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. Even though all circuits are working, the picture tube blanks:    

(A)  if EHT fails.                                  (B)  if AGC fails.

(C)   if Horizontal scan fails.                 (D)  if Vertical scan fails.

b. In order to take scanning beam from bottom of the screen to top, the requirement is:

(A) Horizontal scanning.                       (B)  Equalizing.

(C) Horizontal retrace.                         (D)  Vertical retrace.

             c.   The Video carrier and audio carrier frequencies for channel V of CCIR-B in MHz are:

(A) 175.25 & 180.75                         (B)  175.25 & 179.75

(C)  175.5 & 180.5                             (D)  175.5 & 181.25

             d.   The primary colours in a trichromatic video are:

(A)  Red, Green, Yellow                    (B)  Red, Blue, Yellow

(C)  Green, Red, Blue                         (D)  Green, Blue, Yellow   

             e.   PAL-D delay line is:

(A) Cable                                           (B)  Flip-Flop

(C)  Filter                                            (D)  Acoustic media

             f.    AGC helps in

(A) controlling signal amplitude.          (B)  tuning the carrier frequency.

(C)  control deviation.                          (D)  control synch.

             g.   Composite Video signal in monochrome represents:

(A) Video & sound information           (B) Video & Synch information

(C) Video & Blanking                          (D) Video, sound and Synch

             h.   During TV receiver installation, Balun is generally used between

(A)  Dipole antenna and co-axial cable.     

(B)  Folded dipole antenna and coaxial cable.

(C)  Folded dipole antenna and flat twin cable.      

(D)  Dipole antenna and twisted pair.

             i.    The brightness control is a:

(A) a.c. control.                                  (B) AGC control.

(C) AFC control.                                 (D) d.c. control.

             j.    Gamma correction helps in:

(A)  linearising.                                    (B)  creating sharp picture.

(C)  differential phase error.                 (D) improving colour.

Answer any FIVE Questions out of EIGHT Questions.

Each question carries 16 marks.

Q.2     a.   What are the components of a composite video signal.  Draw a waveform for the last line of a field of interlaced scanning giving the details of normalized amplitude and timing of each of the component if the image has 7 scale grey scale.                                                                           (10)

             b.   Why the number of scanning lines are always odd numbered in interlaced scanning?  Give examples.                                                                      (6)

Q.3     a.   How do you decide the bandwidth of a video signal and explain what are the factors on which it depends?                                                             (8)

             b.   When AM SSB can save 50% of the r.f. video spectrum, why AM VSB is preferred?  What is the effect when FM is used instead of AM for video information?                                                      (8)

Q.4     a.   In a PAL system U and V are transmitted on a single resultant sub-carrier, how is this achieved?  Also explain the need of phase alternation during every alternate line.                                         (10)

b.   Explain briefly how chrominance is transmitted with in the monochrome spectrum?              (6)

Q.5     a.   Bring out the major differences between PAL and SECAM TV system.              (8)

     b.   Draw the block diagram of a PAL encoder and explain its working.                    (8)

  Q.6     a. What is a pickup tube?  What are the different methods used in such tubes?  Explain the construction and working of Vidicon Camera.                (10)

             b.   What is the need of second anode in a picture tube?  Give examples.                  (6)

Q.7     a.   Draw an electronic tuner and explain how tuning is achieved?                              (8)

b.   If an micro controller based tuner is used how does search operation is executed.  Explain the principle.                                                                 (8)

Q.8     a.   Draw the block diagram of a colour TV receiver and explain the importance of each stage.  Also draw the spectrum or waveforms at each output.                                                                              (10)

             b.   What is de-gaussing?  How does it work?                                                          (6)

Q.9           Write short notes on:

(i) Pincushion distortion.

(ii) Automatic brightness control.

(iii) TV test charts.

(iv) Booster amplifier.                                                                               (4 x 4)