7
MCQ (Single Correct Answer)
A male voice after modulation-transmission sounds like that of a female to the receiver. The problem is due to
A
poor selection of modulation index (selected $0< m< 1$ )
B
poor bandwidth selection of amplifiers
C
poor selection of carrier frequency
D
loss of energy in transmission.
8
MCQ (Single Correct Answer)
A basic communication system consists of
A. transmitter. B. information source. C. user of information. D. channel. E. receiver.
Choose the correct sequence in which these are arranged in a basic communication system.
A
ABCDE
B
BADEC
C
BDACE
D
BEADC
9
MCQ (Single Correct Answer)
Identify the mathematical expression for amplitude modulated wave
A
$A_c \sin \left[\left\{\omega_c+k_1 V_m(t)\right\} t+\phi\right]$
B
$A_c \sin \left\{\omega_c t+\phi+k_2 V_m(t)\right\}$
C
$\left\{A_c+k_2 V_m(t)\right\} \sin \left(\omega_c t+\phi\right)$
D
$A_c V_m(t) \sin \left(\omega_c t+\phi\right)$
10
MCQ (Multiple Correct Answer)
An audio signal of 15 kHz frequency cannot be transmitted over long distances without modulation, because
A
the size of the required antenna would be at least 5 km which is not convenient
B
the audio signal can not be transmitted through sky waves
C
the size of the required antenna would be at least 20 km , which is not convenient
D
effective power transmitted would be very low, if the size of the antenna is less than 5 km
11
MCQ (Multiple Correct Answer)
Audio sine waves of 3 kHz frequency are used to amplitude modulate a carrier signal of 1.5 MHz . Which of the following statements are true?
A
The side band frequencies are 1506 kHz and 1494 kHz
B
The bandwidth required for amplitude modulation is 6 kHz
C
The bandwidth required for amplitude modulation is 3 MHz
D
The side band frequencies are 1503 kHz and 1497 kHz