TMA 1 Telecommunication Principles 2016

8/18/2019 TMA 1 Telecommunication Principles 2016

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TEE213/05 Telecommunication Principles Sem1/2016

TEE 213/05

Telecommunication Principles

Tutor-marked Assignment 1

Evidence of plagiarism or collusion will be taken seriously and the University

regulations will be applied fully. You are advised to be familiar with the University’s

definitions of plagiarism and collusion.

Instructions:

1. This is an individual assignment. No duplication of work will be tolerated.

Any plagiarism or collusion may result in disciplinary action in addition to

ZERO mark being awarded to all involved.

2.

You are required to submit your answers through the Online Assignment

Submission (OAS) system and it is your responsibility to submit your TMA

correctly and timely. OAS system doesn’t allow re-submission of assignment.

3. The total marks for TMA 1 is 100% and contributes 25% towards the total

grade. Marks will be awarded for correct working steps and answer.

4. TMA 1 covers topics from Unit 1 and Unit 2.

5.

TMA 1 contains five questions. Answer all parts in English.

6. Your assignment must be word processed in Time New Roman text font size

12 with 1.5 line spacing. Any additional appendices or attachments must be

placed at the end of the submitted document.

7. Include a cover page for your TMA including name, student ID, email

address, course name and code.

8.

You are highly encouraged to passage your TMAs to the Turnitin system

before submission, to encourage honest academic writing and it is not

mandatory except for Project courses.


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Question 1

(a) With the aid of diagrams, explain TWO (2) differences between simplex, half

duplex and full duplex mode of communication.

[9 marks]

(b) A 10kW carrier wave is amplitude modulated at 80% depth of modulation by

a sinusoidal modulating signal.

Determine:

i. the sideband power

[4 Marks]

ii. the total power

[4 Marks]

iii.

the transmission efficiency of the AM wave

[3 Marks]

Question 2

(a) A carrier wave of frequency 10MHz and peak value 10V is amplitude

modulated by a 5kHz of amplitude 6V.

Answer the following questions:

i. Determine the modulation factor.

[2 Marks]

ii. Determine the sideband frequencies.

[2 Marks]

iii. Determine the amplitude of sideband components.

[2 Marks]

iv. Draw the frequency spectrum.

[4 Marks]

(b) A frequency modulated wave is given by the equation:

= 12cos6 × 108 + 5 sin 1250 Find:

i. the carrier frequency.

[2 Marks]

ii. the signal frequency.

[2 Marks]iii. the modulation index.

[2 Marks]

iv. the maximum frequency deviation.

[2 Marks]

v. the power dissipated by the FM wave in 10Ω resistor.

[2 Marks]


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Question 3

(a) A radio station, 1280AM, is conducting a monthly test of the Emergency Alert

System. The test begins with an annoying sound comprised of two pure tones

at 853Hz and 960Hz. The signal being broadcast has exactly five frequency

components.

The signal could be written as follows:

vAM(t) = v1 sin(2π f 1 t) + v2 sin(2π f 2 t) + v3 sin(2π f 3 t) + v4 sin(2π f 4 t) + v5

sin(2π f 5 t) [V]

Find the five frequencies that comprise the AM signal being broadcast. The

carrier frequency and the two sidebands for each of the two tones will be

involved.

[5 marks]

(b) Consider a FM modulator with modulation index m = 5, modulating signal

vm = 2 sin(2π5k t), and an unmodulated carrier frequency f c = 400 kHz, answer

the following questions:

i. Number of sets of significant sidebands

[2 Marks]

ii. Sideband amplitudes

[9 Marks]

iii. Draw the output frequency spectrum

[4 Marks]

[Hint: refer to Bessel Table]

Question 4

(a) Draw Amplitude – Shift Keying (ASK) signal and Frequency – Shift Keying

(FSK) signal for the following data: 101010001101.

[10 Marks]

(b) In general, digital signals are stored after the analog-digital (A/D) conversion

in a digital memory, e.g. the main memory. In order to convert digital signals

back to analog signals, digital-analog (D/A) converters are needed. This

relationship is illustrated in Figure 1:

Figure 1

http://en.wikipedia.org/wiki/Emergency_alert_system#Technical_concepthttp://en.wikipedia.org/wiki/Emergency_alert_system#Technical_concepthttp://en.wikipedia.org/wiki/Emergency_alert_system#Technical_concepthttp://en.wikipedia.org/wiki/Emergency_alert_system#Technical_concept


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i. We consider ′ the recovered, analog signal after the sampling and

quantization. Why is an errorless reconstruction of the analog signal

not possible even assuming ideally working components?

[2 Marks]

ii. Name two advantages of digital signals over analog signals.

[8 Marks]

Question 5

(a) The signal shown in Figure 2 was sampled and quantized. The variance of

quantization error is 2.0833. Compute the following:

Smax=30

Smin=-10

0

Δ

Figure 2

i. Total number of levels.

[Hint: σ2 = △2/12][3 Marks]

ii. The number of bits required to represent each sample.

[3 Marks]

(b) Assume that the word “Freddy” needs to be transmitted through a transmission

line. Using the attached ASCII table in the appendix, answer the following

questions:

i. How many bits are needed by this transmission?

[6 marks]

ii. Using the odd parity for the VRC and even parity for LRC, compute

the VRC and LRC for this transmission.

[8 marks]


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Appendix

Bessel Table


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ASCII Table


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ASCII Table

END OF TMA 1

TMA 1 Telecommunication Principles 2016

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