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CORK INSTITUTE OF TECHNOLOGY
INSTITIÚID TEICNEOLAÍOCHTA CHORCAÍ
Semester 2 Examinations 201 1 /1 2
Module Title: Telecommunications
Module Code: ELTR
School: MECHANICAL, ELECTRICAL & PROCESS ENGINEERING
Programme Titles: Bachelor of Engineering in Electronic Engineering, Year 2 Bachelor of Engineering in Electronic Systems Engineering, Year 2
Programme Codes: EELXE_7_Y EELES_8_Y
External Examiner(s): Dr. A. Donnellan Mr I. Kennedy Internal Examiner: Mr M. O’Gorman
Instructions: Answer Question 1 and TWO other questions. Question 1 (worth 40 marks) is compulsory. Questions 2, 3, and 4 are each worth 30 marks.
Duration: 2 Hours
Sitting: Autumn 201 2
Requirements for this examination: N/A
Note to Candidates: Please check the Programme Title and the Module Title to ensure that you are attempting the correct examination paper. If in doubt please contact an Invigilator.
COMPULSORY QUESTION
Q.1 (a) If the envelope of an AM waveform varies between a maximum of ±8 V olts and a minimum of ±2 V olts, determine; (i) V c, the maximum carrier signal amplitude, [3 Marks] (ii) V m, the maximum modulating signal amplitude, [3 Marks] (iii) m, the modulation factor. [4 Marks]
(b) Assuming that a dash occurs with half the probability of a dot in Morse code, calculate the following:- (i) The information in a dot, [3 Marks] (ii) The information in a dash, [3 Marks] (iii) The entropy of the code. [4 Marks]
(c) Briefly describe what is meant by time division multiplexing (TDM). [10 Marks]
(d) Briefly describe what is meant by the term Nyquist sampling rate. [10 Marks]
CHOOSE TWO QUESTIONS FROM Q.2, Q.3, OR Q.4.
Q. 2 (a) Describe the process of sampling and quantisation of a continuous information signal when used as the first step in the generation of a pulse code modulated (PCM) waveform. [15 Marks]
(b) Explain how quantisation noise occurs, and why the signal-to-quantisation noise ratio, S/Nq, deteriorates for low-level signals. [8 Marks]
(c) Explain what is meant by non-linear quantisation , and describe its effect on the S/Nq of voice and telephone channels. [7 Marks]
