Diploma-Diploma Electronics and Communication 3rd Sem Communication Engineering - I (Gujarat Technological University-2013)
Thursday, 29 August 2013 07:14anudouglas
GUJARAT TECHNOLOGICAL UNIVERSITY
DIPLOMA ENGG.- SEMESTER–III EXAMINATION – WINTEER 2012
Subject code: 331104 Date: 05/01/2013
Subject Name: Communication Engineering - I
Time: 2:30 pm – 5:00 pm Total Marks: 70
Instructions:
1. Attempt all questions.
2. Make suitable assumptions wherever necessary.
3. Figures to the right indicate full marks.
4. English version is Authentic
Q.1 (a) What is Modulation? Define AM, FM and PM with necessary waveforms. 07
(b) Define Antenna in various way. Also mention the functions and properties of it. 07
Q.2
(a) Define modulation Index for AM wave. Explain different methods used to measure it and draw the waveforms for m<1, m=1, m>1 for each method. 07
(b) Compare High Level Modulation with Low Level Modulation. 07
OR
(b) A transistor class C amplifier has a maximum permissible collector dissipation of 20 watts and collector efficiency of 75%. If it is collector modulated with a modulation index of 90%. calculate: (1) maximum carrier power (2) Single Side Band Power
Q.3
(a) Draw and explain the block diagram of Indirect method of FM generation. 07
(b) Explain basic principal of FET reactance modulator. 07
OR
Q.3 (a) Draw and explain the block diagram of stabilized reactance modulator for FM generation. 07
(b) The output voltage of a FM transmitter is given by e=8sin(12000t+8sin1256t) volt. Find (i) modulation index (ii) carrier
frequency (iii) peak frequency deviation (iv) bandwidth
Q.4 (a) What is heterodyne? Draw and explain the block diagram of Super heterodyne AM radio receiver.
(b) Explain phase-shift discriminator circuit used in FM receiver. 07
OR
Q. 4 (a) Explain :(i) Selection criteria of IF frequency 04
(ii) Problems in TRF Receiver. 03
(b) Explain different Mixer circuits used in AM receiver. 07
Q.5
(a) Compare FM receiver with AM receiver. 07
(b) What is fading? Explain different Diversity techniques used to combat the effect of fading. 07
OR
Q.5 (a) Explain the Log-Periodic antenna with neat diagram 07
(b) Explain Ground Wave Propagation with its salient features. 07
| Earning: ₹ 6.05/- |
