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:
Continue Practice Exam Test Questions Part XIII of the Series
601. It is the first stage of the receiver and is therefore often called the receiver front end.
- a. mixer
- b. RF section
- c. local oscillator
- d. IF stage
602. One of the following cannot be used to remove the unwanted sideband in SSB. This is the
- a. filter system
- b. phase-shift method
- c. third method
- d. balanced modulator
603. R3E modulation is sometimes used to
- a. allow the receiver to have a frequency synthesizer
- b. simplify the frequency stability problem in reception
- c. reduce the power that must be transmitted
- d. reduce the bandwidth required for transmission
604. To provide two or more voice circuits with the same carrier, it is necessary to use
- a. ISB
- b. carrier reinsertion
- c. SSB with pilot carrier
- d. Lincomplex
605. A type of AGC is similar to conventional AGC except that the receive signal is monitored closer to the front end of the receiver and the correction voltage is fed forward to the IF amplifiers
- a. ISB
- b. delayed AGC
- c. complex AGC
- d. simple AGC
606. Having an information signal change some characteristics of a carrier signal is called
- a. multiplexing
- b. modulation
- c. duplexing
- d. linear mixing
607. A circuit that compensates for minor variations in the received RF signal level
- a. automatic volume control
- b. automatic frequency control
- c. automatic gain control
- d. automatic phase control
608. Which of the following is not true about AM?
- a. the carrier amplitude varies
- b. the carrier frequency remains constant
- c. the carrier frequency changes
- d. the information signal amplitude changes the carrier amplitude
609. A modulator circuit performs what mathematical operation on its two inputs?
- a. addition
- b. multiplication
- c. division
- d. square root
610. If m is greater than 1, what happens?
- a. normal operation
- b. carrier drops to 0
- c. information signal is distorted
- d. nothing happens
611. The outline of the peaks of a carrier has the shape of modulating signal and is called _______.
- a. trace
- b. wave shape
- c. envelope
- d. carrier variation
612. Overmodulation occurs when
- a. Vm > Vc
- b. Vm < Vc
- c. Vm = Vc
- d. Vm = Vc = 0
613. The new signal produced by modulation are called __________.
- a. spurious emission
- b. harmonics
- c. intermodulation products
- d. sidebands
614. An AM signal has a carrier power of 5W, the percentage of modulation is 80 percent. The total power sideband is _________.
- a. 0.8 W
- b. 1.6 W
- c. 2.5 W
- d. 4.0 W
615. For 100 percent modulation, what percentage of power is in each sideband
- a. 25 percent
- b. 33.3 percent
- c. 50 percent
- ` d. 100 percent
616. An AM transmitter has a percentage of modulation of 88, the carrier power is 440 W. The power in one sideband is
- a. 85 W
- b. 110 W
- c. 170 W
- d. 610 W
617. An AM signal without the carrier is called ______.
- a. SSB
- b. vestigial sidebands
- c. FM signal
- d. DSB
618. It is a form of amplitude modulation in which the carrier is transmitted at full power, but only one of the sidebands is transmitted.
- a. SSBFC
- b. SSBSC
- c. SSBRC
- d. ISB
619. With single-sideband full carrier, 100% modulation would mean a carrier power of how many percent of the total transmitted power?
- a. 80%
- b. 20%
- c. 50%
- d. 40%
620. It is a form of amplitude modulation in which the carrier is suppressed and one of the sidebands removed
- a. SSBFC
- b. ISB
- c. vestigial sideband
- d. SSBSC
621. It is a form of amplitude modulation in which one sideband is totally removed and the carrier voltage is reduced to approximately 10% of its unmodulated amplitude
- a. independent sideband
- b. SSBFC
- c. SSBRC
- d. SSBSC
622. It is a form of amplitude modulation in which a single carrier frequency is independently modulated by two different modulating signal.
- a. vestigial sideband
- b. DSBFC
- c. independent sideband
- d. SSBFC
623. It is a form of amplitude modulation in which the carrier and one complete sideband are transmitted, but only part of the second sideband is transmitted.
- a. independent sideband
- b. vestigial sideband
- c. DSBFC
- d. SSBSC
624. It is the rms power developed at the crest of the modulation envelope of SSBSC.
- a. carrier power
- b. total transmitted power
- c. sideband power
- d. peak envelope power
625. Which of the following is not true about single-sideband transmission?
- a. power is conserved
- b. selective fading is eliminated
- c. bandwidth is conserved
- d. tuning is easy
626.A circuit that produces a double sideband suppressed carrier signal is called ____________.
- a. filter
- b. mixer
- c. demodulator
- d. balanced modulator
627. A balanced modulator is sometimes called _________.
- a. balanced ring modulator
- b. balanced resistor modulator
- c. balanced lattice modulator
- d. any of these
628. A type of filter that receives electrical energy, converts it to mechanical vibrations and then converts the vibrations back to electrical energy at its output.
- a. crystal filter
- b. mechanical filter
- c. LC filter
- d. SAW filter
629. A type of filter that uses acoustic energy rather than electromechanical energy to provide excellent performance for precise bandpass filtering.
- a. SAW filter
- b. RC filter
- c. mechanical filter
- d. crystal filter
630. The difference between the IF and the BFO frequencies is called _________.
- a. information signal
- b. beat frequency
- c. carrier signal
- d. heterodyned signal
631. It is a circuit which is a narrowband PLL that tracks the pilot carrier in the composite SSBRC receiver signal and uses the recovered carrier to regenerate coherent local oscillator frequencies in the synthesizer.
- a. beat frequency oscillator
- b. mechanical filter
- c. local oscillator
- d. carrier recovery circuit
632. A system that provides narrowband voice communications for land mobile services with nearly the quality achieved with FM systems and do it using less than one-third the bandwidth.
- a. SSBSC
- b. DSBFC
- c. ACSSB
- d. SSBAC
633. It is a process of combining transmissions from more than one source and transmitting them over a common facility such as metallic or optical fiber cable or a radio-frequency channel.
- a. buffering
- b. modulation
- c. multiplexing
- d. demultiplexing
634. It is an analog method of combining two or more analog sources that originally occupied the same frequency band in such a manner that the channels do not interfere with each other.
- a. ATM
- b. FDM
- c. TDM
- d. WDM
635. It is a multiplexing method that uses double-sideband suppressed-carrier transmission to combine two information sources into a single composite waveform.
- a. QM
- b. WDM
- c. TDM
- d. FDM
636. Single-sideband transmitters are rated in _________.
- a. rms power
- b. dc power
- c. average power
- d. peak envelope power
637. In an SSB transmitter, one is most likely to find a __________.
- a. class C audio amplifier
- b. tuned modulator
- c. class B RF amplifier
- d. class A RF output amplifier
638. Indicate in which one of the following only one sideband is transmitted:
- a. H3E
- b. A3E
- c. B8E
- d. C3F
639. One of the following cannot be used to remove the unwanted sideband in SSB. This is the
- a. filter system
- b. phase-shift method
- c. third method
- d. balanced modulator
640. R3E modulation is sometimes used to
- a. allow the receiver to have a frequency synthesizer
- b. simplify the frequency stability problem in reception
- c. reduce the power that must be transmitted
- d. reduce the bandwidth required for transmission
641. To provide two or more voice circuits with the same carrier, it is necessary to use
- a. ISB
- b. carrier reinsertion
- c. SSB with pilot carrier
- d. Lincomplex
642. The main advantage of SSB over standard AM or DSB is
- a. less spectrum is used
- b. simpler equipment is used
- c. less power is consumed
- d. a higher modulation percentage
643. In SSB, which sideband is the best to use?
- a. upper
- b. lower
- c. neither
- d. depends upon the use
644. The output of an SSB transmitter with a 3.85 MHz carrier and a 1.5 kHz sine wave modulating tone is
- a. a 3.8485 MHz sine wave
- b. a 3.85 MHz sine wave
- c. 3.85, 3.8485 and 3.8515 MHz sine waves
- d. 3848.5 and 3851.5 MHz sine waves
645. An SSB transmitter produces a 400 V peak to peak signal across a 52 ohm antenna load. The PEP output is
- a. 192.2 W
- b. 384.5 W
- c. 769.2 W
- d. 3077 W
646. The output power of SSB transmitter is usually expressed is terms of
- a. average power
- b. RMS power
- c. peak to peak power
- d. peak envelope power
647. An SSB transmitter has a PEP rating of 1 kilowatts. The average output power is in the range of
- a. 150 to 450 W
- b. 100 to 300 W
- c. 250 to 333 W
- d. 3 to 4 kW
648. In amplitude modulation technique, the unmodulated carrier is referred to as having___..
- a. 100% modulation
- b. 0% modulation
- c. 50% modulation
- d. overmodulated
649. What is the process in radio communication where the information or intelligent signal is at lower frequency is put unto higher radio frequency for transmission to receiving station?
- a. detection
- b. mixing
- c. modulation
- d. demodulation
650. Which of the following signals is suppressed by balanced modulator circuit?
- a. 1st IF signal
- b. carrier signal
- c. harmonics
- d. 2nd IF signal
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