1. COURSE: AUDIO VIDEO ENGINNERING COURSE CODE: 17537
CHAPTER : 4. TV Transmitter and Receiver
Marks: 20 Marks.
Contents:
Audio and Video signal transmission using AM and FM modulation.
Positive and Negative modulation
Introduction to TV camera tube (Vidicon, Plumbicon, Solid State camera based on CCD.)
Color Picture tube (PIL, Delta gun picture tube, Trinitron)
Block diagram of Colour TV transmitter.
Block Diagram of color TV receiver (PAL D type)
20 September September 2018

2. Audio and Video signal transmission using AM and FM modulation.
AM is preferred for picture because the following reasons,
The distortion which arises due to interference between multiple signals is more objectionable in FM than AM because the frequency of the FM signal continuously changes.
Hence, hardly any steady picture is produced.
Alternatively if AM were used, the multiple signal paths can at most produce a ghost image which is steady.
In addition to this, circuit complexity and bandwidth requirements are much less in AM than FM.
TV Transmitter and Receiver
20 September September 2018

3. FM is preferred for sound because the following reasons,
The bandwidth assigned to the FM sound signal is about 200 kHz of which not more than 100 kHz is occupied by sidebands of significant amplitude.
The latter figure is only 1.4 per cent of the total channel bandwidth of 7 MHz. Thus, without encroaching much, in a relative sense, on the available band space for television transmission all the advantages of FM can be availed.
TV Transmitter and Receiver
20 September September 2018

4. SUBJECT: AUDIO VIDEO ENGINNERING SUBJECT CODE: 17537
CHAPTER : 4. TV Transmitter and Receiver
Marks: 20 Marks.
Contents:
Audio and Video signal transmission using AM and FM modulation.
Positive and Negative modulation
Introduction to TV camera tube (Vidicon, Plumbicon, Solid State camera based on CCD.)
Color Picture tube (PIL, Delta gun picture tube, Trinitron)
Block diagram of Colour TV transmitter.
Block Diagram of color TV receiver (PAL D type)
20 September September 2018

5. Positive and Negative modulation
Positive Modulation
Negative Modulation 1.
When increase in brightness of that picture results in an increase of the amplitude of modulated envelope.it is called positive modulation.
When increase in brightness reduces amplitude of the modulated envelope, it is called negative modulation. 2.
White level of video signal corresponds to 100% total magnitude.
White level of video signal correspondence to 12.5% of the total amplitude. 3.
Waveforms (next slide) 4.
Noise pulses do not effect synchronization but cause white spot in the picture
Noise pulses are seen as less annoying black spot. 5.
More power is required with less efficiency
If peak power available from transmitter is considered them less power is required for more efficiency. 6.
Black level of video signal correspondence to 25% of total magnitude.
Blanking level starts at 75%
TV Transmitter and Receiver
20 September September 2018

6. TV Transmitter and Receiver
20 September September 2018

7. Merits & Demerits of Negative modulation
Lesser noise interference on picture signal.
Possible to obtain larger peak power output.
Less picture signal distortion.
Easy to develop true AGC voltage.
More efficient operation.
More power available from the transmitter
Saving in transmission power
Demerits:
The synchronization of the receiver is affected by spurious random pulses produced due to the effect of noise.
The loss of horizontal and vertical synchronization may cause diagonal or vertical rolling of picture.
TV Transmitter and Receiver
20 September September 2018

8. SUBJECT: AUDIO VIDEO ENGINNERING SUBJECT CODE: 17537
CHAPTER : 4. TV Transmitter and Receiver
Marks: 20 Marks.
Contents:
Audio and Video signal transmission using AM and FM modulation.
Positive and Negative modulation
Introduction to TV camera tube (Vidicon, Plumbicon, Solid State camera based on CCD.)
Color Picture tube (PIL, Delta gun picture tube, Trinitron)
Block diagram of Colour TV transmitter.
Block Diagram of color TV receiver (PAL D type)
20 September September 2018

9. photoemission & photoconductivity. Photo electric effect:
The two photoelectric effects used for converting variations of light intensity into electrical variations are
photoemission
&
photoconductivity.
TV Transmitter and Receiver
20 September September 2018

10. TV Transmitter and Receiver
20 September September 2018

11. Solid State camera based on CCD. Image orthicon
TV camera tube
Vidicon
Plumbicon
Solid State camera based on CCD.
Image orthicon
TV Transmitter and Receiver
20 September September 2018

12. Based on PHOTOCONDUCTIVITY
Vidicon :
Based on PHOTOCONDUCTIVITY
TV Transmitter and Receiver
20 September September 2018

13. TV Transmitter and Receiver
20 September September 2018

14. Based on PHOTOCONDUCTIVITY
Plumbicon:
Based on PHOTOCONDUCTIVITY
TV Transmitter and Receiver
20 September September 2018

15. TV Transmitter and Receiver
20 September September 2018

16. It is similar to vidicon tube except small change in target plate
lower image lag.
It has fast response and produce high quality pictures at low light level.
It has small size and light weight and has low power operating characteristics .
It is similar to vidicon tube except small change in target plate
TV Transmitter and Receiver
20 September September 2018

17. Solid State camera based on CCD.
TV Transmitter and Receiver
20 September September 2018

18. SUBJECT: AUDIO VIDEO ENGINNERING SUBJECT CODE: 17537
CHAPTER : 4. TV Transmitter and Receiver
Marks: 20 Marks.
Contents:
Audio and Video signal transmission using AM and FM modulation.
Positive and Negative modulation
Introduction to TV camera tube (Vidicon, Plumbicon, Solid State camera based on CCD.)
Color Picture tube (PIL, Delta gun picture tube, Trinitron)
Block diagram of Colour TV transmitter.
Block Diagram of color TV receiver (PAL D type)
20 September September 2018

19. PIL Delta gun Trinitron Colour Picture tubes
TV Transmitter and Receiver
20 September September 2018

20. Delta gun: TV Transmitter and Receiver
20 September September 2018

21. DRAWBACKS OF DELTA GUN PICTURE TUBE:
Convergence is difficult and involves considerable circuit complexity and service adjustments. In most delta-gun tubes, four static convergence magnets and a dynamic convergence assembly are employed.
The focus cannot be sharp over the entire screen because the focus and convergence planes cannot remain coincident for the three beams which emanate from guns positioned at 120° with respect to each other around the tube axis.
The electron transparency of the mask is very low since it intercepts over 80 percent of the beam currents.
TV Transmitter and Receiver
20 September September 2018

22. PIL (Precision-in-line):
TV Transmitter and Receiver
20 September September 2018

23. ADVANTAGES OF PIL:
Due to vertical slots, electron transparency is about 50% which is much more than 20%. Hence its efficiency is better.
Vertical convergence is not needed & hence convergence adjustment is less than required in delta gun.
Focus is sharp all though the screen as the guns are in the same plane.
TV Transmitter and Receiver
20 September September 2018

24. DRAWBACK
Due to nonuniformity of the deflection field all the beams are not deflected by the same amount. As shown in Fig. the central beam (green) deflects by a smaller amount as compared to the other two beams.
For a different nonuniformity of the deflection field, the effect could be just opposite producing too large a displacement of the central beam.
Such a distortion is known as coma and results in misconvergence of the beams.
TV Transmitter and Receiver
20 September September 2018

25. Trinitron: TV Transmitter and Receiver
20 September September 2018

26. ADVANTAGES OF TRINITRON:
Improved Vertical resolution
Greater transparency for the electron beam, being about 80% against 20% for delta gun & 50% for PIL. Consequently efficiency is high.
Controls are only 6 against 12 each in delta gun & PIL.
Sharper focus & brighter picture.
No problem of convergence adjustment.
TV Transmitter and Receiver
20 September September 2018

27. TV Transmitter and Receiver
20 September September 2018

28. SUBJECT: AUDIO VIDEO ENGINNERING SUBJECT CODE: 17537
CHAPTER : 4. TV Transmitter and Receiver
Marks: 20 Marks.
Contents:
Audio and Video signal transmission using AM and FM modulation.
Positive and Negative modulation
Introduction to TV camera tube (Vidicon, Plumbicon, Solid State camera based on CCD.)
Color Picture tube (PIL, Delta gun picture tube, Trinitron)
Block diagram of Colour TV transmitter.
Block Diagram of color TV receiver (PAL D type)
20 September September 2018

29. Block diagram of Colour TV transmitter.
Colour Camera
Matrix, Weighting Ckt &
LPF
Adder
PAL Colour
Encoder
Sub Carrier Generator
Gate
Divider
Sync. Pulses
Video Carrier
AMVSB mod.
Diplexer
FM Mod & Amp.
Audio carrier
Y Signal
V Signal
U Signal
Colour Signal
Sync. Pulse
CCVS
Audio Signal R G B
Antenna
TV Transmitter and Receiver
20 September September 2018

30. SUBJECT: AUDIO VIDEO ENGINNERING SUBJECT CODE: 17537
CHAPTER : 4. TV Transmitter and Receiver
Marks: 20 Marks.
Contents:
Audio and Video signal transmission using AM and FM modulation.
Positive and Negative modulation
Introduction to TV camera tube (Vidicon, Plumbicon, Solid State camera based on CCD.)
Color Picture tube (PIL, Delta gun picture tube, Trinitron)
Block diagram of Colour TV transmitter.
Block Diagram of color TV receiver (PAL D type)
20 September September 2018

31. Block Diagram of color TV receiver
(PAL D type)
TV Transmitter and Receiver
20 September September 2018

32. Monochrome Colour Television R.R.GULATI page no: 551
TV Transmitter and Receiver
20 September September 2018

33. SUBJECT: AUDIO VIDEO ENGINNERING SUBJECT CODE: 17537
CHAPTER : 4. TV Transmitter and Receiver
Marks: 20 Marks.
Contents:
Audio and Video signal transmission using AM and FM modulation.
Positive and Negative modulation
Introduction to TV camera tube (Vidicon, Plumbicon, Solid State camera based on CCD.)
Color Picture tube (PIL, Delta gun picture tube, Trinitron)
Block diagram of Colour TV transmitter.
Block Diagram of color TV receiver (PAL D type)
20 September September 2018