Code: DE18                                                                   Subject: TELEVISION ENGINEERING

Time: 3 Hours                                                                                                     Max. Marks: 100

NOTE: There are 9 Questions in all.

· Question 1 is compulsory and carries 20 marks. Answer to Q. 1. must be written in the space provided for it in the answer book supplied and nowhere else.

· Out of the remaining EIGHT Questions answer any FIVE Questions. Each question carries 16 marks.

· Any required data not explicitly given, may be suitably assumed and stated.

Q.1       Choose the correct or best alternative in the following:                                         (2x10)

a. The Aspect Ratio in a Conventional TV system is

(A)  1:2                                               (B)  2:1

(C)   3:4                                              (D)  4:3

b. Video transmission in CCIR – B standard is:

(A) Narrow band FM                         

                   (B) Amplitude Modulated Double side Band

(C) Amplitude Modulated Vestigial side Band                                                                  

(D) Quadrature amplitude Modulated

             c.   The colour sub-carrier frequency in one of the CTV systems is:

(A) 5.5 MHz                                      (B)  38.9 MHz

(C)  33.4 MHz                                    (D)  4.43 MHz

             d.   Diplexer is used at the

(A)  T.V. Transmitter                          (B)  T.V. Receiver

(C)  Only color T.V. Receiver             (D)  In DTH system          

             e.   Luminance signal is generated by adding following signals

(A) 0.3 R + 0.22 B + 0.59 Y            

(B)  0.3 R + 0.59 G + 0.11 B

(C)  0.8 (R – Y) + 0.2 (G – Y)           

(D)  0.3 (R – Y) + 0.59 (G – Y) + 0.11 (B – Y)

             f.    AFT circuit in a TV receiver is located in

(A) RF tuner                                      (B)  Vertical oscillator

(C)  IF amplifier                                   (D)  Video amplifier

             g.   The pattern of scanning Lines in a video system is called

(A) Re-trace                                       (B) Resolution

(C) Raster                                          (D) Interlace

             h.   If the picture is rolling the fault may be due to

(A)  Absence of vertical sync               (B) horizontal sync failure

(C)  fault in AGC                                 (D)  fault in IF section

             i.    The EHT voltage supply for the anode of a picture tube is generated in

(A) Mains transformer                         (B) Vertical output stage

(C) Horizontal output stage                  (D) Horizontal deflection oscillator

             j.    Balun is used to

(A) Terminate a coaxial cable            

(B)  Join two coaxial cables

(C)  Connect indoor arial                    

(D) Connect Folded dipole to co-axial cable

Answer any FIVE Questions out of EIGHT Questions.

Each question carries 16 marks.

Q.2     a.   Define and explain the effect of following on the reproduction of picture

                   (i) Vertical Resolution                          (ii) Progressive scanning

                   (iii) Horizontal Resolution                                                                                   (9)

             b.   Why synchronization is needed in Video system but not in audio systems.            (7)

Q.3     a.   Explain the principle and working of Vidicon picture tube.                                   (8)

             b.   How a colour camera is different from monochrome camera. Explain.                 (4)

             c.    What is degaussing and why is required?                                                            (4)

Q.4     a.   What are the advantages of using VSB instead of SSB to transmit Video. Draw the VSB spectrum for channel V of CCIR-B standard, also indicate the sound carrier location with respect to picture carrier location.                                              (10)

b.   What is the need of a Diplexer in a intercarrier system, what is the principle behind its working?                                                                 (6)

Q.5     a.   Define the terms:  pedestial height, blanking pulses.                                             (8)

     b.   How is weighting correction achieved before quadrature modulation?                  (8)

  Q.6     a. Explain how encoding and colour difference signals is activated in a quadrature modulator with the help of a block diagram?                                    (8)

             b.   What are the functions of  AFT and AGC. Explain the principle of working of keyed AGC.                                                                       (8)

Q.7     a.   Explain with a diagram the working of PIL colour picture tube.                            (8)

b.   Explain

                   (i)  Convergence                                 

                   (ii)  function of purity magnets                                                                            (8)

Q.8     a.   What is the need of the following in a color TV receiver:

(i) Color Killer

                   (ii) Delay line                                                                                                      (8)

             b.   Bring out the differences between NTSC, PAL and SECAM systems.                (8)

Q.9           Write short notes on:

(i) Booster Amplifier

(ii) Remote Control

(iii) TV Test charts.

(iv) TV Receiving antenna                                                                         (4 x 4)