Gujarat University
MCA Semester IV
Networking Technologies I
Date: 26th July, 2000 Marks:50
Instructions:
1. Attempt all questions of each section in separate answer-books.
2. Assume suitable data wherever necessary.
3. Figures to the right indicate full marks.
Section I
Q-1 Answer the following: [9]
a. Why is modulation needed? What is the relation of the modulating signal, the carrier and the channel?
b. Give advantages of Digital modulation.
c. Explain briefly the concept of TDM.
d. What is guard band? Why are they needed? How much percentage of bandwidth is wasted in case of FM?
e. A TDM system is designed for digital signals. The system can send 100,000 samples/second. How many users can it handle if each user is sampled at 15 kHz?
f. List the key medium characteristics that affect the performance.
Q-2 (a) Explain the following with proper illustration: Absorption, Retection, and Noise [3]
(b) Explain the AM with the help of waveforms. Give the example of systems which uses AM. [3]
(c) How many 6 MHz TV signals can fir into MF band? The SHF band? [2]
OR
Q-2 (a) What is synchronous modulation? Why is it used in place of asynchronous modulation in many cases?
[3]
(b) Explain the FDM with its advantages & disadvantages. [3]
(c) Give two examples of application in which full-duplex communication is needed. Why is FDM often
choosen? [2]
Q-3 Write short notes on any three: [8]
a. Electromagnetic Spectrum
b. Sampling
c. Analog to Digital conversion
d. Fiber optics
e. Noise
Section II
Q-4 (a) Differentiate between: [6]
1. Framing error & overrun error
2. Format & Protocol
3. RS-232-C & RS_423-C
4. Pulse & tone dialing
(b) List and explain the signals exchanges between DTE and DCE. [3]
Q-5 (a) What does network topology mean? What are the implications of having different topologies? What are the
critical reliability issues for each topology. [5]
(b) Explain the general functions of modem. [3]
OR
Q-5 (a) Discuss SDLC giving its key characteristics. [5]
(b) Compare the Twisted pair, Coaxial cable and fiber optics cable. [3]
Q-6 Write short notes on any three: [8]
a. NULL modem
b. OSI model
c. Packet switching
d. Token passing
e. Private exchanges
