Amplitude Modulation

This is an MCQ-based quiz on Amplitude Modulation.

This includes Varactor diode, High pass Filter, Zener diode, Low pass filter, Carrier frequency, Upper sideband frequency, Lower sideband frequency.

Start Quiz

Why is AM used for broadcasting in the communication systems?

Its use avoids receiver complexity It is more immune to other modulation systems It requires less transmitting power No noise disturbances

What happens when the amplitude of the modulating signal is greater than the amplitude of the carrier?

Decay Distortion Amplification Attenuation

What is the effect of distortion?

Total information loss Error information Attenuated information Amplified information

What is the circuit used for producing AM called?

Modulator Transmitter Receiver Duplexer

The ratio between the modulating signal voltage and the carrier voltage is called?

Amplitude modulation Modulation frequency Modulation index Ratio of modulation

What is the modulating signal voltage if the maximum and the minimum voltages on the wave was observed to be 5.9v and 1.2v respectively?

2.35v 2.12v 1.85v 3.21v

Which of the following modulating signal voltage would cause over-modulation on a carrier voltage of 10v?

9.5 9.99 10 12

What is the modulation index value if Vmax=5.9v and Vmin=1.2v?

0.5 0.662 0.425 0.14

What is the condition for greatest output power at the transmitter without distortion?

Modulating signal voltage > Carrier voltage Modulating signal voltage < Carrier voltage Modulating signal voltage = Carrier voltage Modulating signal voltage = 0

Standard intermediate frequency used for AM receiver is

455 MHz 455 KHz 455 Hz None of the above

In the TV receivers, the device used for tuning the receiver to the incoming signal is

Varactor diode High pass Filter Zener diode Low pass filter

The modulation technique that uses the minimum channel bandwidth and transmitted power is

FM DSB-SC VSB SSB

Calculate the bandwidth occupied by a DSB signal when the modulating frequency lies in the range from 100 Hz to 10KHz.

28 KHz 24.5 KHz 38.6 KHz 19.8 KHz

In Amplitude Demodulation, the condition which the load resistor R must satisfy to discharge capacitor C slowly between the positive peaks of the carrier wave so that the capacitor voltage will not discharge at the maximum rate of change of the modulating wave (W is message bandwidth and ω is carrier frequency, in rad/sec) is

RC < 1/W RC > 1/W RC < 1/ω RC > 1/ω

An AM broadcast station transmits modulating frequencies up to 6 kHz. If the AM station is transmitting on a frequency of 894 kHz, the values for maximum and minimum upper and lower sidebands and the total bandwidth occupied by the AM station are:

900 KHz, 888 KHz, 12 KHz 894 KHz, 884 KHz, 12 KHz 894 KHz, 888 KHz, 6 KHz 900 KHz, 888 KHz, 6 KHz

Calculate the depth of modulation when a transmitter radiates a signal of 9.8KW after modulation and 8KW without modulation of the signal.

80% 67% 50% 100%

Calculate the power in one of the side band in SSBSC modulation when the carrier power is 124W and there is 80% modulation depth in the amplitude modulated signal.

89.33 W 64.85 W 79.36 W 102 W

Calculate the frequencies available in the frequency spectrum when a 2MHz carrier is modulated by two sinusoidal signals of 350Hz and 600Hz.

2000.35, 1999.65 and 2000.6, 1999.4 1999.35, 1999.65 and 2000.6, 2000.4 2000.35, 2000.65 and 2000.6, 2000.4 1999.35, 1999.65 and 1999.6, 1999.4

Calculate the power saved in an Amplitude Modulated wave when it is transmitted with 45% modulation – Without carrier – Without carrier and a sideband

90%, 95% 82%, 91% 82%, 18% 68%, 16%

Which one of the following statements regarding compandor is FALSE?

It compresses the higher-amplitude parts of a signal before modulation and expands them back to normal again after demodulation. It gives preferential treatment to the weaker parts of the signal For weaker signals it gives a poor ratio of signal strength to quantizing error Weaker signals, traverse more quantum steps than they would do otherwise and so quantizing error is reduced.

Quiz/Test Summary

Title: Amplitude Modulation

Questions: 20

Contributed by:

Diego Tue, Mar 29, 2022 10:58 AM UTC

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