Rashtrasant Tukadoji Maharaj Nagpur University 2009 B.E Electronics & Communication Engineering Winter , Faculty of Engineering and Technology, LINE COMMUNICATION AND SWITCHING SYSTEM - Question P

part A

1. (a) discuss the advantages and disadvantages of subsequent codes:
(i) Morse code
(ii) Cable code
(iii) 7.5 unit teleprinter code.
(b) If the duration of the smallest element in a telegraphic code is 20msec, compute the speed in Baud, character per seconds, and words per minute in:
(i) Morse code
(ii) Cable code
(iii) five unit synchronous code and
(iv) 7.5 unit teleprinter code.

2. (a) Compare and discuss the 2 methods of working of differential duplex circuit. Why are they so called?
(b) elaborate telephone relays? discuss every component of relays used in telephone.
(c) Differentiate ranging from telegraphy and telephony.

3. (a) define with the aid of simple sketch arrangement made in a teleprinter transmitter to ensure a high degree of accuracy in the duration of the individual elements comprising the teleprinter signals.
(b) What is the purpose of the start-stop clutch used in the receiving mechanism of a teleprinter? define the construction and action of such a clutch with the aid of a suitable sketch.

4. Write short notes on:
(i) Fascimile
(ii) Telegraph Repeater
(iii) Baudot Multiplex
(iv) Telephone Receiver

5. (a) What is sidetone? How does it affect a telephonic communication? discuss the principle of antiside tone circuit.
(b) Draw the circuit of subscriber telephone set used in CB manual exchange. discuss functions of all components.

part B

6. (a) Draw and discuss the trunking diagram of a 1000 line exchange. elaborate the reasons for every subscriber being given with 1 uniselector?
(b) How can the flow of telephone traffic through an exchange be conveniently defined? describe in this connection the subsequent terms:
(i) Busy hour
(ii) Unit Call
(iii) Calling rate
(iv) avg. holding time

7. (a) For how many minutes during the busy hour is a single selector engaged if it carries an avg. traffic 0.75 erlang?
(b) discuss the subsequent terms used with the selectors of an auto exchange:
(i) Traffic unit
(ii) Grade of service
(iii) BHCA
(iv) Traffic intensity.
(b) discuss BORSCHT and its function.

9. (a) discuss the concept of ISDN. How the various systems are transmitted over the identical channel? discuss with proper sketch.
(b) discuss the principle of operation of power line carrier communication system.

10. Write short notes on any THREE:
(i) Cross bar exchange
(ii) SLIC
(iii) Long haul carrier telephone system
(iv) CCITT No. seven signalling.

Earning:   Approval pending.