Cables Trenzados

Set No. 1

Code No: R05320401

III B.Tech II Semester Regular Examinations, Apr/May 2008
TELECOMMUNICATION SWITCHING SYSTEMS AND NETWORKS
( Common to Electronics & Communication Engineering and Electronics &
Telematics)
Time: 3 hours
Max Marks: 80
Answer any FIVE Questions
All Questions carry equal marks
⋆⋆⋆⋆⋆
1. (a) Why is it necessary to keep the magnetic diaphragm in an earphonedisplaced
from its unstressed position? How is this achieved?
(b) What happens if the ratio φ/φ0 is not very small in case of an earphone?
(c) Estimate the bandwidth requirements of a single satellite that is to support
20 million telephone conversations simultaneously.
[8+4+4]
2. (a) Explain the operation of input controlled and output controlled time division
space switch with the helpneat sketches?
(b) A PABX is designed using an output-controlled digital time division space
switch for supporting 128 subscribers. The transmission between the subscribers and the exchange is analog. On an average, 25 % of the subscribers
are active simultaneously, compare the cost of output- controlled and memorycontrolled configurations.
[8+8]
3. (a) A subscriber loop of 18km is to besupported from an exchange that uses
a 40 V battery with a 400 Ω short-circuit protection resistance. Electronic
telephones are used as the subscriber instruments. Determine the wire gauge
that needs to be used.
(b) Explain in detail about telecommunication network topologies?

[8+8]

4. (a) Define grade of service? Give expression for grade of service and explain why
it is called as callcongestion.
(b) The traffic statistics of a company using a PABX indicates that 180 out-going
calls are initiated every hour during working hours. Equal number of calls
comes in. Each call lasts for 200 seconds on the average . If the GOS required
is 0.05, determine the number of lines required between the PABX and the
main exchange.
[8+8]
5. (a) Describe data communication circuit configurations.(b) What are the components of Data Communication network ? Explain. [8+8]
6. (a) Define open system interconnection. Name and explain functions of each of
the Layers of the OSI model.
(b) Describe the operation of star, bus ring and hybrid Network topologies [8+8]
7. (a) What are the data link protocols used by ISDN ? Explain.
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Set No. 1

Code No: R05320401

(b) Describe the fourcategories of messages in the ISDN network layer

[8+8]

8. (a) Explain the format of STS 1 frame in details.
(b) What are the functions of STS- Multiplexes and add / drop multiplexers.
(c) Explain device layer relationship in SONET
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[6+6+4]

Set No. 2

Code No: R05320401

III B.Tech II Semester Regular Examinations, Apr/May 2008
TELECOMMUNICATION SWITCHING SYSTEMSAND NETWORKS
( Common to Electronics & Communication Engineering and Electronics &
Telematics)
Time: 3 hours
Max Marks: 80
Answer any FIVE Questions
All Questions carry equal marks
⋆⋆⋆⋆⋆
1. (a) Compare the features of single stage and multistage switching network configurations?
(b) A fully connected network supports full duplex communication using unidirectional links. Show that thetotal number of links in such a network with n
nodes, is given by 2×n C2 .
[8+8]
2. (a) Define each of the following terms: program, procedure, processor, process,
user, task, job and subroutine.
(b) Find the blocking probability of a three stage network for M=N=2048,p=q=16
and α = 0.1 for S= 16, 24 and 32.
[8+8]
3. (a) What are the major components of telecommunication network? Explain indetail about subscriber loop systems.
(b) An exchange uses a -40 V battery to derive subscriber lines. A resistance
of 250Ω is placed in series with the battery to protect it from short circuits.
The subscribers are required to use a standard telephone set which offers a
d.c. resistance of 50Ω. The microphone requires 23mA for proper functioning.
Determine the farthest distance from the...