The document discusses analog television transmission and reception. It covers topics such as: - TV broadcast channel allocation standards and frequencies - Analog TV signal parameters including video scanning, signal bandwidths, and modulation techniques - Components of analog TV transmitters and receivers such as tuners, amplifiers, detectors and more - Color TV fundamentals including color encoding and transmission systems like PAL, NTSC, and SECAM - A comparison of the features of different analog color TV transmission standards

1. Audio Video
Engineering
BY:-Yogesh

2. ANALOG & DIGITAL T.V. TRANSMISSION & RECEPTION:
• T.V. BROADCAST CHANNELS
• CCIR-B STANDARD
• VESTIGIAL SIDE BAND TECHNIQUE
• INTERLACE SCANNING
•COMPOSITE VIDEO SIGNAL
•COMPATIBILITY REQUIREMENT
•COLOUR TV FUNDAMENTALS.
• FREQUENCY INTERLEAVING
• PAL, NTSC, SECAM SYSTEMS
• ANALOG T.V. TRANSMITTERS
• T.V.RECEPTION

3. TELEVISION BROADCAST CHANNELS
For television broadcasting channels have been assigned in the VHF
and UHF range.
The allocated frequencies are:
Lower VHF range band I - 41…………68 MHz.
Upper VHF range band III - 174………230MHz.
UHF range band IV - 470………582MHz.
UHF range band V - 606………790MHz.
(Band II , 88 to 108 MHz is allocated for FM broadcasting )
The channel allocation in band I and III are given below. There are
four channels in band I, of which channel I is no longer used for T. V.
broadcasting.

4. TELEVISION CHANNEL ALLOCATION CCIR:
Band range Channel
MHz
Frequency
Range
Picture
carrier MHz
Sound
carrier MHz
I
(41-68MHz)
1
2
3
4
41-47
47-54
54-61
61-68
Not in use
48.25
55.25
62.25
53.75
60.75
67.75
III
(174-
223MHz)
5
6
7
8
9
10
174-181
181-188
188-195
195-203
202-209
209-216
175.25
182.25
189.25
169.25
203.25
210.25
180.75
187.75
194.75
201.75
208.75
215.75
Additional
channel
11
12
216.23
223.23
217.25
224.25
222.75
229.75

5.  CCIR-B Standard

1) Video characteristics:
 Number of lines/picture-625
 Interlace ratio-2:1
 Scanning sequence for lines-left to right
 Scanning sequence for field-Top to bottom
 Field freq-50 fields/sec
 Line freq-15625 Hz
 Aspect ratio-4:3
 Video bandwidth-5 MHz
 Vertical resolution-0.7 x (625-40)=409lines.
 Horizontal resolution =[410 x (4/3)]=546
alternate Black & white lines.

6. 2) Composite video signal:
• Line period-64μs
• Line blanking period-12μs
• Front porch-1.5μs
• Back porch-5.8μs
• Sync pulse period-4.7μs
• Post and pre equalizing pulse-160μs
• Vertical blanking pulse-1280μs
• Field period-20ms
• Sync level-100%
• Blanking level-75%
• White level-10%

7. 3) Radio freq. Characteristics:
• Channel B.W.-7MHz
• Sound to Picture carrier difference-5.5MHz
• Picture modulation-AM VSB
• Sound modulation-FM.
• Carrier deviation-±50KHz.
• Pre- emphasis-50μs
• Colour sub carrier burst-4.43 MHz.
• Space wave (Line of sight) Propagation.
• Horizontal Polarization.

11. COMPATIBILITY
COLOUR SIGNAL IS INSERTED WITHIN 7MHz CHANNEL B.W.
FOR PAL SYSTEM, 6MHz FOR NTSC & 8MHz FOR SECAM
COLOUR SIGNALS ARE COMPATIBLE WITH BLACK & WHITE
SYSTEM.
COLOUR TRANSMISSION SYSTEM PRODUCES A NORMAL BLACK
& WHITE PICTURE ON MONOCHROME RECEIVER.
A NORMAL BLACK & WHITE TRANSMISSION SHOULD PRODUCE
A BLACK & WHITE PICTURE ON A COLOUR TV SCREEN.
COLOUR TV SYSTEM MUST HAVE SAME VIDEO B.W.
IT MUST USE SAME LINE & FRAME SYNCHRONISING PULSES.

12. COLOUR TV FUNDAMENTALS
GRASSMAN’S LAW
LUMINANCE OR BRIGHTNESS, HUE & SATURATION
CHROMACITY DIAGRAM
MIXING OF COLOUR
1. ADDITIVE MIXING
2. SUBTRACTIVE MIXING
COLOUR DIFFERENCE

17. ANALOG TELEVISION
RECEIVER
• YAGI ANTENNA
• RF TUNER
• VIDEO IF AMPLIER
• VIDEO DETECTOR
• SOUND PROCESSING SECTION
• LUMINANCE CHANNEL
• SAW FILTER
• PAL DEMATRIX
• VIDEO DRIVE SECTION
• DEFLECTION SECTION
• EHT SECTION
• HORIZANTAL OSCILLATOR
• VERTICAL OSCILLATOR
• SMPS

18.  RF TUNER:
It selects the channel to be received by switching pre-tuned circuits in the RF
stage in the oscillator.
It matches the impedance of the line at its i/p and amplifies it to maintain a
good signal to noise ratio.
It converts the RF into IF by mixing with the local oscillator frequency to feed
it to the VIF amplifier.
MULTISTAGE VIF AMPLIFIER:
Used in conjunction with a surface acoustic wave(SAW) filter and a preamp to
obtain a high controlled gain (upto 80db).
For VSB reception, it amplifies picture if (38.9MHz), COLOUR SUBCARRIER
IF(34.47mhz) at 50% and SOUND IF(33.4 MHz) AT 5 – 10% of the peak
amplification between the 35-38MHz range.
The last stage feeds into a video detector
VIDEO DETECTOR
It extracts the video signal from the modulated IF signal.A diode detector is
commonly used to demodulate the amplitude modulated video if signal by
rectification.
Due to non linearities in the simple diode detectors,synchronous
demodulators or balanced multipliers are used in modern receivers.

19.  SYNCHRONOUS VIDEO IF DETECTION
It works on the sampling principle to overcome nonlinearities and harmonics.The
amplitude modulation is detected at the sampling intervals by limiting the carrier
and selecting the pure carrier by tuned resonant ckts.The video modulated signal
carrier is sampled by a pure unmodulated carrier of exactly the same
frequency.The phase relation between the reference carrier and modulated signal
are vital for detection
 SOUND SEPERATION AND PROCESSING
The SOUND IF signal at 33.4MHz is taken off at the output of the second VIDEO
I.F. Stage by means of a tuned circuit which feeds into a diode detector. The VIF
and SIF are heterodyned in this detector to produce different frequency as the
intercarrier SIF at 5.5MHz.The composite colour video signal is amplified and
passed on to the luminance channel for amplification of the monochrome Y
signal,and to the chroma section for decoding and further processing of the
chrominance signal.
 LUMINANCE CHANNEL
It provides normal video amplification for monochrome signals with facility of
contrast adjustment by the amplifier gain control and brightness adjustment by
suitable bias variation of picture tube.It has to incorporate a delay line to keep the
luminance signal in step with the chrominance signal.A notch filter is used to
block the colour sub carrier(4.43MHz) which would otherwise cause dot pattern
interference.

20. .
 SYNCHRONOUS DETECTION
The U & V signals from the pal dematrix are applied to two synchronous
demodulators ,it passes only the signals that are in phase with the two quadrature
phased with the two quadrature phased reference subcarrier signals . The colour
burst signal required to synchronise the locally generated sub carriers separated
from the CVS.

21.  VIDEO DRIVE SECTION:
The U & V signals obtained at the output of the synchronous detectors are
amplified by the relative gain factor of 1.140 for V channel to get back the (R-Y),and
2.028 for U channel to (B-Y).
The (G-Y) is obtained by matrixing (R-Y) &(B-Y).The three colours reclamped to
get the maximum black and the luminance.
 DEFLECTION CIRCUITS:
Sync separation synchronization of the horizontal and the vertical oscillator that
drive the horizontal and vertical coils ,generation of the EHT the focus anode
and other auxiliary voltages and blanking during fly back are provided by
deflection ckts
Degaussing coils are provided for removing stay colouring effects on the screen
caused by stray magnetic field.

22. FREQUENCIES
VIF-38.9MHz
SIF-33.4MHz
COLOUR SUB-CARRIER-4.43MHz
INTERCARRIER SIF-5.5MHz

28. Comparision between NTSC , SECAM & PAL transmission systems:
NTSC SECAM PAL
•Horizontal line
•Field frequency
•Bandwidth
•SC_PC difference
•Colour signal
•Colour signal
Modulation
•Principle of
operation
•Phase error
•Colour sub carrier
burst
•Application
525
50 Hz/60Hz
6-7MHz
5.5MHZ
I & Q
I=0.74(R-Y)-0.27(B-Y)
Q=0.48(R-Y)+0.41(B-Y)
QAM
Simple
Subjected to phase error
3.579MHz
USA
625
50Hz
7-8MHZ
6.5MHz
DR & DB
DR=-1.9(R-Y)
DB=-1.5(B-Y)
FM
Complicated
Phase error is
minimum
4.4MHz,
4.25MHz
FRANCE
625
50Hz
6-7MHZ
5.5MHz
U & V
U=0.493(B-Y)
V=0.877(R-Y)
QAM
Complicated
No phase error
4.43MHz
INDIA,
AUSTRALIA
G-Y signal is not transmitted.
G-Y= -0.51(R-Y)-0.186(B-Y)
(R-Y) & (B-Y) signals are transmitted. (G-Y) signal is derived from these two signals.

29. Principles of colour T.V. Transmitter
T.V Transmission requirements:
•T.V uses line of sight transmission.(Space Wave)
•The height of the antenna should be as high as possible.
•Omni directional antennas should be used.
•The audio & Video powers should be adjusted properly.
•The adjacent channel stations should be as apart as possible.

30. Design Principles of T.V. Transmitters:
• Video signals amplitude modulated.
Amplitude Modulation
Low Level High Level
• High Level Modulation:
The signal & carrier both are amplified first to the power level
required for transmission .The modulating signal then modulates the carrier.
Thus the modulator operates at high power level.
• Low Level Modulation:
The modulation takes place at low voltage levels of modulating
& carrier signal.The vestigial side band filter is located after modulator. Hence
VSB filter operates at low power level.

31. VEDIO
PROCESSING
UNIT
DIODE
BRIDGE
MODULATOR
DELAY
EQUALISER
LINEAR
AMPLIFIER
VSB
FILTER
VIDEO UP
CONVERTER
PA
‘X’ TAL
OSC
FREQUENCY
MULTIPLIER
‘X’ TAL
OSC
AUDIO
PROCESSING
UNIT
MODULATED
OSCILLATOR
AUDIO UP
CONVERTER
LINEAR
AMPLIFIER
PA
LPF
PHASE
DETECTER
‘X’TAL
OSC
DIPLEXER
AFC LOOP 33.4MHZ
33.4MHZ
SC
38.9MHZ
(SC+33.4MHZ)
(PC+38.9MHZ)
PC38.9MHZ
TO
ANTENNA
FIG: BLOCK DIAGRAM OF IF MODULATED TV TRANSMITTER
VIDEO
AUDIO

32. I/P AMP
SYNC
GENERATER
EQUILISER
PHASE
COMPENSATOR
V F
AMPLIFIER
MODULATING
AMPILFIER
‘X’TAL
M.O
MULTIPLEXER
*2*2*3*3
AMPILFIER
P.A
DRIVER
P.A
DRIVER
VIDEO
O/P
AMPLIFIER
VSBF &
DIPLEXER
PRE-
AMPLIFIER
FM
MODULATOR
MULTIPLEXER
*2*2*3*3
AMPLIFIER
P.A
DRIVER
PA
AFC
‘X’ TAL
OSC
500VA
350W
2KW
10KW
(FILTER
PLEXER)
TO ANTENNA
SYSTEM
VF AF
MONITOR
RECEIVIER
VIDEO
AUDIO
FIG: BLOCK DIAGRAM OF A 10KW VHF TRANSMITTER
USING

33. SR
NO.
PARAMETERS LOW LEVEL
MODULATION
HIGH LEVEL
MODULATION
1 POINT AT
WHICH
MODULATION
TAKES PLACE
MODULATION TAKES
PLACE IN THE INITIAL
STAGES OF
AMPLIFICATION
MODULATION TAKES
PLACE IN THE FINAL
STAGE OF
AMPLIFICATION.
2 POWER
LEVEL
MODULATION
CIRCUITARY HAS TO
HANDLE LOW POWER
MODULATION
CIRCUITARY HAS TO
HANDLE HIGH POWER
3 COMPLEXITY MODULATION
CIRCUITARY IS SIMPLE
AS IT HAS TO HANDLE
LOW POWER
MODULATION
CIRCUITARY IS QUITE
COMPLEX AS IT HAS TO
HANDLE HIGH POWER.
4 PRIME
FACTOR IN
DESIGN
SIMPLICITY IS THE
PRIME REQUIRMENT
PRIME REQUIREMENT IS
HIGH EFFICIENY & LOW
DISTORTION.
5 AMPLIFIER
USED
LINEAR AMPLIFIER SUCH
AS CLASS A AMPLIFIER IS
USED
HIGH EFFICIENCY CLASS C
AMPLIFIER IS USED
6 EFFICIENCY EFFICIENCY IS LOW EFFICIENCY IS HIGH
DIFFERENCE BETWEEN LOW LEVEL & HIGHDIFFERENCE BETWEEN LOW LEVEL & HIGH
LEVEL MODULATIONLEVEL MODULATION

37. THE END
THANK YOU !!