Find real questions from previous competitive exam papers with answers and solutions.
Leave the keyword blank to browse saved questions for your selected exam, newest papers first. Add a keyword, year or topic to narrow the results.
Browse complete papersWhat is the transmission frequency range of FM radio?
28-58 MHz
88-108 MHz
58-88 MHz
108-128 MHz
Correct answer
28-58 MHz
Consider the following statements:
Statement (I): In AM systems the modulation index (0 < m < I) should be high.
Statement (II): The higher the value of m, the greater the power in the sidebands.
Choose the correct option.
A) Both Statement (I) and Statement (II) are individually true and Statement (II) is the correct explanation of Statement (I).
B) Both Statement (I) and Statement (II) are individually true but Statement (II) is not the correct explanation of Statement (I).
C) Statement (I) is true but Statement (II) is false.
D) Statement (I) is false but Statement (II) is true.
Correct answer
A) Both Statement (I) and Statement (II) are individually true and Statement (II) is the correct explanation of Statement (I).
The correct sequence of subsystems in an FM receiver is:
A) Mixer RF amplifier limiter → IF amplifier → discriminator → audio amplifier
B) RF amplifier → mixer limiter → discriminator → IF amplifier → audio amplifier
C) RF amplifier mixer → IF amplifier → limiter→discriminator audio amplifier
D) Mixer → IF amplifier → limiter→ audio amplifier → discriminator
Correct answer
A) Mixer RF amplifier limiter → IF amplifier → discriminator → audio amplifier
Which of the following is NOT a method for generating FM?
By reactance modulator
By varactor diode
By switching modulator
By Armstrong modulator
Correct answer
By reactance modulator
The ionosphere acts as the reflecting surface for the waves in which of the following modes of propagation?
Ground wave
Space wave
Sky wave
LOS
Correct answer
Ground wave
RF carrier 15 kV at 1 MHz is amplitude modulated and modulation index is 0.8. Find the peak voltage of the signal.
18 kV
12 kV
18.75 kV
22 kV
Correct answer
18 kV
One of the main functions of the RF amplifier in a superheterodyne receiver is to:
Permit better adjacent channel rejection
Provide improved tracking
Increase the tuning range of the receiver
Improve the rejection of the image frequency
Correct answer
Permit better adjacent channel rejection
Which of the following statements about the matched filter in a communication receiver are correct?
I. It produces ISI.
II. It maximizes the SNR at the detection instant.
Its impulse response depends on the signal shape.
IV. It may produce signal dispersion.
Select the correct answer from the codes given below:
II and III only
III and IV only
I, II and IV only
II, III and IV only
Correct answer
II and III only
Match List-X (Modulation/Reception Techniques) with List-Y (Disadvantages) and select the correct answer using the codes given below the lists:
| List-X | List-Y |
|---|---|
| i. Superheterodyne | 1. Threshold effect |
| ii. FM | 2. Granular noise |
| iii. PCM | 3. Image frequency interference |
| iv. Delta modulation | 4. Quantization noise |
Codes:
i ii iii iv
1, 3, 4, 2
3, 1, 4, 2
1, 3, 2, 4
3, 1, 2, 4
Correct answer
1, 3, 4, 2
Match List-X (Frequencies) with List-Y (Range) and select the correct answer using the codes given below the lists:
| List-X | List-Y |
|---|---|
| i. Audio Frequency (AF) | 1. 3 kHz to 300 GHz |
| ii. Intermediate Frequency (IF) | 2. 20 Hz to 20 kHz |
| iii. Radio Frequency (RF) | 3. 10 MHz to 108 MHz |
Codes:
i ii iii
2, 1, 3
3, 1, 2
2, 3, 1
3, 2, 1
Correct answer
2, 1, 3