Bhavnagar University 2007 B.Sc Computer Science COMPUTER COMMUNICATIONS - Question Paper

COMPUTER COMMUNICATIONS



Time: three hrs
Max Marks: 70

First ques. is Compulsory

ans any 4 from the remaining ques.

All ques. carry equal marks

ans all parts of any ques. at 1 place

1. a) Write the major components of a Data Communication System.
b) calculate the maximum bit rate for a voice channel with Signal-to-noise ratio of 20dB.
c) For a CAT five UTP cable, write its Bandwidth, Data Rate, and Distance
d) What do you understand by Companding?
e) Show the null modem connection details used ranging from 2 DTEs.
f) Distinguish ranging from dumb terminal and intelligent terminal.
g) What do you understand by Pulse Stuffing?

2. a) Distinguish ranging from Data Processing and Data Communications. elaborate the different communication tasks that are being performed in a data communication system.

b) describe the subsequent terms with suitable examples: Data, Information, Analog data, Digital data, Signal, Signalling and data transmission.

3. a) Compare the different kinds of transmission facilities for data communications for an intended application of your option. On the basis of your findings, draw whatever conclusions you can for selecting the most economically attractive option.

b) Write clearly the capabilities, limitations and applicability problems of NRZ and RZ codes.

4. a) Write the requirements of a good signal design for data encoding? Identify the more practically used encoding schemes for different LAN topologies and Wide Area Networks.

b) Distinguish ranging from EIA-232-E and ISDN physical interfaces in respect of 4 important characteristics.

5. a) A data source produces 8-bit ASCII characters. Derive an expression for the maximum data rate (rate of ASCII data bits) over a B-bps line for the following:
i) Asynchronous transmission with a 1.5 unit stop bit
ii) Synchronous transmission with a frame consisting of 48 control bits and 128 info bits. The info field contains 8-bit ASCII characters.

b) elaborate the fault control codes for synchronous serial data communications? obtain such codes for the subsequent messages:
i) DATA COMM (ASCII hex : 44 41 54 41 20 43 4F 4D)
ii) 100010010000011010100

6. a) define the role of a terminal in data communication system. Briefly discuss various kinds of terminals used for various applications.

b) Compare the subsequent communication processing devices:
MULTIPLEXER. CONCENTRATOR and FRONT-END PROCESSOR

7. a) Use sketches and additional text to define the subsequent with respect to BAUD RATE, BIT RATE, and BANDWIDTH i) FSK modem ii) 4.phase PSK modem

b) discuss in terms of Data Link Control and physical layer concepts how fault and flow control are accomplished in Synchronous Time division multiplexing.

8. Write short notes on the following:
a) Protocol Architecture b) Effect of bandwidth on a digital signal
c) HDLC d) Statistical Division Multiplexing

Earning:   Approval pending.