User:Sgokhale/Temp/PHE 16 TMA-2 (2006).doc

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1.State with reasons whether following statements are True or False.

i) Tuned frequency receivers (TFR) are most commonly used in audio communication.

ii) Image frequency can be reject by tuned IF amplifier.

iii) Failure of horizontal scanning circuit results into appearance of horizontal line on the TV.

iv) Tunnelling phenomenon is observed only in direct bandgap semiconductor junctions.

v) Modal dispersion is prominent in graded index multimode fibre.

vi)Any programme on computer is executed in machine level language.

vii)Router in a computer network protects unauthorized entry into a LAN.

viii)Ethernet supports ring topology.

ix) TCP/IP has a seven layered structure.

x)Peer to peer networking essentially facilitates wireless connectivity.

2.(a)State the advantages of using superheterodyne principle in receivers. (3)

(b)A transmitter class C final stage amplifier is supplied with 15 V dc supply. Calculate what equivalent RL the transistor must see, in order to produce an RF output of 10 W. If the transmitter is to be connected to an antenna with 50  load impedance, design and draw an L network to provide required match. (5)

(c)What is the importance of AGC circuit in a receiver?(2)

3.(a)A transmitter is sending a PAL signal with 4:3 aspect ratio. You have a TV set with a square display screen. With proper diagram, explain how the images will appear on your set.(4)

(b)What are the advantages of using dichroic mirrors instead of filters in a colour camera tube?(2)

(c)What are the advantages of using a flat screen displays in a TV set?(2)

(d)Which synchronisation signals are transmitted along with colour TV video signal? (2)

4.(a)Calculate the diameter of a parabolic reflector required to provide a gain of 60 dB at 10 GHz frequency. The aperture efficiency is 0.6. Calculate the effective area of the antenna and its 3 dB beam width. (4)

(b)Explain the process of bunching in reflect klystron. (3)

(c)What are uses of following waveguide components?

(i) Isolator; (ii) Magic T ; (iii) Resonant Cavity.(3)

5.(a)An optical fibre has a numerical aperture of 0.20 and cladding refractive index of 1.59. Determine (i) the acceptance angle for the fibre in water, which has refractive index of 1.33; and (ii) the critical angle at core-cladding interface.(4)

(b)Discuss various reasons for attenuation of signal in an optical fibre. (3)

(c)Compare the performance of LED and laser diode as optical sources in a fibre optic communication system.(3)

6.(a)Write down the steps involved in moving a data in memory location A to location B, location B to location C and location C to location A.(3)

(b)Describe in brief various types of networking software.(5)

(c)Write down any four peripheral devices of a computer.(2)

7.(a)What are the typical characteristics of a modem?(3)

(b)Explain the use of fire wall in computer network system.(3)

(c)Compare the merits and demerits of ring topology and star topology.(2)

(d)Justify the need of LAN protocols.(2)

8.(a)Describe various layers of OSI model.(4)

(b)How connection between DTEs is established in X.25 scheme?(2)

(c)Write down the method of operation of search engines. (2)

(d)Describe the domain name structure of Internet addresses.(2)

9.(a)Explain how P2P improves reliability of computer network functioning.(3)

(b)How does a mobile device connect to the Internet using WAP?(3)

(c)What are the different ways of connecting devices together without wires?(2)

(d)Write two applications of Bluetooth technology. (2)

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