Analog Communication Mcqs

Q:

The amount of frequency deviation in FM signal depends on ________

A) Modulating frequency B) Modulation Index
C) Amplitude of the modulating signal D) Carrier frequency
 
Answer & Explanation Answer: C) Amplitude of the modulating signal

Explanation: The amount of frequency deviation in the FM signal depends on amplitude of the modulating signal. So for any audio signal, as the loudness increases frequency deviation in carrier signal also increases. Frequency deviation helps in determining the bandwidth of FM signal.

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9
Q:

What is the function of frequency mixer in super heterodyne receiver?

A) Multiplication of incoming signal and the locally generated carrier B) Addition of incoming signal and the locally generated carrier
C) Amplification D) Filtering
 
Answer & Explanation Answer: A) Multiplication of incoming signal and the locally generated carrier

Explanation: The function of a frequency mixer in a super heterodyne receiver is that it mixes or multiplies the incoming modulated signal with the locally generated carrier in order to bring the incoming RF signal to a band of frequencies which can be processed easily.

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7
Q:

Vestigial side band signals are detected by ________

A) PLL detector B) Ratio detector
C) Square law demodulator D) Synchronous Detection
 
Answer & Explanation Answer: D) Synchronous Detection

Explanation: Vestigial side band signals are detected by Synchronous detection or coherent detection technique. The distortion in a VSB signal may be reduced by reducing the modulation index and increasing the width of VSB.

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13
Q:

Which of the following is AM demodulation techniques?

A) Square law demodulator and Envelope detector B) Ratio detector and PLL detector
C) PLL detector and Coherent detector D) PLL detector
 
Answer & Explanation Answer: A) Square law demodulator and Envelope detector

Explanation: AM signals are detected or demodulated using Square law demodulator and Envelope detector. The demodulator extracts the information from the received AM signal.

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11
Q:

USB (Upper Side Band) is the band of frequencies _________

A) below carrier frequency in AM spectrum B) above the carrier frequency in AM spectrum
C) includes the carrier frequency in AM spectrum D) is the center frequency
 
Answer & Explanation Answer: C) includes the carrier frequency in AM spectrum

Explanation: Upper Side Band is the band of frequencies above the carrier frequency that lies in AM spectrum. It is a part of the shifted spectrum obtained after amplitude modulation.

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13
Q:

Radio waves travel through ________

A) Coaxial Cable B) Wires
C) Optical fiber cable D) Electromagnetic waves
 
Answer & Explanation Answer: D) Electromagnetic waves

Explanation: Radio communication or wireless communication takes place through electromagnetic waves. The message is transmitted through open space via electromagnetic waves or radio waves.

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10
Q:

Analog signal may be converted into digital signal by ________

A) Filtering B) Mixing
C) Sampling D) Transducing
 
Answer & Explanation Answer: C) Sampling

Explanation: Conversion of an analog signal into digital signal converts a continuous time signal in the form of digits, by discretizing it. Thus, the conversion is done with the help of sampling technique.

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12
Q:

What is the effect on the transmitted power, if the modulation index changes from 0.8 to 1?

A) 0.1364 B) 0.239
C) 0.5 D) 0.3333
 
Answer & Explanation Answer: A) 0.1364

Explanation: Not available for this question

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