DAR ES SALAAM INSTITUTE OF TECHNOLOGY

Computer Studies Department

Class: OD 05 Computer & Telecom

Module: Signal & Data Processing Circuits

Module Code:COED 202

Duration: 2.30 hrs

Instructions: Attempt all questions in section A and any two questions from

section B

Students are permitted to bring into the examination room: pens,

pencils, highlighters, erasers, sharpeners and rulers.

Students are NOT permitted to bring into the examination room:

blank sheets of paper and/or white out liquid/tape.

Calculator is allowed in this examination.

Marks are clearly shown in each question.

All written responses must be in English.

Section A: Attempt ALL questions ( 40 Marks)

1. What is the main difference between a dedicated and a leased

line used to connect terminal devices to computers or to other

terminals via a wide area network? (marks 2)

2. Briefly explain the following transmission mode terms and

state at least one example :- ( 6 marks)

a. Simplex transmission

b. Half-duplex transmission

c. Full-duplex transmission

3. What is the difference between serial and parallel

transmission? Why do most communications systems use

serial transmission? (4 marks)

4. With short notes explain the function of the following

transmission devices

a. Repeater ( 2 Marks)

b. Modem ( 2 Marks)

5. Define the following terms

a. Amplitude Modulation (AM) ( 2 Marks)

b. Frequency Modulation (FM) ( 2 Marks)

c. Frequency-Shift Keying (FSK) ( 2 Marks)

d. Phase-Shift Keying (PSK) ( 2 Marks)

e. Modulation Index ( 2 Marks)

6. Briefly explain the following basic function of the receiver:-

a. Reception ( 2 Marks)

b. Selection( 2 Marks)

c. Detection( 2 Marks)

d. Reproduction ( 2 Marks)

7. What is primary advantage of using Transceiver rather than a

separate transmitter? ( 2 Marks)

8. Name 4 types of transmission codes. ( 2 Marks)

9. What are the causes of transmission errors? Mention 2

causes. ( 2 Marks)

Section B

Choose any two questions

10. An AM transmitter radiates 2 kW when the carrier is

unmodulated and 2.25 kW when the carrier is modulated.

When a second modulating signal is applied giving a

modulation factor of 0.4, calculate the total radiated power

with both signals applied. ( 10 Marks)

11. Given the following AM transmitter block diagram, explain the

functions of at least 5 components shown in the block

diagram below. (10 marks)

12. Briefly explain the following error detection and correction techniques and explain where are they used:- ( 10 Marks)a. Parity checkingb. Geometric codes