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CORK INSTITUTE OF TECHNOLOGY
INSTITIÚID TEICNEOLAÍOCHTA CHORCAÍ
Semester 2 Examinations 2010/
Module Title: Telecommunications
Module Code: ELTR
School: ELECTRICAL & ELECTRONIC ENGINEERING
Programme Titles: Bachelor of Engineering in Electronic Engineering, Year 2 Bachelor of Engineering (Honours) 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: Summer 2011
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) Briefly describe what is meant by the term Nyquist sampling rate. [10 Marks]
(b) If the envelope of an AM waveform varies between a maximum of ±6 V P-P and a minimum of ±2 V P-P, 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]
(c) Briefly describe what is meant by time division multiplexing (TDM). [10 Marks]
(d) Calculate the average information (entropy), in binits/letter, for the English language, assuming (wrongly!) that each of the 26 letters of the alphabet occurs with equal likelihood. [10 Marks]
CHOOSE TWO QUESTIONS FROM Q.2, Q.3, OR Q.4.
Q. 2 (a) Draw eight cycles of a square wave clock on graph paper and allocate the following binary data sequence to the eight clock periods:-
Encode the data into each of the following codes:- (i) Non-return to zero (NRZ), (ii) Return to zero (RZ),
(iii) Bi-Phase (Bi- ) Manchester,
(iv) Alternate Mark Inversion (AMI). [20 Marks] (b) For long random data sequences, indicate which of the four codes in (a) provides; (i) The smallest dc component, (ii) The highest transition density. [10 Marks]
