MCQs in Modulation Part XII

(Last Updated On: December 8, 2017)

MCQs in Modulation - Part XII

This is the Multiples Choice Questions Part 12 of the Series in Modulation as one of the Communications Engineering topic. In Preparation for the ECE Board Exam make sure to expose yourself and familiarize in each and every questions compiled here taken from various sources including but not limited to past Board Examination Questions in Electronic System and Technologies, Communications Books, Journals and other Communications References.

Online Questions and Answers Topic Outline

  • MCQs in Amplitude Modulation
  • MCQs in Phase Modulation
  • MCQs in Sound Pressure Level
  • MCQs in Frequency Modulation
  • MCQs in Pulse Modulation

MCQs in Modulation Series

Following is the list of multiple choice questions in this brand new series:

Modulation MCQs
PART 1: MCQs from Number 1 – 50                        Answer key: PART I
PART 2: MCQs from Number 51 – 100                   Answer key: PART II
PART 3: MCQs from Number 101 – 150                 Answer key: PART III
PART 4: MCQs from Number 151 – 200                 Answer key: PART IV
PART 5: MCQs from Number 201 – 250                 Answer key: PART V
PART 6: MCQs from Number 251 – 300                 Answer key: PART VI
PART 7: MCQs from Number 301 – 350                 Answer key: PART VII
PART 8: MCQs from Number 351 – 400                 Answer key: PART VIII
PART 9: MCQs from Number 401 – 450                 Answer key: PART IX
PART 12: MCQs from Number 551 – 600                 Answer key: PART XII

Continue Practice Exam Test Questions Part XII of the Series

551. In the phasing method of SSB generation, one sideband is cancelled due out to

  • a. phase shift
  • b. sharp selectivity
  • c. carrier suppression
  • d. phase inversion

552. It is caused by poor front-end selectivity or inadequate image frequency rejection.

  • a. optimal coupling
  • b. double spotting
  • c. spurious pointing
  • d. under coupling

553. It is a high-gain, low noise, tuned amplifier that, when used is the first active encountered by the receiver signal.

  • a. mixer
  • b. local oscillator
  • c. RF amplifier
  • d. detector

554. It is a high performance microwave receiver at the input stage. In the RF section of optimize their noise figure.

  • a. high-power amplifier
  • b. low noise amplifier
  • c. buffer amplifier
  • d. local oscillator

555. A balanced modulator used to demodulates a SSB signal is called

  • a. transponder
  • b. product detector
  • c. converter
  • d. modulator

556. Which of the following is not the other name of a balanced modulator?

  • a. balanced mixer
  • b. product detector
  • c. product modulator
  • d. none of these

557. ________ amplifiers are relatively high gain tuned amplifiers that are very similar to RF amplifiers, except that it operates over a relatively narrow, fixed frequency band.

  • a. IF amplifiers
  • b. low-noise amplifiers
  • c. buffer amplifiers
  • d. high-power amplifier

558. Type of tuned circuit where both the primary and secondary sides of the transformer are tuned tank circuits

  • a. RLC tuned circuit
  • b. double-tuned circuit
  • c. single-tuned circuit
  • d. LC tuned circuit

559. Frequency translation is done with a circuit called _______.

  • a. summer
  • b. multiplier
  • c. filter
  • d. mixer

560. Low noise RF amplifiers use what type biasing?

  • a. class A
  • b. class B
  • c. class AB
  • d. class C

561. Its purpose is to down-convert the incoming radio frequencies to intermediated frequencies.

  • a. local oscillator
  • b. RF amplifier
  • c. detector
  • d. mixer

562. It is a non-linear amplifier similar to modulator, except that the output is turned to different between the RF and local oscillator frequencies.

  • a. RF amplifier
  • b. local oscillator
  • c. mixer
  • d. detector

563. Mixing for frequency conversion is the same as

  • a. rectification
  • b. AM
  • c. linear summing
  • d. filtering

564. The most common technique used for coupling IF amplifiers

  • a. resistive coupling
  • b. inductive coupling
  • c. capacitive coupling
  • d. direct coupling

565. When the modulation index of an AM wave doubled, the antenna current is also doubled. The AM system being used is

  • a. single-sideband, full carrier (H3E)
  • b. vestigial sideband (C3F)
  • c. single sideband, suppressed carrier (J3E)
  • d. double sideband, full carrier (A3E)

566. The ability of a coil to induce a voltage within its own windings is called

  • a. mutual inductance
  • b. coefficient coupling
  • c. self- inductance
  • d. inductance

567. If the carrier of a 100 percent modulated AM wave is suppressed the percentage power saving will be

  • a. 50
  • b. 150
  • c. 100
  • d. 66.66

568. The ability of one coil to induce a voltage in another coil is called _________.

  • a. coefficient coupling
  • b. mutual inductance
  • c. inductance
  • d. self-inductance

569. Which of the following cam be used as a mixer?

  • a. balanced modulator
  • b. FET
  • c. diode modulator
  • d. all of the above

570. It is the ratio of the secondary flux to primary flux

  • a. Q factor
  • b. coefficient coupling
  • c. self-inductance
  • d. coefficient of modulation

571. Type of coupling where the secondary voltage is relatively low and the bandwidth is narrow.

  • a. tight coupling
  • b. optimum coupling
  • c. loose coupling
  • d. critical coupling

572. An AM signal, transmitted information is contained within the

  • a. carrier
  • b. modulating signal
  • c. sidebands
  • d. envelope

573. Type of coupling which has high gain and a broad bandwidth

  • a. optimum coupling
  • b. tight coupling
  • c. double coupling
  • d. loose coupling

574. It is the point where the reflected resistance is equal to primary resistance and the Q of the primary tank circuit is halved and the bandwidth doubled.

  • a. critical coupling
  • b. tight coupling
  • c. loose coupling
  • d. optimum coupling

575. The desired output from a mixer is usually selected with a

  • a. phase-shift circuit
  • b. crystal filter
  • c. resonant circuit
  • d. transformer

576. It is caused by the reactive element of the reflected impedance being significant enough to change the resonant frequency of the primary tuned circuit.

  • a. optimum coupling
  • b. critical coupling
  • c. double peaking
  • d. flux linkage

577. IF transformers come as specially designed tuned circuits in groundable metal packages called _______.

  • a. IF cans
  • b. IF container
  • c. IF strip
  • d. IF tetrapack

578. The AM detector is sometimes called _______.

  • a. first detector
  • b. third detector
  • c. second detector
  • d. fourth detector

579. The mixer is sometimes called _________.

  • a. first detector
  • b. third detector
  • c. second detector
  • d. fourth detector

580. The two inputs to a mixer are the signal to be translated and a signal from

  • a. modulator
  • b. filter
  • c. antenna
  • d. local oscillator

581. AM demodulator is commonly called _________.

  • a. phase detector
  • b. peak detector
  • c. frequency detector
  • d. transistor detector

582. A type of detector that detects the shape of the input envelope

  • a. peak detector
  • b. phase detector
  • c. diode detector
  • d. shape detector

583. The ratio of the peak modulating signal voltage to the peak carrier voltage is referred to as

  • a. voltage ratio
  • b. decibels
  • c. modulation index
  • d. mix factor

584. A circuit that automatically increases the receiver gain for weak RF input levels and automatically decreases the receiver gain when a strong RF signal is received.

  • a. automatic volume control
  • b. automatic frequency control
  • c. automatic gain control
  • d. automatic phase control

585. Which is not a type of AGC?

  • a. simple AGC
  • b. forward AGC
  • c. delayed AGC
  • d. complex AGC

586. The value Vmax and Vmin as read from AM wave on an oscilloscope are 3.0 and 2.8. The percentage of modulation is

  • a. 10 percent
  • b. 41.4 percent
  • c. 80.6 percent
  • d. 93.3 percent

587. Amplitude modulation is used for broadcasting because

  • a. it is more noise immune than other modulation systems
  • b. compared to other systems it requires less transmitting power
  • c. its use avoids receiver complexity
  • d. no other modulation system can provide the necessary bandwidth for high fidelity

588. Type of AGC that prevents the AGC feedback voltage from reaching the RF or IF amplifiers until the RF level exceeds a predetermined magnitude.

  • a. forward AGC
  • b. delayed AGC
  • c. complex AGC
  • d. simple AGC

589. A circuit with a purpose to quiet a receiver in the absence of a received signal.

  • a. automatic gain control
  • b. automatic frequency control
  • c. squelch circuit
  • d. automatic volume control

590. A section of a audio stage of a receiver that removes sporadic, high amplitude noise transients of short duration, such as impulse noise.

  • a. squelch circuit
  • b. clampers
  • c. clippers
  • d. peak detector

591. A circuit that detects the occurrence of a high-amplitude, short duration noise spike then mutes the receiver by shutting off a portion of the receiver of the duration of the pulse.

  • a. squelch circuit
  • b. limiter
  • c. clamper
  • d. blanking circuit

592. The opposite modulation is

  • a. reverse modulation
  • b. downward modulation
  • c. unmodulation
  • d. demodulation

593. For good image-frequency rejection, what is the desired value of the intermediate frequency?

  • a. relatively low IF
  • b. very low IF
  • c. relatively high IF
  • d. very high IF

594. With high-gain selective amplifiers that are stable and easily neutralized. what is the desired value of intermediate frequency?

  • a. low IF
  • b. medium IF
  • c. high IF
  • d. very high IF

595. It is defined as the ratio of the demodulated signal level at the output receiver to the RF signal level at the input to the receiver.

  • a. received signal level
  • b. figure of merit
  • c. effective radiated power
  • d. net receiver gain

596. It is the process of modifying the characteristic of one signal in accordance with some characteristic of another signal.

  • a. multiplexing
  • b. mixing
  • c. modulation
  • d. summing

597. The imaginary line on the carrier waveform of the amplitude modulated signal is called __________.

  • a. sidebands
  • b. envelope
  • c. spurious emission
  • d. information

598. Indicate the false statement regarding the advantages of the phase cancellation method of obtaining SSB over the filter method is false:

  • a. more channel space available
  • b. transmitter circuits must be stable, giving better spectrum
  • c. the signal is more noise resistant
  • d. much less power is required for the same signal strength

599. Indicate which one of the following advantages of the phase cancellation method of obtaining SSB over the filter method is false:

  • a. switching from one sideband to the other simpler
  • b. it is possible to generated SSB at any frequency
  • c. SSB with lower audio frequencies present can be generated.
  • d. There are more balanced modulators, therefore the carrier is suppressed better

600. The most commonly used filters is SSB generation are

  • a. mechanical
  • b. RC
  • c. LC
  • d. low-pass

Complete List of MCQs in Communications Engineering per topic

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