Comp 222-Telecommunications And Computers Question Paper
Comp 222-Telecommunications And Computers
Course:Bachelor Of Computer Science (It Telecommunication)
Institution: Kabarak University question papers
Exam Year:2010
KABARAK UNIVERSITY
UNIVERSITY EXAMINATIONS
2009/2010 ACADEMIC YEAR
FOR THE DEGREE OF BACHELOR OF COMPUTER SCIENCE
COURSE CODE: COMP 222
COURSE TITLE: TELECOMMUNICATIONS AND
COMPUTERS
STREAM: Y2S2
DAY: MONDAY
TIME: 2.00 – 4.00 P.M.
DATE: 02/08/2010
INSTRUCTIONS:
• Answer ALL the questions in PART ONE and any TWO questions in PART TWO.
PART ONE
QUESTION ONE (30 MARKS)
a. A transmission channel has a signal to noise ratio of 3090. The transmission
channel can transmit signals with frequencies between 4560 Hz and 9900 Hz.
Use the Shannon capacity formula to determine the theoretical highest data
rate for this channel. (3 marks)
b. An electromagnetic wave has a frequency of 1 GHz. Calculate its
i. Period (2 marks)
ii. Wavelength (2 marks)
c. An analog signal is converted to a digital signal using PCM. The analog
signal is first sampled at uniform intervals to give the following pulses.
Table A
Time
(seconds)
0 0.00005 0.00010 0.00015 0.00020 0.00025 0.00030 0.00035 0.00040 0.00045
Sample
amplitude
(volts)
1.4 4.2 5.1 8.8 11.9 15.3 18.7 22.5 24.1 26.6
The pulses are then quantized with a quantizer using the following quantization levels.
Table B
Quantization
levels
(volts)
0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30
The quantized pulses are then binary encoded by a binary encoder.
i. What is the sampling interval? (1 mark)
ii. Calculate the sampling rate (2 marks)
iii. Determine the quantized pulse level, for each of the sampled
pulses in table A. (5 marks)
iv. Calculate the bit rate of the resultant digital signal (4 marks)
d. What is digital transmission? (1 mark)
e. What is line coding? (1 mark)
f. For each of the following line codes; Manchester code and the unipolar code,
determine is they are;
i. Self synchronizing (2 mark)
ii. Has a residual DC component (2 mark)
g. For the following binary data
011001110101
Draw the
i. Manchester code (3 marks)
ii. Unipolar code (2 marks)
Page 3 of 4
PART TWO
QUESTION TWO (20 MARKS)
a. Describe
i. Frequency shift keying (4 marks)
ii. Frequency modulation (3 marks)
b. What is half duplex transmission? (1 mark)
c. What is full duplex transmission? (1 mark)
d. A transmission channel has a bandwidth of 5500 Hz. You are required to
provide full duplex transmission between two devices, with a guard band
of 500 Hz between the two directions. Amplitude shift keying is to be
used as the modulation scheme. Calculate
i. The bandwidth in Hz available for data transmission in
each direction (2 marks)
ii. The frequency of each carrier signal that is used for
modulation in each direction (3 marks)
iii. The baud rate in each direction (2 mark)
iv. The bit rate in each direction (2 marks)
v. The bit rate in each direction if 16 Quadrature Amplitude
Modulation is used instead (2 marks)
QUESTION THREE (20 MARKS)
a. What does the term burst error mean? (1 mark)
b. With regard to simple parity check what is meant by;
i. Odd parity (2 marks)
ii. Even parity (2 marks)
c. How many errors can be detected using simple parity check? (1 mark)
d. The following block of 16 bits is to be sent along with a checksum of
8 bits for error detection purposes.
0110010111110101
Use the checksum generator to generate the checksum bits, (3 marks)
e. A receiver receives the following pattern of bits.
101010010011111100011101
The bits consist of 16 data bits and eight checksum bits. Use the checksum
checker to determine if any errors occurred during transmission. (5 marks)
f. What is error control? (3 marks)
g. What is forward error correction? (3 marks)
Page 4 of 4
QUESTION FOUR (20 MARKS)
a. Time division multiplexing is used to multiplex ten lines each transmitting at
the rate of 1600 bits per second. The multiplexed signal is then transmitted on a
link whereby each time slot in the transmitted frames is 4 bits long. Calculate
i. The bit interval on each of the four lines (2 marks)
ii. The bit interval on the link carrying the TDM signal (2 marks)
iii. The duration of a time slot (2 marks)
iv. Duration of a frame (3 marks)
v. The bit rate of the multiplexed signal (2 marks)
b. 5 signals are frequency division multiplexed. Each signal has a bandwidth of
4200 Hz. A guard band of 200 Hz is used to separate the FDM bands. Calculate
the minimum bandwidth required for the FDM signal. (4 marks)
c. What is channelization? (2 marks)
d. Describe frequency division multiple access (FDMA) (3 marks)
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