FACULT OF INFO
ACHELOR O SCIENC IN TELEC
BTC 120 Basic Dat and Voice Communica
DATE: 13th March 20
question 1 and any other t questions
tions carry 20 marks each
TIME: 2 H
QUESTIO 1 (COMPULSORY)
a. Match the followin functions t a layer of th OSI model
rocess-to-process message delivery
Provides user services s
such as e-mai and file tran
Transmission of bit stre across ph
wing multiple c
b. Answ the follow
The _____ is the phy
ysical path over which a me
A. Protocol B. Medium
(Each carries 1 mar
Which of the OSI layers is represent by frames?
A. Session B. Datalink
C. Transport D. Netwo
ss-to-process delivery of th entire message is the responsibility o the ______ he
A. Network B. Transport C. Applicatio D. Physic
Before dat can be trans
smitted, they must be trans
sformed to __
A. Periodic signals
C Aperiodic s
D . Low frequen sine wave
As frequen increases, the period _
A. Decreases B. Increases
Unipolar, bipolar, and p
polar encodin are types of _______ encoding.
C. Remains t same
PCM is an example of _______ conversion.
A. Digital-to-Digital B. Digit
AM and FM are examp of ______ conversio
A. Digital-to-Digital B. Digital-to-Analog
The sharing of a medium and its link by two or more devices is called _______. A. Modulation
C. Line discipline
Which multiplexing technique transmits analog signals?
D. (A) and (C)
In ________, we combine signals from different sources to fit into a larger bandwidth. A. Spread spectrum
B. Line coding
C. Block coding
None of the above
In modulo-2 arithmetic, we use the ______ operation for both addition and subtraction. A. XOR
ARQ stands for _______.
A. Automatic repeat quantization
D. None of them
B. Automatic Repeat Request
D. Acknowledge repeat request
________ is a type of transmission impairment in which the signal loses strength due to the resistance of the transmission medium.
A _________ sine wave is not useful in data communications; we need to send a _______ signal.
A. Composite; single-frequency
B. single-frequency; composite
D. None of the above
a. Why does impulse noise have more effect on digital signals rather than on analog signals? (4 marks)
b. What is the result of scrambling this sequence 11100000000000 using B8ZS? Assume the last most recent preceding 1 was positive.
c. What does dB measure? Let the energy strength at point 2 is 1/50th with respect to the point 1. Find out the attenuation in dB.
d. Two neighboring nodes (A and B) use a sliding window protocol with a 3-bit sequence number. As the ARQ mechanism, go-back-N is used with a window size of 4. Assuming A is transmitting and B is receiving, show the window positions for following succession of events: 2
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