Maharashtra State Board of Technical Education 2008 Diploma Electronics and Communication Analog Communication - Question Paper
Sample Question Paper-I
ELECTRONICS ENGINEERING GROUP Q A7 O
ET/EX/EJ/EN ' 3
COURSE COURSE CODE SEMESTER SUB TITLE MAX MARKS
FOURTH
ANALOG COMMUNICATION
80 TIME: 3 HOUR
Instruction:
1. All questions are compulsory.
2. Illustrate your answers with neat sketches wherever necessary.
3. Figures to the right indicate full marks.
4. Assume suitable data if necessary.
5. Preferably, write the answers in sequential order.
Q.1.A) Attempt Any Four of following 08 Marks
a) Define Half Duplex and Full Duplex with the help of sketch.
b) State the principle of operation of superheterodyne receiver.
c) State following terms related to antenna.
i) Polarization ii) Directivity
d)State the frequency ranges for following
i) Audio Frequency ii) Voice Frequency
iii) Microwave Frequency Band iv)VHF frequency band
e) Draw block diagram of communication system.
f) State the need for modulation.
Q.1.B) Attempt Any 2 of following 08 Marks
a) A load of 400Q is used to match 600Q transmission line to achieve SWR=1 . Find out the required characteristic impedance of quarter wave transformer connected directly to the load.
b) Explain the concept of actual height and virtual height with the help of figure.
c) Draw AM wave for following conditions
1) i) fc=300 KHz , 3 Vp_p
ii) fm=1 KHz , 1 Vp_p
2) i) fc=300 KHz , 3 Vp_p
ii) fm=2 KHz , 1 Vp_p
Q.2. Attempt Any 3 of following 12 Marks
a) State sequential steps to perform the experiment of calculating modulating index
using Trapezoidal pattern.
b) Explain the working of PLL based FM detector with the help of block diagram.
c) Compare loop Antennas and Ferrite rod antenna w.r.t. following points.
i)Working Principle ii)Construction
iii)Radiation pattern iv)Application
d) Give the different reasons for Fading.
Q.3. Attempt Any 3 of the following 12 Marks
a) Derive the relationship between transmitted AM power and carrier power. What will happen to total transmitted power if modulation index is unity?
b) Justify why output voltage of balanced slope detector decreases above and below the resonance frequencies (fc + Af , fc - Af) ?
c) Draw and explain equivalent circuit of transmission line.
d) Draw labeled sketch of Yagi-uda antenna .
i. state function of each element in antenna.
ii.Give applications of Yagi antenna.
iii.Draw radiation pattern.
Q.4. Attempt any four of the following 16 Marks
a). With respect to sky wave propagation define the following terms.
i) Virtual height ii) Maximum usable frequency
iii) Skip Distance iv) Critical Frequency
b). Draw radiation pattern for following resonant dipoles for following lengths.
i) L = l ii) L=3l iii) L=3l/2 iv) L=l/2 where L=length of dipole.
c). What is the need of AGC? Explain simple AGC used in radio receiver.
d). In what way ground way propagation differs from sky wave propagation.
|
First group of multipliers |
|
f. Explain the characteristics determining the performance of AM Radio receiver.
|
j Carrier Combining n/w |
 |
Crystal
Oscillator
Q.5. Solve any three of the following 12 Marks
a) What is a stub? Give advantages of stub matching.
b) Explain the Duct propagation with sketch and give its applications.
c) How amplitude is limited in a ratio detector circuit ?
d) Explain FM signal generation using reactance modulator method.
Q.6. Solve any three of the following 12 Marks
a) Distinguish between Phase discriminator and Balanced slope detector on the basis of i.)Output characteristic ii.) Linearity iii). Amplitude iv)limiting Application
b) Explain standing wave pattern for a transmission line.
c) Represent AM signal in frequency domain and time domain.
d) What is major lobe, miner lobe and side lobe in radiation pattern.of antenna.
|
Attachment: |
| Earning: Approval pending. |
