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Posted By: jothi vignesh Member Level: Gold Posted Date: 07 Jul 2008
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2005 Anna University B.E TELECOMMUNICATION SYSTEM & SERVICES Question paper
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Code: A-17 Subject: TELECOMMUNICATION SYSTEM & SERVICES
Time: 3 Hours Max. Marks: 100
NOTE: There are 11 Questions in all.
Question 1 is compulsory and carries 16 marks. Answer to Q. 1. must be written in the space provided for it in the answer book supplied and nowhere else.
Answer any THREE Questions each from Part I and Part II. Each of these questions carries 14 marks.
Any required data not explicitly given, may be suitably assumed and stated
Q.1 Choose the correct or best alternative in the following: (2x8)
a. Equipment that controls the electrical termination of ISDN at the user's premises is called
(A) NT1. (B) NT2.
(C) NT3. (D) NT4.
b. A device that links two homogeneous packet broadcast local network is
(A) HUB. (B) Repeater.
(C) Gateway. (D) Bridge.
c. In a telephone network call waiting feature requires two switching paths to be set up simultaneously and both the paths must use
(A) different signalling scheme.
(B) same signalling scheme.
(C) two orthogonal signalling scheme.
(D) two signalling scheme with appropriate phase delay.
d. Which one of these can have the highest data transfer speed :
(A) ISDN. (B) DSL.
(C) Cable Modem. (D) VSATs.
e. DQDB is an acronym for ________________.
(A) Distributed Queue Database.
(B) Differential Queue Database.
(C) Data Queue Dual Bus.
(D) Distributed Queue Dual Bus.
f. In ___________, each packet of a message need not follow the same path from sender to receiver.
(A) Circuit Switching.
(B) Message Switching.
(C) Virtual Approach to Packet Switching.
(D) Datagram Approach to Packet Switching.
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Index Next>>g. The signal to noise ratio for a voice grade line is 30.1 dB or a power ratio is 1023 :1. The maximum achievable data rate on this line whose spectrum ranges from 300 Hz to 4300 Hz is
(A) 6200 bps. (B) 9600 bps.
(C) 34000 bps. (D) 31000 bps.
h. Which transmission mode is used for data communication along telephone lines?
(A) Parallel (B) Serial
(C) Synchronous (D) Asynchronous
PART I
Answer any THREE Questions. Each question carries 14 marks.
Q.2 a. Explain common channel signalling scheme (CCS) and CCS message format for three unit message. (7)
b. Briefly explain the following :
(i) Cross talk.
(ii) D-conditioning.
(iii) Jitter.
(iv) Impulse phase hit. (7)
Q.3 a. What is the purpose of an Echo-suppressor? Why is it necessary for successful data communication? Which forms of data communication - simplex, half duplex or full duplex is not useful with an enabled echo suppressor? (6)
b. Briefly explain the following : (8)
(i) Concentrator.
(ii) Subscriber's loop.
Q.4 Explain in detail the following :
(i) Video & Voice response systems.
(ii) Wired Home and Paperless office. (7)
(7)
Q.5 a. Explain with proper block diagram the principle of operation of modern telephone system. Explain frequency characteristics of DTMF. (8)
b. In a packet switched network circuit determine the packet size which minimizes the total delay. (6)
Q.6 a. Derive an expression for the blocking probability of a TSTS switch if each stage is individually non blocking. (5)
b. What is ALOHA? Derive the expression for the throughput of a slotted ALOHA. (9)
2
<>PART II
Answer any THREE Questions. Each question carries 14 marks.
Q.7 a. What is the purpose of a scrambler and descrambler circuit? Explain the operations of these circuits. (8)
b. What types of digital circuit is used as a bit splitter? What are the advantages and disadvantages of a 16 QAM modulator vis-à-vis a 16 PSK modulator? (6)
Q.8 a. With a neat block diagram explain Ethernet Interface Adapter. (6)
b. How does CSMA/CA differs from CSMA/CD? Explain the fast Gigabit Ethernet. What is the chief use of Gigabit Ethernet? (8)
Q.9 In a local area network there are workstations and personal computers.
(i) Show the distribution of MTA and UA in this environment.
(ii) How would the message exchange take place between two personal
computer and a workstation? (7)
(7)
Q.10 a. Describe with diagram the design of Cellular Radio telephone system. (9)
b. Discuss advantages of cellular mobile radio telephone services over the PSTN telephone services. (5)
Q.11 Write short notes on any TWO of the following :
(i) FAX.
(ii) Cable TV.
(iii) X.25 protocol. (7 + 7)
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