EASY
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What are the applications of amplitude modulation?

Important Questions on Communication Systems

HARD

A diode detector is used to detect an amplitude modulated wave of 60% modulation  by using a condenser of capacity 250 pico farad in parallel with a load resistance of 100 kilo ohm. Find the maximum modulated frequency which could be detected by it.

MEDIUM
A message signal of frequency 100 MHz and peak voltage 100 V is used to execute amplitude modulation on a carrier wave of frequency 300 GHz and peak voltage  400 V . The modulation index and difference between the two side band frequencies are:
EASY
A signal of frequency 3kHz is amplitude modulated on a carrier wave of frequency 2.5 MHz. The upper and lower sideband frequencies in the resultant signal are
HARD
The modulation frequency of an AM radio station is 250 kHz, which is 10% of the carrier wave. If another AM station approaches you for license what broadcast frequency will you allot?
HARD

A signal of 5 kHz frequency is amplitude modulated on a carrier wave of frequency 2 MHz. The frequencies of the resultant signal is/are:

EASY
If the maximum and the minimum amplitudes of an amplitude modulated wave are 25 V and 5 V respectively, then the modulation index is
EASY
In amplitude modulation of audio frequency 700Hz, the appropriate carrier frequency to be used is
EASY
For signal transmission, modulation is necessary
EASY
Choose the correct statement:
HARD
A modulated signal Cmt has the form Cmt=30sin300πt+10 cos200πt-cos400πt. The carrier frequency fc , the modulating frequency (message frequency) fm , and the modulation index μ are respectively given by :
EASY
For an amplitude modulated wave, the maximum amplitude is found to be 12 V while the minimum amplitude is found to be 4 V. The modulation index μ will be
EASY
In amplitude modulation, the sinusoidal carrier frequency used is denoted by ωc and the signal frequency is denoted by ωm . The bandwidth Δωm of the signal is such that Δωmωc. Which of the following frequencies is not contained in the modulated wave?
EASY
A message signal of frequency 10 kHz and peak value of 10 volts is used to moderate a carrier of frequency 1 MHz and peak voltage 20 volts. The modulation index and side bands produced are
MEDIUM
A signal of frequency 20kHz and peak voltage 10 V is used in the amplitude modulation of a carrier wave of frequency 0.5MHz and peak voltage 20 V. Then the ratio of the frequencies of upper side band to the lower side band is
EASY
If a message signal of frequency fm is amplitude modulated with a carrier signal of frequency fc and radiated through an antenna, the wavelength of the corresponding signal in air is
EASY
Amplitude modulation is the process of
MEDIUM
What modulation index and side bands are produced when a message of frequency 10KHz and peak voltage of 10 volts is used to modulate a carrier frequency of 1MHz and peak voltage of 20 volts?
EASY
In a CE transistor amplifier, the audio signal voltage across the collector resistance of 2  is 2 V, if the base resistance is 1  and the current amplification of the transistor is 100 then the input signal voltage is
MEDIUM
A signal of frequency 20 kHz and peak voltage of 5 Volt is used to modulate a carrier wave of frequency 1.2 MHz and peak voltage 25 Volts. Choose the correct statement.