➤ Hello In this page provides you Question/MCQ In this question Based on the Modulation ,Demodulation, pulse code modulation shift keying and ASK,FSK,PSK etc.
Q.1 What is demodulation in communication systems?
Detection
Recovering information from the modulating signal
Both A & B
None
Explanation
Demodulation, often called detection, is the process of extracting the original information-bearing signal from a modulated carrier wave.
Q.2 Which of the following parameters remains constant in Amplitude Modulation (AM)?
Amplitude
Frequency
Phase
Both B & C
Explanation
In Amplitude Modulation, only the amplitude of the carrier wave is varied; the frequency and phase are kept constant.
Q.3 Which of the following are recognized AM demodulation techniques?
Square law Demodulator
Envelope Detector
Phase Discriminator
Both A & B
Explanation
Square law demodulators and envelope detectors are common circuits used to recover the message signal from an AM wave.
Q.4 The process of recovering the original information signal from the received carrier is specifically known as?
Modulation
De-Modulation
Detection
None
Explanation
Detection is the specific term for the process used by a receiver to extract the baseband signal from the modulated carrier.
Q.5 What is the full form of FM in the context of signal modulation?
Frequency Module
Fresh Modulation
Frequency Modulation
None
Explanation
FM stands for Frequency Modulation, where the frequency of the carrier wave is varied according to the amplitude of the input signal.
Q.6 Signal transmission where no power is consumed by the carrier itself is known as?
Amplitude Modulation
Frequency Modulation
Sideband suppressed carrier signal
None
Explanation
Suppressed carrier systems (like DSB-SC) are more power-efficient because the carrier, which contains no information, is removed before transmission.
Q.7 Why is modulation required in wireless communication?
Reducing noise during transmission
Reduction of antenna height
Multiplexing multiple signals
All of the above
Explanation
Modulation allows for smaller antennas, enables multiple signals to share a medium, and improves resistance to noise and interference.
Q.8 What are the primary advantages of using an RF amplifier in a receiver?
Better Sensitivity
Improved signal-to-noise ratio
Better selectivity
All of the above
Explanation
RF amplifiers boost weak signals (sensitivity), help filter unwanted frequencies (selectivity), and reduce the relative impact of noise.
Q.9 In many networking contexts (like modems), modulation is the activity used to convert?
Analog to Digital
Digital to Analog
Digital to Binary
None
Explanation
A modem (Modulator-Demodulator) uses modulation to convert digital computer data into analog signals for transmission over phone lines.
Q.10 In many networking contexts, demodulation is the activity used to convert?
Analog to Digital
Digital to Analog
Digital to Binary
None
Explanation
Demodulation in a modem converts the received analog signals back into digital data that a computer can understand.
Q.11 Which of the following are examples of low-level modulation circuits?
Square law diode modulation
Switching modulation
Packet modulation
Both A & B
Explanation
Square law and switching modulators are types of low-level modulation where the process occurs at low power levels.
Q.12 Which of the following is true regarding the phase shift method of SSB generation?
Includes two balanced modulators
Uses two phase shifting networks
Avoids the use of bulky filters
All of these
Explanation
The phase shift method uses cancellation properties of out-of-phase signals to generate SSB, eliminating the need for sharp-cutoff filters.
Q.13 Which of the following occurs during the synchronous detection of an AM signal?
A carrier is locally generated
The signal is passed through a low pass filter
The original signal is accurately recovered
All of these
Explanation
Synchronous detection requires a local carrier identical in frequency and phase to the original carrier to demodulate the signal.
Q.14 What is the full form of PM in modulation technology?
Phase Modulation
Passed Modulation
Phase Module
None
Explanation
PM stands for Phase Modulation, where the phase of the carrier wave is varied in accordance with the message signal.
Q.15 A Ring Modulator is characterized by which of the following?
Used for DSB-SC generation
Consists of four diodes in a ring
Acts as a product modulator
All of these
Explanation
A ring modulator is a type of switching modulator that uses four diodes to produce a Double Sideband Suppressed Carrier (DSB-SC) signal.
Q.16 Which of these are standard AM demodulation techniques?
Square law demodulator
Envelope detector
PLL Detector
Both A & B
Explanation
While PLLs are used for FM, AM typically relies on envelope detectors for simplicity or square law demodulators.
Q.17 What are the characteristics of square law modulators?
Non-linear current-voltage characteristics
Used for Amplitude Modulation
Used for Frequency Modulation
Both A & B
Explanation
Square law modulators utilize the non-linear region of a diode or transistor to produce the sum and difference frequencies needed for AM.
Q.18 Which type of amplifier is typically used for low-level modulation?
Class A
Class C
Class B
None
Explanation
Class A amplifiers are linear and used in low-level modulation to maintain signal fidelity before the power amplification stage.
Q.19 What does the acronym QAM stand for in networking and modulation?
Quadrature Amplitude Modulation
Quadrature Amplitude Module
Quadrature Applied Modulation
None
Explanation
QAM (Quadrature Amplitude Modulation) transmits two message signals by modulating the amplitudes of two carrier waves that are out of phase by 90 degrees.
Q.20 What does the acronym AGC stand for in communication receivers?
Automatic Gain Control
Automation Gain Control
Automatic gain Control
None
Explanation
AGC (Automatic Gain Control) is a circuit that automatically adjusts the gain of an amplifier to maintain a constant output level despite varying input strengths.