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Important Questions on Communication Systems

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Physics>Modern Physics>Communication Systems>Modulation

In amplitude modulation of audio frequency

700 Hz

, the appropriate carrier frequency to be used is

HARD

Physics>Modern Physics>Communication Systems>Modulation

A modulated signal

C_{m} (t)

has the form

C_{m} (t) = 30 \sin 300 π t + 10 (\cos 200 π t - \cos 400 π t) .

The carrier frequency

f_{c}

, the modulating frequency (message frequency)

f_{m ,}

and the modulation index

μ

are respectively given by :

MEDIUM

Physics>Modern Physics>Communication Systems>Modulation

A message signal of frequency

100 M H z

and peak voltage

100 V

is used to execute amplitude modulation on a carrier wave of frequency

300 G H z

and peak voltage

400 V

. The modulation index and difference between the two side band frequencies are:

EASY

Physics>Modern Physics>Communication Systems>Modulation

If the maximum and the minimum amplitudes of an amplitude modulated wave are

25 V

and

5 V

respectively, then the modulation index is

HARD

Physics>Modern Physics>Communication Systems>Modulation

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

Physics>Modern Physics>Communication Systems>Modulation

A signal of frequency

20 kHz

and peak voltage

10 V

is used in the amplitude modulation of a carrier wave of frequency

0.5 MHz

and peak voltage

20 V

. Then the ratio of the frequencies of upper side band to the lower side band is

EASY

Physics>Modern Physics>Communication Systems>Modulation

In a

CE

transistor amplifier, the audio signal voltage across the collector resistance of

2 kΩ

2 V

, if the base resistance is

1 kΩ

and the current amplification of the transistor is

100

then the input signal voltage is

EASY

Physics>Modern Physics>Communication Systems>Modulation

If a message signal of frequency

f_{m}

is amplitude modulated with a carrier signal of frequency

f_{c}

and radiated through an antenna, the wavelength of the corresponding signal in air is

EASY

Physics>Modern Physics>Communication Systems>Modulation

In amplitude modulation, the sinusoidal carrier frequency used is denoted by

ω_{c}

and the signal frequency is denoted by

ω_{m}

. The bandwidth

(Δ ω_{m})

of the signal is such that

Δ ω_{m} ≪ ω_{c}

. Which of the following frequencies is not contained in the modulated wave?

MEDIUM

Physics>Modern Physics>Communication Systems>Modulation

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.

EASY

Physics>Modern Physics>Communication Systems>Modulation

Identify the correct statement among the following.

EASY

Physics>Modern Physics>Communication Systems>Modulation

In amplitude modulation

EASY

Physics>Modern Physics>Communication Systems>Modulation

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

Physics>Modern Physics>Communication Systems>Modulation

A signal of frequency

3 kHz

is amplitude modulated on a carrier wave of frequency

2.5 MHz .

The upper and lower sideband frequencies in the resultant signal are

EASY

Physics>Modern Physics>Communication Systems>Modulation

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

Physics>Modern Physics>Communication Systems>Modulation

What modulation index and side bands are produced when a message of frequency

10 KHz

and peak voltage of

10

volts is used to modulate a carrier frequency of

1 MHz

and peak voltage of

20

volts?

EASY

Physics>Modern Physics>Communication Systems>Modulation

For signal transmission, modulation is necessary

EASY

Physics>Modern Physics>Communication Systems>Modulation

Choose the correct statement:

HARD

Physics>Modern Physics>Communication Systems>Modulation

The modulation frequency of an

A M

radio station is

250 kHz,

which is

10 %

of the carrier wave. If another

A M

station approaches you for license what broadcast frequency will you allot?

HARD

Physics>Modern Physics>Communication Systems>Modulation

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:

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Important Questions on Communication Systems

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