(fHJ.

Fig.

22.

Sampling spectra.

would have two frequency components where the origi-

nal signal consisted of a single frequency component.

low-pass filter is inserted at the first stage of the

A/D

converter to limit the frequency content

the

analog signal to within the Nyquist criteria. This filter is

often referred to as an

antialiasing

filter.

In television systems, the sampling clocks selected

not only meet the Nyquist criteria but also are generally

multiples of the horizontal line rate

(fH)

of the system.

sampling clock which is a multiple of

produces a

sampling structure which is orthogonal as shown in

Fig.

21.

Orthogonal structures are line, field, and frame

repetitive, meaning that the samples “line up.” Such

structures simplify the process of digital filtering.

Further, it is also desirable for the sampling-pulse

frequency of encoded systems such as NTSC to be

multiples of the color subcarrier. In the NTSC system, a

sampling clock that is

4f,.

or four times the color

subcarrier, is also a harmonic of the line rate and,

therefore, orthogonal. This simplifies the separation

luminance and color from an encoded signal.

picture

sample

(X),

or pel, on one line has a luminance

(Y)

and

chroma

(+C)

component

C).

the picture

element in the next line

the same, it will have the

same luminance

(Y)

value, but the chroma value will be

180”

out of phase

One-half the sum of the

two equals

and one-half the difference of the two

equals

;

[(Y

C)]

;

[(Y

C)]

The television systems of the broadcast 525-line and

625-line standards

are

all derived from a relationship to

analog signal

___

110

101

100

011

010

001

000

QLEVELS

3-BIT

(NOMINAL CODING

PULSE DURATION VALUE

QUANTIZING)

SAMPLING

POINTS

Fig.

23.

Sampling

analog signal.

35-38

REFERENCE

DATA

FOR ENGINEERS

Fig,

25.

Sub-Nyquist sampling

(fs

2fa).

Fig.

24.

Sampling-Nyquist criterion

(fs

2fA).

4.5 MHz as shown in Fig. 28, and therefore, the line,

field, frame, and sampling frequencies have integer

submultiple relationships. This also helps when samples

based on one sampling structure must be translated

(standards converted) into an alternative sampling

structure. The sampling structures for the proposed

advanced television (ATV) systems are also orthogonal.

Quantizing

and

Dynamic Range

The analog signal having been separated into discrete

samples, the second step is to quantize the samples.

Quantizing a set of values (or samples)

simply the act

of describing each member of the set of values as a

multiple of a basic unit, dividing the range of values into

quantizing levels. The range of values which can be

represented is

to Q- 1. In binary systems,

2’,

where

equals the number of bits. A segment of an

analog signal waveform

shown in Fig. 23 with the

periodic sampling signal and an eight-level quantizer

Z3) superimposed. If we assume that each level

represents 0.125 V, then the range of the input signal

that can be accurately represented is

to 0.875

times 0.125 V). The levels need not be uniformally

quantized (equally spaced) to provide a linear sampling

of the analog signal, but in most systems, the levels are

uniformally quantized.

The sampled analog signal is discrete in time but

remains continuous in amplitude. However, the quan-

tizing process assigns all analog values within a specific

quantizing interval the same quantizing value, the

nominal value for that interval. This produces a quan-

tizing error in the restored, reconverted analog signal;

this error

known as

quantizing

noise.

As shown in

Fig. 23, the quantizing error can not exceed +Q/2.

The theoretical maximum peak-to-peak signal-to-

quantization-noise ratio (SNR), or dynamic range, of

the quantized signal is determined by the number

levels (Q) selected, but is also influenced by the shape

of the sampling pulse and the relationship between the

maximum bandwidth of the signal,&, and the sampling

frequency,&. The analog signal contains noise, and, as

a very over-simplified explanation, the sampling proc-

ess tends to “average” the noise in a sample. The

equation for SNR of a quantized signal is:

SNR

20 log

and since

can be replaced in binary systems by 2’,

SNR

log 2’

log

6.02

In uniformally quantized, pulse-coded modulation

(PCM) systems,

has been derived as:

10 log [&1(2

&)I

where

is the component due to the application of

uniformally quantized sampling and is given as

log

12. Therefore,??

10.79

log [fs/(2

fA]

For the example of a 4.2-MHz NTSC signal, sampled at

four times the color subcarrier in a ten-bit system

1024),

SNR

10.79

10 log (14.318/8.4)

6.02

73.30

Composite

and

Component

Signal Coding

The transmitted television signal format in the United

States is the NTSC-M format, a composite signal

consisting

the luminance

(Y)

information, the chro-

minance information as two signals

and Q) quadra-

ture modulated onto a color subcarrier, and the synchro-

Fig.

26.

Sub-Nyquist

sampling-single frequency.

Reference

10.

Line

41, Field

Line

41, Field 2

Line

42, Field

Line

42,

Field

xxxxxx

Fig.

27.

Section

NTSC

sampling

array

showing orthogonal

arrangement

samples.

33.750

kHz

1125/60/2:1

3/286

47.202

WHZ

787.5/59.94/1:

31.468

kH2

1050/59.94/2:1

2/1050

455/2

14.318

MHz

CUR.

Ree.

601

F-

27.000

MHz

CCR.

Re=.

601

INERFACE

CLOCK

1573

74.25

MHZ

2376

2304

SAMPIING

SAMPLING

1/2

37.125

MHz

360

MHz

SAMPLING

Fig. 28. Frequency relationships in

NTSC,

PAL,

CCIR-601,

and

ATV

systems (references

and

9).

35-40

REFERENCE DATA FOR ENGINEERS

nization pulses. This signal is also the format used in

many instances in television production facilities for

distribution and recording of the television signal. The

analog television signal originates in the camera

tricolor signal representing the red

(R),

green (G), and

blue

(B)

components of the signal. The R,

and

components are matrixed to form the

and Q signals

as described in Fig.

19 and Table

The analog

television signal also appears in its component form in

some portions of the production facility, such as in the

production of graphics or special effects in order to

avoid the limitations in both luminance and chromi-

nance signal bandwidth and cross-color and cross-

luminance distortions inherent in the NTSC system and

the signal degradation caused by multiple decoding of

the composite signal back into its components and the

re-encoding to the composite form.

The digital television signal may be implemented in

either the composite or component representation

the

television signal. The composite representation is based

on the sampling of the NTSC encoded signal and is

described in the section “Composite Encoded Signals:

SMPTE

244

(NTSC and PAL).” The component repre-

sentation accepts separate baseband tricolor stimulus

signals and individually samples and quantizes them.

The component representation of the video signal can

be in one of many tristimulus formats. The most

common formats are

(1)

a luminance signal,

and two

color-difference signals,

ks(B

and

kR(R

CR;

and (2) the baseband

G, and

signals. The

component representations are discussed in the section

“Component Coding of Signals: SMPTE 125 and

CCIR 601

.”

Bit-Parallel and Bit-Serial

Interfaces

The composite and component signal format inter-

faces are both electrically and mechanically similar in

both the parallel data format and serial data format. The

parallel interface consists of a unidirectional, eleven-

pair interconnection between a transmitting equipment

and a receiving equipment. Video data, timing refer-

ence information, and ancillary signals are time multi-

plexed and transferred on ten data pairs in NRZ form.

An eleventh pair provides

synchronous clock. The

serial interface consists of a unidirectional, bit-serial

single interconnection between a transmitting equip-

ment and a receiving equipment.

The data signals are in the form of binary information

coded in 8- or 10-bit words. These signals are:

Video data

Timing reference codes

Ancillary data, including audio services

Identification codes such as video index

information

The signaling sense of the voltage appearing across the

interconnection cable is positive binary and defined as

follows (refer

Fig. 29):

The A terminal of the transmitter shall be negative

with respect to the

terminal for a binary

(LOW or L or OFF) state.

2. The A terminal of the transmitter shall be positive

with respect to the

terminal for a binary

(HIGH or H or ON) state.

In these interfaces, all digital-signal time intervals

are specified at the half-amplitude points. All

transitions are specified between the

20%

and

80% amplitude points.

In the parallel signal interface, the data lines are

designated DATA

through DATA 9. The group

ten signals is identified by placing parentheses

around the range of subscripts included, as DATA

(0-9). When 8-bit signals are conveyed by the

interface, DATA (2-9) are used and DATA (0-1)

are set

zero. DATA 9 is always the most

significant bit.

Composite Encoded Signals:

SMPTE

244

(NTSC

and

PAL)

The Society of Motion Picture and Television Engi-

neers (SMPTE) developed a common composite inter-

face that serves the needs of both 525-line/59.94-Hz

NTSC systems and 625-line/50-Hz PAL systems. The

characteristics of the interface are summarized for the

525-line case in Table 8.:

Reference

12.

Reference 13.

TABLE

NTSC-M COLOR TELEVISION

SYSTEM*

Parameter Equation

Luminance

signal

Y’

0.299

R‘

0.587

G‘

0.114

B‘

Color-difference signals

I’

-0.27

(R’

Y’)

0.74

(B’

Y’)

Q‘

0.41

(R’

Y’)

0.48

(B’

Y’)

M’

Y‘

sin

(2?rf,,

33”)

where

R’,

G’,

B’

are

the

gamma-

precorrected signals.

Composite

color

signal

cos

(2?rf,,

33”)

Reference 11.

BROADCASTING STANDARDS

TABLE

ENCODING PARAMETERS

FOR

NTSC COMPOSlTE TELEVISION"

35-41

Parameter

Coded signal

Samples per total line

Sampling structure

Sampling frequency

Serial interface data rate

Form of coding

Number

samples per active line

Correspondence between video

signal

levels

and

quantization

levels

Alignment

Reference 14.

Component Coding

Signals:

SMPTE

125 and CCIR

601

The Society of Motion Picture and Television Engi-

neers (SMPTE) and the European Broadcasting Union

(EBU), working jointly, developed a common compo-

nent interface that serves the needs of both 525-line/

59.94-Hz systems and 625-line/50-Hz systems. The

interface is documented in CCIR (International Radio

Consultative Committee) Recommendation

and in

SMPTE 125M. The characteristics of the interface are

summarized in Tables 9 and

10.

The

CB,

and

signals are transmitted at the

4:2:2 level equivalent of the CCIR document

601

digital

hierarchy for television signals, with a nominal sam-

pling frequency of 13.5 MHz for the luminance signal

and 6.75 MHz for each of the color-difference signals.

Because of the existence of both 8-bit and 10-bit

equipment, all synchronizing signals (EAV, SAV, ANC)

must be detected by reference to the

most significant

bits only.

the parallel data format, data is transmitted across

the interface on ten data pairs: DATA

through DATA

9. DATA 9 is the most significant bit (MSB). For the

10-bit system,

1016

of the 1024 levels [digital levels 4

(004,) through 1019 (3FBH)]

the ten-bit word are

Composite NTSC-M

Composite NTSC

910

Orthogonal (line, field,

and

picture

repetitive)

4 timesf,

14.318 MHz

143.18 Mbitsls

Uniformly quantized PCM, 8

bits

per sample

768

8-bit samples: The

tip

the

synchronization pulse (-40

IRE)

corresponding to level

(04H), the

blanking level corresponding to level

(3CH),

and

the

peak

white level (+lo0

IRE)

corresponding to level 232 (C8,)

10-bit systems: The tip

the

synchronization pulse corresponding

level

(OIOH), blanking level

corresponding to level 240

(OFOH)

and

the peak white level corresponding

level

800

(320")

The sample

interval

line 10,

field

color frame

axis

123")

sample.

used to express quantized values. For the 8-bit system,

data values 1 through 254 (OIH-FE,) may be used to

express quantized signal values.

The digital code words that describe the video signal

are conveyed as a 27-megaword/second multiplex in the

following order:

CB?

[yl,

. .

where the three words CB,

and CR refer to the

co-sited samples; the following

[Y]

is an isolated

luminance-only sample. The CR,

samples are

co-sited with the odd (Ist, 3rd, 5th,

. .

)

samples

each line, as shown

Fig. 30. The first video data

word in the active line period is

Synchronization and Blanking

Interval Considerations

The digital interfaces provide for the transmission of

synchronization and ancillary data that may be multi-

plexed into the data stream during video blanking

intervals.

each of the component systems, four

specific sample words or interface clock intervals are

reserved for the end-of-active-video

(EAV)

timing refer-

ence, and four specific sample words are reserved for