# Analog Communications Questions and Answers – Filter Method

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This set of Analog Communications Multiple Choice Questions & Answers (MCQs) focuses on “Filter Method”.

1. In pulse code modulation bandwidth required is low.
a) True
b) False

Explanation: PCM stands for pulse code modulation. In PCM, the amplitude of the analog signal is discritised and converted into digital form for transmission of binary data. PCM usually requires a large bandwidth.

2. How do we eliminate the ghosts in the picture?
a) by using a long transmission line
b) by using a booster
c) by changing the orientation of antenna
d) by twisting the transmission line

Explanation: Change in antenna orientation helps in improving the reception of signals which further removes ghosts in the picture.

3. For getting maximum undistorted transmitted power in a carrier wave, the value of modulation should be _________
a) 1
b) 0.5
c) 0.2
d) 0.8

Explanation: The possible maximum value of modulation can be one. It signifies 100% modulation and thus at this value we have maximum undistorted transmitted power.
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a) True
b) False

Explanation: It is generally observed that a ship to ship communication suffers from fading. This problem can be avoided by using frequency diversity in which the components of a radio wave are received from different channels thus reducing the error that occurs in the transmission of a single frequency component.

5. What is the commercial channel bandwidth in a frequency modulated system?
a) 150 KHz
b) 250 KHz
c) 500 KHz
d) 900 KHz

Explanation: Bandwidth is the band of frequencies present within a given range of frequency. The standard commercial channel bandwidth for frequency modulated system is about 150 KHz.
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6. A buffer amplifier is a ________
a) double tuned amplifier
b) tuned amplifier
c) high gain DC amplifier
d) low gain DC amplifier

Explanation: Gain of an amplifier is its ability to increase the voltage at the input and produce the result at the output. A buffer amplifier is basically a high gain DC amplifier. It is basically used for transferring voltage from a high output impedance level to a low input impedance level circuit.

7. The direction of rotation of a CD is clockwise.
a) True
b) False

Explanation: CD stands for compact disk. The direction of rotation of Compact Disk is anticlockwise.

8. What is the full form of PAM?
a) Pulse Analog Modulation
b) Phase Analog Modulation
c) Pulse Amplitude Modulation
d) Phase Amplitude Modulation

Explanation: In communication, PAM stands for Pulse Amplitude Modulation. In PAM, the amplitude of the individual pulses of the message signal are varied in a specific time interval.

9. In a TV receiver antenna the length of reflector rod is _________
a) same as that of dipole
b) less than that of dipole
c) more than that of dipole
d) is half of that of dipole

Explanation: A dipole antenna is the one having its conductive wire rod equal to half the maximum wavelength of an antenna. The length of receiving antenna in a TV receiver must be more than that of dipole to get a better reception of signals.