Tlcm 122: Telecommunications Fundamentals I Question Paper
Tlcm 122: Telecommunications Fundamentals I
Course:Bachelor Of Telecommunication And Information Engineering ()
Institution: Kabarak University question papers
Exam Year:2011
KABARAK UNIVERSITY
UNIVERSITY EXAMINATIONS
2011 ACADEMIC YEAR
FOR THE DEGREE OF BACHELOR OF TELECOMMUNICATION
TLCM 122: TELECOMMUNICATIONS FUNDAMENTALS I
DAY: MONDAY DATE: 06/08/2012
TIME: 2.00 – 4.00 P.M. STREAM: Y1S2
INSTRUCTIONS:
1. Answer ALL the questions in PART ONE and any TWO questions in PART TWO
2. Any extra questions answered will not be marked
PART ONE
Question One (30 marks)
a. Describe
i. The main source of internal noise in a copper based transmission medium. (2 marks)
ii. How an equalizer is used in a telecommunication network. (2 marks)
b. An amplifier has a gain of 67dB. If the power output from the amplifier is 45W,
calculate the power input to the amplifier. (2 marks)
c. Using a well labeled diagram, explain the operation of a simple simplex telephone circuit.
(6 marks)
d. Explain what is meant by sidetone. (2 marks)
e. Describe two disadvantages of a multistage crossbar switch as compared to a simple
crossbar switch. (4 marks)
f. Using a well labeled diagram explain how a TSI switch works. (6 marks)
g. Describe four functions of the control network of an exchange in the public switched
telephone network. (6 marks)
PART TWO
Question Two (20 marks)
a. Describe
i. Frequency modulation (2 marks)
ii. Amplitude shift keying (2 marks)
b. With regard to filters
i. Define the cut off frequency. (2 marks)
ii. Describe two advantages of using active filters in communication networks as compared
to using passive filters. (4 marks)
c. An analog signal has frequency components between 500Hz and 4300Hz. Determine the
frequency content of filtered signal if the analog signal is filtered using
i. A high pass filter with cut off frequency of 3500Hz.
ii. A band pass filter with cut off frequencies of 200Hz and 4700Hz.
(3 marks)
d. Can digital signals be frequency division multiplexed? Explain your answer. (3 marks)
e. 20 analog signals, each having frequency components between 350Hz and 3500Hz, are
frequency division multiplexed onto a medium with a bandwidth of 200 KHz. The
multiplexing process uses amplitude modulation. Determine the maximum size of the
guard band that can be used in the multiplexing process.
(4 marks)
Question Three (20 marks)
a. Describe
i. A self synchronizing code. (2 marks)
ii. How synchronization is implemented in a self synchronizing code. (2 marks)
b. Encode the following binary data 10111001 using
i. Alternate mark inversion code (2 marks)
ii. Non return to zero code (2 marks)
iii. Unipolar code (2 marks)
c. Between Manchester code and alternate mark inversion code, which code produces a
digital signal requiring more bandwidth (in Hertz) to transmit? Explain your answer.
(3 marks)
d. An analog signal with frequency components between 3400Hz and 7550Hz is digitized
using pulse code modulation. The signal is first sampled every 160 microseconds and
then quantized using 210 quantization levels.
i. Determine the bit rate of the resultant digital signal (4 marks)
ii. Is the resultant digital signal an accurate representation of the analog signal? Explain
your answer. (3 marks)
Question Four (20 marks)
a. Describe the time division multiplexing and demultiplexing processes. (3 marks)
b. What is the importance of synchronization in time division multiplexing? Explain how it
is implemented. (3 marks)
c. 25 digital signals are time division multiplexed, such that duration of each time slot in the TDM signal is 0.8 milliseconds.
i. Calculate the frame rate of the TDM signal. (2 marks)
ii. If the number of bits per slot is 16, calculate the bit rate of the TDM signal. (2 marks)
d. Describe basic rate integrated services digital network. (4 marks)
e. Show how the bit rates of 1.544Mbps and 2.048Mbps for T1 and E1 carriers respectively
are arrived at. (6 marks)
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