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Basic Voice And Data Communications Question Paper
Basic Voice And Data Communications
Course:Bachelor Of Science In Telecommunications
Institution: Strathmore University question papers
Exam Year:2011
STRATHMORE UNIVERSITY
FACULTY OF INFORMATION TECHNOLOGY
Bachelor of Science in Telecommunications
END OF SEMESTER EXAMINATION
BTC 1202: BASIC VOICE AND DATA COMMUNICATIONS
DATE: 23rd March, 2011 TIME: 2HRS
INSTRUCTIONS: - Answer Question ONE and any other TWO questions.
QUESTION ONE (20 MARKS)
a)
i) What three disciplines are involved in data communications? (3 Marks)
ii) What are the three major motivations for data communications? (3 Marks)
iii) What are the conceptual pieces of a data communications system? (3 Marks)
b)
i) Which piece of a data communications system handles analog input? Explain. (2 Marks)
ii) Which piece of a data communications system prevents transmission errors from corrupting
data? (1 Mark)
iii) iii) Compute the Hamming distance for the following pairs: (0000, 0001), (0101, 0001), (1111,
1001), and ( 0001, 1110). (2 Marks)
c)
i) Explain, with the aid of a well labeled diagram, what the Fourier analysis of a composite
wave produces. (3 Marks)
ii) What is a codeword, and how is it used in forward error correction? (3 Marks)
2
QUESTION TWO (20 MARKS)
a)
i) Use suitable examples to explain why sine waves are fundamental to data communications.
(3 marks)
ii) State and describe the four fundamental characteristics of a sine wave. (4 Marks)
iii) What is the analog bandwidth of a signal? (2 Marks)
c)
i) What is the definition of baud? (2 Marks)
ii) Suppose an engineer increases the number of possible signal levels from two to four. How
many more bits can be sent in the same amount of time? Explain. (4 Marks)
iii) Explain why framing and synchronization are important in a TDM system. (3 Marks)
iv) Define the concept of Hamming distance. (2 Marks)
QUESTION THREE (20 MARKS)
a)
i) If someone shows you a copper cable and claims that it is an “OC-12 circuit”, what error have
they made? What is the correct name they should have used? (3 Marks)
ii) What is a synchronization error? (2 Marks)
iii) Why do some coding techniques use multiple signal elements to represent a single bit? What
aspect of a signal does the Manchester Encoding use to represent a bit? (4 Marks)
b)
i) What is the chief advantage of a Differential Manchester Encoding? (2 Marks)
ii) When converting an analog signal to digital, what step follows sampling? (1 Mark)
c)
i) Differentiate between lossy and lossless compressions. Give one application of each.
(4 Marks)
ii) Explain how transmission errors affect data. Explain any two such errors, giving possible
remedial approaches adopted to curb them. (4 Marks)
3
QUESTION FOUR (20 MARKS)
a)
i) List and explain the three main sources of transmission errors. (6 Marks)
ii) Explain the relationship between bandwidth, signal levels, and data rate. (3 Marks)
b)
i) 7.23 If a system has an average power level of 100, an average noise level of 33.33, and a
bandwidth of 100 MHz, what is the effective limit on channel capacity? (4 Marks)
ii) If a system has an input power level of 9000, and an output power level of 3000, what is the
difference when expressed in dB? (3 Marks)
c)
i) What is the chief characteristic of asynchronous transmission? (2 Marks)
ii) In a burst error, how is burst length measured? (2 Marks)
QUESTION FIVE (20 MARKS)
a)
i) List the three basic types of analog modulation. (3 Marks)
ii) If a telephone system can be created with a signal-to-noise ratio of 40 dB and an analog
bandwidth of 3000 Hz, how many bits per second could be transmitted? (4 Marks)
b)
i) What are the characteristics of a CRC? (3 Marks)
ii) What is propagation delay? (1 Mark)
iii) When using a synchronous transmission scheme, what happens when a sender does not
have data to send? (2 Marks)
c)
i) What are the four basic types of multiplexing? (2 Marks)
ii) What is a guard band? (1 Mark)
iii) Explain how a range of frequencies can be used to increase data rate. (2 Marks)
iv) What is the difference between guided and unguided transmission? (2 Marks
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