Communication Systems MCQ Questions Answers Electronics Engineering

Communication Systems Electronics & Communication Engineering MCQ Questions Answers


1) 13 dBm is equivalent to

a) 2 mW

b) 20 W

c) 20 Mw

d) 2 MW

View Answer
Option – c)

2) A superheterodyne receiver with an IF of 450 kHz is tuned to a signal at 1200 kHz. The image frequency is

750 kHz

900 kHz

1650 kHz

2100 kHz

View Answer
Option – d)

3) MCVF telegraphy uses

a) SSB techniques

b) Pulse modulation

c) out-of band signaling

d) FM

View Answer
Option – d)

4) If a FET is used as the first AF amplifier in a transistor receiver, this will have the effect of

improving the effectiveness of the AGC

reducing the effect of negative-peak clipping

reducing the effect of noise at low modulation depths

improving the selectivity of the receiver

View Answer
Option – b)

5) Which of the following pulse modulation is analog ?

a) PCM

b) Differential PCM

c) PWM

d) Delta

View Answer
Option – c)

6) A 1 MHz sinusoidal carrier is amplitude modulated by a symmetrical square wave of period 100 µsec. Which of the following frequencies will not be present in the modulated signal?

(a) 990 kHz

(b)1010 kHz

(c) 1020 kHz

(d)1030 kHz

View Answer
Option – c)

7) The code which provides for parity check is

a) Baudot

b) ASCII

c) EBCDIC

d) Excess-3

View Answer
Option – b)

8) What is the SNR improvement with FSK  over ASK in most types of noise environment ?

a) 200 to 300dB

b) 3 to 4dB

c) 10 to 12Db

d) 0Db

View Answer
Option – b)

9) An angle-modulation signal is given by ?(?) = cos(2? × 2 × 106 ? + 2? × 30 sin 150? + 2? × 40 cos 150?) The maximum frequency and phase deviations of s(t) are

(a) 10.5KHz, 140π rad

(b)6 KHz, 80π rad

(c) 10.5 KHz, 100π rad

(d)7.5 KHz, 100π rad

View Answer
Option – d)

10) In FDM systems used for telephone, which modulation scheme is adopted ?
a) AM
b) DSB-SC

c) SSB-SC
d) FM

View Answer
Option – c)