Test: Angle Modulation

# Test: Angle Modulation - Electronics and Communication Engineering (ECE)

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## 10 Questions MCQ Test - Test: Angle Modulation

Test: Angle Modulation for Electronics and Communication Engineering (ECE) 2023 is part of Electronics and Communication Engineering (ECE) preparation. The Test: Angle Modulation questions and answers have been prepared according to the Electronics and Communication Engineering (ECE) exam syllabus.The Test: Angle Modulation MCQs are made for Electronics and Communication Engineering (ECE) 2023 Exam. Find important definitions, questions, notes, meanings, examples, exercises, MCQs and online tests for Test: Angle Modulation below.
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Test: Angle Modulation - Question 1

### Match List-I with List-ll and select the correct answer using the codes given below the lists: List-I A. Pre-emphasis B. Varactor C. Voltage-controlled Oscillator D. De-emphasis List-ll 1. Voltage-variable capacitor 2. Uses a low-pass filter in a receiver 3. Frequency can be controlled by changing an external control voltage 4. Uses a high-pass filter in an FM transmitter. Codes:

Test: Angle Modulation - Question 2

### Assertion (A): There is less adjacent-channel interference in FM than in AM. Reason (R): Standard frequency allocation provide a guard band between commercial FM stations.

Test: Angle Modulation - Question 3

### The amount of frequency shift in FM is

Detailed Solution for Test: Angle Modulation - Question 3

Explanation:
Frequency modulation is a method of encoding information on a carrier wave by varying its frequency. In FM, the frequency of the carrier wave is varied in proportion to the amplitude of the modulating signal. This variation in frequency is what allows the transmission of information.
To understand why the frequency shift in FM is directly proportional to the amplitude of the modulating signal, let's break down the process:
1. Modulating Signal: The modulating signal is the signal that carries the information to be transmitted. It can be an audio signal, such as a voice or music, or any other type of signal.
2. Frequency Deviation: In FM, the frequency of the carrier wave is shifted above and below its center frequency. The extent of this frequency shift is known as the frequency deviation. It determines the range of frequencies that the carrier wave can vary.
3. Amplitude of the Modulating Signal: The amplitude of the modulating signal directly affects the frequency deviation in FM. When the amplitude of the modulating signal increases, the frequency deviation also increases.
4. Direct Proportionality: The relationship between the amplitude of the modulating signal and the frequency shift can be described as direct proportionality. This means that as the amplitude of the modulating signal increases, the frequency shift also increases proportionally. Similarly, if the amplitude decreases, the frequency shift will decrease accordingly.
In summary, the amount of frequency shift in FM is directly proportional to the amplitude of the modulating signal. This relationship allows for the transmission of information through varying frequencies, with the amplitude of the modulating signal determining the extent of the frequency shift.the change in the amplitude of modulating signal value.

Test: Angle Modulation - Question 4

Match List-l (Type of transmission) with List-l I (Applications) and select the correct answer using the codes given below the lists:
List-l
A. Wideband FM
B. AM
C. Narrowband FM
D. Vestigial sideband transmission
List-lI
2. Used for transmission of television signals
3. Used for high quality music transmission
4. Used for speech transmission (Police wireless, ambulance etc.)
Codes:

Test: Angle Modulation - Question 5

According to Carson’s rule, the bandwidth of FM wave is given by (Aω is the frequency deviation and ωm the modulating frequency)

Detailed Solution for Test: Angle Modulation - Question 5

According to Carson’s rule, the bandwidth of a single-tone wideband FM is
BW = 2(Δω + ωm)

Test: Angle Modulation - Question 6

Consider the following statements associated with angle modulations:
1. In FM, the frequency deviation is proportional to modulating frequency.
2. In PM, the frequency deviation is independent of modulating signal.
3. Amplitude of both FM and PM are constant.
4. It is possible to receive FM on a PM receiver and vice-versa.
5. Signal to noise ratio of PM is better than that of FM.
Which of the statements given above are correct?

Detailed Solution for Test: Angle Modulation - Question 6

• In FM, the frequency deviation is proportional only to the amplitude variation of the modulating signal and it is independent of modulating frequency fm. Hence, statement-1 is not correct.
• In PM, the frequency deviation increases with increase in modulating frequency fm and decreases with decrease in modulating frequency. Thus, frequency deviation in PM is proportional to modulating frequency. Hence, statement-2 is false.
• Statement-3 is correct.
• it is possible to receive FM on a PM receiver and PM on a FM receiver. Hence, statement-4 is correct.
• Signal to noise ratio of PM is inferior to that in FM. Hence, statement-5 is not correct.

Test: Angle Modulation - Question 7

We can obtain PM from frequency modulator by passing the modulating signal through a

Detailed Solution for Test: Angle Modulation - Question 7

A PM wave can be generated using a frequency modulator as shown in figure below:

Test: Angle Modulation - Question 8

Match List-l (Type of modulation) with List-II (Noise immunity) and select the correct answer using the codes given below the lists:

Detailed Solution for Test: Angle Modulation - Question 8

The noise immunity of FM is better than AM and PM while the noise immunity of PM is better than AM but worse than FM.

Test: Angle Modulation - Question 9

A FM wave is represented by the following equation:
v = 10 sin [5 x 10B t + 4 sin 1250 t]
Its maximum deviation is around.

Detailed Solution for Test: Angle Modulation - Question 9

Given, v = 10sin [5 x 108t + 4 sin 1250 t]
Comparing the above equation with the standard for FM given by

we have modulating frequency,

and modulation index,
mf = 4
∴ Maximum deviation,

Test: Angle Modulation - Question 10

In a FM system, the modulating frequency fm = 1 kHz, the modulating voltage Vm= 2 volt and the deviation is 6 kHz. If the modulating voltage is raised to 4 volt then what is the new deviation?

Detailed Solution for Test: Angle Modulation - Question 10

Given,
We know that,

or,

When, V'm = 4 V, the new deviation in frequency is

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