DipIETE – ET (NEW SCHEME) – Code: DE62
Subject: TELECOMMUNICATION SWITCHING SYSTEMS
Time: 3 Hours
Max. Marks: 100
NOTE: There are 9 Questions in all.
· Question 1 is compulsory and
carries 20 marks. Answer to Q.1 must be written in the space provided for it in
the answer book supplied and nowhere else.
· Out of the remaining EIGHT
Questions, answer any FIVE Questions. Each question carries 16 marks.
· Any required data not
explicitly given, may be suitably assumed and stated.
Q.1 Choose the correct or the best alternative in the following: (2
10)
a. Telephone
network follows _________ switching.
(A) Message (B) Circuit
(C) Packet (D) Channel
b. Automatic Telephony was invented by ___________.
(A) Marconi (B) Abraham Lincoln
(C) A.B.
Strowger (D) Charles Babbage.
c. Telephone
Traffic intensity is measured by _________.
(A) Coloumbs (B) Faraday
(C) Erlang (D) Watts
d. Switching
system with 
sets of contacts with activators is known as
_________.
(A) Crossbar (B) Step by Step
(C) Electronic (D) Mechanical
e. Final
selector stage of Step-by-Step system determines ___________ digits of
telephone number
(A) Last
one (B) Last two
(C) Last
three (D) None
f. The
grade of service is the ratio of __________.
(A) 
(B) 
(C) 
(D) 
g. The number of outgoing trunks to which an incoming trunk can obtain
connection is called _______
(A) Connectivity (B) Congestion
(C) Traffic (D) Availability
h. Number
of minimum cross points required for a 3 stage network with M incoming trunks
and N outgoing trunks is _____________.
(A)
(B) 
(C) 
(D) 
i. During
signal exchange time, Proceed to send signal originates from _________.
(A) Calling terminal (B)
Exchange Switching System
(C) Called
terminal (D) Calling and called terminal
j. Minimum
number of Central processor required in SPC Switching System is _____________.
(A) 1 (B) 2
(C) 3 (D) 4
Answer any FIVE
Questions out of EIGHT Questions.
Each question
carries 16 marks.
Q.2 a. Explain
the basic functions of a Switching System. (8)
b. In a 1000 line
strowger exchange using 1000 uniselector.
Show the trunking diagram when subscriber 254 establishes connection to
subscriber 821. (8)
Q.3 a. Define
the following :
(i) Busy hour (ii) Grade of Service
(iii) Full availability (iv) Traffic Erlang (8)
b. During busy hour 1500 calls were offered to a group
of trunks and 5 calls were lost. The
average call duration is 3 minutes. Find
(i)
Traffic offered (ii) Traffic carried
(iii)
Traffic lost (iv) Grade of Service
(v) Total duration of period of congestion. (8)
Q.4 a. Explain with the help
of diagram
(i) Skipped
grading (ii) Homogeneous grading (8)
b. Design
a 3 stage network for connection of 100 incoming and 400 outgoing trunks. (8)
Q.5 a. With
neat sketch explain the functioning of space switch. (8)
b. Explain
the working of T-S-T switching network. (8)
Q.6 a. What
are the sequences of operations of call processing function? Explain briefly. (10)
b. Explain
load sharing and synchronous operation configuration of SPC system. (6)
Q.7 a. What is multiframing? Explain 30-channel PCM system briefly. (8)
b. With
block diagram explain briefly CCITT signalling system number 7. (8)
Q.8 a. Write a note on ALOHA protocol. (8)
b. Compare
BUS and RING LAN topologies. (8)
Q.9 a. Explain briefly ISDN. (8)
b. With
neat sketch explain the principle of cellular mobile networks. (8)