PHE-16 Communication Physics Solved Assignment 2020

Tutor Marked Assignment
COMMUNICATION PHYSICS
Course Code : PHE-16
Assignment Code: PHE-16/TMA/2020
Max. Marks: 100

1. State with reasons whether the following statements are True or False. (210)
i) Optical fibre is an ideal medium for microwave transmission.
ii) Adding redundant bit in a transmitted signal ensures error free communication.
iii) A transmission line with infinite VSWR is ideal for signal transmission.
iv) Bandwidth of frequency modulated (FM) signal is narrower than that of amplitude
modulated (AM) signal.
v) Amplitude shift keying is modulation of digital carrier by analog signal.
vi) GSM is a spread spectrum technology.
vii) TRF receivers are preferred over super-heterodyne receivers in audio
communication.
viii) Schottky diode can handle higher frequency signals than p-n junction diode.
ix) Assembly language programmes are portable.
x) Same web browser can be used to access Internet as well as Intranet network.
2. a) In case of a receiver explain the following terms with the help of graphs:
(i) sensitivity, (ii) half power point, (iii) linearity and (iv) fidelity. What should be
their ideal behaviour/value? (8)
b) Why do we prefer repeating waveforms for characterizing any communication
system? (2)
3. a) Draw the circuit representing a practical transmission line in terms of lumped
components. What are the values of R and G in case of ideal transmission line?
Why? (2+1+2)
b) A computer key board has 108 keys. Assuming equal probability of any key pressing
calculate the information content, I, carried by each key. Prove that this information
is more than the information carried by a key on the number pad of a touch tone
telephone. [Hint: Touch phone has 16 keys on its pad] (3+2)
4. a) 20 kHz audio signal is amplitude modulated over a 100 kHz carrier frequency. The
peak amplitude of carrier wave is 10 V. If the modulation index is 0.8, find out the
frequencies present in the modulated output. Also calculate the ratio of maximum
and the minimum amplitude of the envelope of modulated signal. (5)
b) Depict the digital signal 1001101110 in (i) unipolar RZ, (ii) bipolar NRZ, and
(iii) Manchester code. (1+1+3)
4
5. a) Explain the time division switching used in telephony. (5)
b) Design a TDM system to handle 3 PAM channels if the maximum input frequency of
each channel is 5 kHz. (5)
6. a) Explain the special features of stereo receiver circuit as compared to normal FM
receiver. (5)
b) Explain the functions of blanking and synchronizing pulses in a television receiver.
How are these functions accomplished by using a sync separator circuit? (2+3)
7. a) Discuss the various types of microwave horn antennae on the basis of their
construction, directivity and applications. (5)
b) Compare the different types of optical fibres on the basis of their construction.
Explain, how the modal dispersion is avoided in case of graded index fibre. (3+2)
8. a) Explain the process of instruction execution in a van Neumann machine. (5)
b) Describe the two main LAN protocols. How is data collision avoided in case of
token ring protocol? (3+2)
9. a) Compare the merits and demerits of various types of datagram switching methods. (5)
b) What is blue tooth technology? How are the concerns regarding the interference
among blue tooth device connections resolved?

PHE-16, PHE 16, PHE16, PHE-016, PHE016, PHE 016