Code: DE-18                                                                 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. Horizontal resolution is directly proportional to    

(A)  Horizontal lines                             (B)  Contrast

(C)   Video Bandwidth                         (D)  Brightness

b. The approximate voltage required in Trinitron at second anode is

(A) 1 KV.                                           (B)  10 KV.

(C) 30 KV.                                         (D)  60 KV.

             c.   The sideband power in a VSB up to 1.25 MHz is proportional to

(A) .                                              (B) .

(C) .                                            (D)  .

             d.   In a PAL system the Hue is represented by  

(A)  Amplitude of chrominance.          (B)  Phase of chrominance.

(C)  Amplitude & Phase.                     (D)  Differential chrominance.        

             e.   An LPT T.V. station transmits about

(A) 1 KW.                                         (B)  1 W. 

(C)  1 MegaW.                                   (D)  100 KW.

             f.    An electronic tuner selects a

(A) fixed channel.                               (B)  any program.

(C)  whole spectrum.                           (D)  only one station.

             g.   AGC helps in

(A) Controlling signal amplitude.          (B) Tuning the channel.

(C) Synchronization.                            (D) Controls deviation.

             h.   VSB correction in colour IF amplifier is achieved by a dip at 33.4 MHz by

(A)  10 dB.                                         (B)  20 dB.

(C)  30 dB.                                         (D)  40 dB.

             i.    DC component in a Video signal represents presence of:

(A) Brightness.                                    (B) Contrast.

(C) Saturation.                                     (D) Hue.

             j.    The frequency of 33.4 MHz in the IF spectrum is:

(A)  Video IF.                                     (B)  Audio IF.

(C)  sound carrier.                               (D) both, the Video and Audio IF.

Answer any FIVE Questions out of EIGHT Questions.

Each question carries 16 marks.

Q.2     a.   Define Vertical and horizontal resolution, show how they are related and also explain dependence of Video bandwidth.                                          (8)

             b.   Calculate the Bandwidth of Video signal in a 625 line system that is operated by a 50 Hz line frequency.                                                                (8)

Q.3     a.   What does the following terms indicate:                                                        (4 x 2)

(i) Equalizing pulses.

(ii) Serrated pulses.

                  Explain by using neat diagrams.            

             b.   Discuss the merits and demerits of positive and negative amplitude modulation and justify the choice of negative modulation in TV.                   (8)

Q.4     a.   Draw a typical Plumbicon pickup tube and explain its working.  What are its salient features?                                                                     (10)

b.   How the following is achieved in TV cameras:

(i) Zooming.

(ii) Primary color separation.                                                                (2  3)

Q.5     a.   What is the need of color difference signals in color video transmission, explain how compatibility is obtained.                                                           (8)

     b.   How sub-carrier is chosen for chrominance transmission?                                   (8)

  Q.6     a. Briefly explain with the help of diagram EHT build up in a TV receiver.                (8)

             b.   Give logical reasons for

                   (i) No sound only picture

                   (ii) Low Brightness                                                                                             (8)

Q.7     a.   Design a Yagi antenna consisting of five elements for receiving channel V, T.V. signals.                   (8)

b.   Draw the schematic of an electronic tuner and explain how these are used to select programs in VHF and UHF.                                                  (8)

Q.8     a.   How sound and video signal are separated and detected in inter-carrier T.V. receivers?                  (8)

             b.   Explain encoding and decoding of chrominance signal, in a TV system.                (8)

Q.9     a.   What is color burst, what is its function?                                                             (4)

b.   In a color receiver why color killer is required, draw a simple circuit and explain its working.                                                                      (6)

c.   Draw the circuit of a sync separator with noise canceller and explain its working.                (6)