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Tlcm 211:Telecommunications Fundamentals December 2010 Question Paper

Tlcm 211:Telecommunications Fundamentals December 2010

Course:Bachelor Of Science In Telecommunications

Institution: Kabarak University question papers

Exam Year:2010

KABARAK UNIVERSITY
UNIVERSITY EXAMINATIONS
2010/2011 ACADEMIC YEAR
FOR THE DEGREE OF BACHELOR OF SCIENCE IN
TELECOMMUNICATIONS
COURSE CODE: TLCM 211

INSTRUCTIONS:
Answer ONE question from PART ONE and any THREE questions from PART TWO

QUESTION ONE (20 MARKS)

a. The basic building block of a Strowger switching system is the selector. Name and
describe the two types of selectors used in a Strowger switching system. (3 marks)
b. What is the function of the guard circuit; one of the control circuits found on selectors
in a Strowger system. (1 mark)
c. For a 4 digit Strowger exchange (exchange for telephone number with four digits).
i. How many group selector stages does it have (1 mark)
ii. Determine which selector is controlled by which digit in the 4 digit number and
describe how the selector is controlled. (4 marks)
d. Give two disadvantages of pulse dialing. (2 marks)
e. Describe how multi frequency dialing works. (2 marks)
f. Give the main disadvantage of a crossbar switch (1 mark)
g. Give the main disadvantage of time slot interchanger switch (1 mark)
h. How does a TST multistage switch eliminate the disadvantages named in f and g
above? (2 marks)
i. Name and describe three services that are made available by the use of an electronic
exchange (3 marks)

QUESTION TWO (10 MARKS)
a. In a laser diode what is meant by population inversion and why is it required
(1 mark)
b. Explain why laser diodes are more suited for single mode propagation as compared to
LEDs. (2 marks)
c. Give three reasons why LEDs and laser diodes are suitable for fiber optic transmission.
(3 marks)
d. Explain the operation of a p-i-n photodiode (2 marks)
e. What is the advantage of an avalanche photodiode as compared to a p-i-n photodiode?
(1 mark)
f. Give two disadvantages of fiber optic communications (1 mark)

QUESTION THREE (10 MARKS)

a. Give the main reason for having three satellite orbits (1 mark)
b. Describe how the GPS network works (2 marks)
c. In satellite communications what is a meant by a hop and a roundtrip? (1 mark)
d. LEO satellites are preferred in providing broadband networks as compared to GEO
satellites. Give two reasons why this is so. (2 marks)
e. Name the three main parts of a satellite. (1 mark)
f. What is meant by horizontally and vertically polarized electromagnetic waves?
(1 mark)
g. Describe a resonant dipole antenna. (1 mark)
h. What is the advantage of using a parabolic dish? (1 mark)

QUESTION FOUR (10 MARKS)

a. Describe the three main ways of making a VOIP call. (3 marks)
b. What is a peep to peer VOIP call? (1 mark)
c. What is the main advantage of VOIP over traditional forms of telephony? (1 mark)
d. Describe the frequency reuse principle used in cellular networks and explain why it is
used. (3 marks)
e. In cellular networks;
i. What is meant by handoff. (1 marks)
ii. Describe the two types of handoff. (1 mark)

QUESTION FIVE (10 MARKS)

a. Briefly describe
i. Amplitude modulation (1 mark)
ii. Frequency modulation (1 mark)
iii. Phase modulation (1 mark)
b. Pulse code modulation consists of three steps. Briefly describe these steps.
(2 marks)
c. Describe the frequency division multiplexing and demultiplexing processes.
(3 marks)
d. A transmission medium has a bandwidth of 15000 Hz. How many signals each with a
bandwidth of 350 Hz can be frequency division multiplexed on the medium when a
guard band of 60 Hz is used? (2 marks)

Tlcm 211:Telecommunications Fundamentals December 2010 Question Paper

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