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 III of the Series
101. It is the width of frequencies within the spectrum occupied by a signal and used by the signal for conveying information.
- A. Band
- B. Bandwidth
- C. Electronic spectrum
- D. Frequency band
102. Which transmit only one sideband?
- A. H3E
- B. C3F
- C. A3E
- D. B8E
103. ______ is kind of modulation in which the modulated wave is always present.
- A. Carrier modulation
- B. Continuous modulation
- C. Log-periodic modulation
- D. Square-wave modulation
104. A type of modulation in which no signal is present between pulses.
- A. Pulse modulation
- B. FSK
- C. QAM
- D. PAM
105. What describes the amount of amplitude change present in an AM waveform?
- A. Percent modulation
- B. Modulation constant
- C. Envelope of modulation
- D. Coefficient of modulation
106. _______ is a form of amplitude distortion introduced when the positive and negative alternations in the AM modulated signals are not equal.
- A. Envelope distortion
- B. Spurious emission
- C. Carrier shift
- D. Johnson noise
107. What is the advantage of phase modulation over direct FM frequency modulation?
- A. Multipliers can be used
- B. The deviation is smaller
- C. Simplicity and practicality
- D. The oscillator is crystal-controlled
108. If the spectrum is shifted in frequency with no other changes, this is known as
- A. Frequency multiplication
- B. Sideband movement
- C. Baseband reorientation
- D. Frequency translation
109. A device which is capable of causing frequency translation
- A. High-Q tank circuit
- B. Balanced modulator
- C. Low-Q tank circuit
- D. IF strip
110. If the frequency of each component in a signal spectrum is increased by the same fixed amount, this known as
- A. Modulation
- B. Frequency translation
- C. Up conversion
- D. Both B and C
111. A particular amplifier is designed to be a frequency doubler. If the input signal frequency is 15.4 MHz, a circuit in the output will be tuned to
- A. 7.7 MHz
- B. 15.4 MHz
- C. 30.8 MHz
- D. 61.6 MHz
112. A sine wave of 293 MHz is phase-modulated to achieve a maximum phase deviation of 0.2 radian. After passing through a frequency tripler, the maximum phase deviation will be
- A. 0.2 radian
- B. 0.3 radian
- C. 0.4 radian
- D. 0.6 radian
113. Any device to be used as a frequency multiplier must be
- A. Active
- B. Passive
- C. Linear
- D. Nonlinear
114. A particular amplifier circuit used for frequency doubling.
- A. Push-push
- B. Push-pull
- C. Pull-push
- D. Pull-pull
115. Frequency division is useful in the implementation of a
- A. AM demodulator
- B. Frequency synthesizer
- C. AGC circuit
- D. FM demodulator
116. Frequency division by 12 will require how many flip-flops in the counter?
- A. 3
- B. 4
- C. 6
- D. 12
117. Identify an electronic device, not specifically designed for the purpose, which can be used as a phase detector.
- A. Wien bridge
- B. Colpitts oscillator
- C. Balanced modulator
- D. Butterworth filter
118. A particular frequency synthesizer contains only a single crystal. What words describe this synthesizer?
- A. Crystal modulated
- B. Inexact
- C. Indirect
- D. Deficient
119. A recognizable feature of a CW transmitter is
- A. Keyed transmitter
- B. Power amplification
- C. Frequency generation
- D. All of these
120. The term “pulling” refers to
- A. The change of the crystal oscillator frequency by loading
- B. One half-cycle operation of a push-pull amplifier
- C. Loading on the transmitter caused by the antenna connection
- D. Reduction of the power supply terminal voltage as the transmitter is keyed.
121. When frequency modulation is achieved by initial phase modulation, this is called
- A. Angular modulation
- B. Direct FM
- C. Indirect FM
- D. Indirect synthesis
122. A disadvantage of direct FM is the need for
- A. AGC
- B. AFC
- C. A frequency synthesizer
- D. Phase modulation
123. Direct FM can be achieved by
- A. A reactance tube modulator
- B. A varactor diode
- C. And AGC circuit
- D. Both A and B
124. A receiver in which all RF amplifier stages require manual tuning to the desired RF is called
- A. Superheterodyne
- B. Autodyne
- C. TRF
- D. AFC
125. Why is it often necessary to precede the demodulator by amplifier stages in a receiver?
- A. To improve fidelity
- B. To reduce receiver noise
- C. To eliminate image response
- D. Weak antenna signals
126. A serious disadvantage of the TRF receiver.
- A. Bandwidth variations over the tuning range
- B. The weight and cost
- C. The requirements for a closely regulated power supply
- D. The requirements for a half-wave antenna
127. Identify which is not a part of a superheterodyne receiver.
- A. Local oscillator
- B. Modulator
- C. IF amplifier
- D. Demodulator
128. Which major element will not be found in every superheterodyne receiver?
- A. R–F amplifier
- B. Mixer
- C. Local oscillator
- D. IF amplifier
129. Which major element of a superheterodyne receiver must be nonlinear?
- A. R-F amplifier
- B. Mixer
- C. Local oscillator
- D. IF amplifier
130. The change of the modulated carrier frequency from the original RF to the IF of the superheterodyne receiver is known as
- A. Frequency multiplication
- B. Frequency allocation
- C. Frequency substitution
- D. Frequency translation
131. The key to achieving receiver sensitivity is the reduction of
- A. Image response
- B. Mixer harmonic products
- C. Spurious frequency response
- D. Internal noise
132. Which of the following receiver design objectives is not impossible?
- A. Elimination of galactic noise
- B. Elimination of atmospheric noise
- C. Elimination of man-made noise
- D. Reduction of receiver internal noise
133. In comparing the S/N ratio for the input to the receiver with the S/N ratio for the output, the latter is
- A. Smaller
- B. The same
- C. Greater
- D. Infinite
134. The characteristic of a receiver that specifies the self-generated noise.
- A. Noise immunity
- B. Noise factor
- C. Noise figure
- D. Noise margin
135. An FM receiver with an I-F of 10.7 MHz is tuned to 98.7 MHz. What is the numerical value of the image frequency?
- A. 77.3 MHz
- B. 88.0 MHz
- C. 109.4 MHz
- D. 120.1 MHz
136. A source of RF interference exists at 109.9 MHz. For which frequency in the FM broadcast band will this be the image frequency?
- A. 21.4 MHz
- B. 88.5 MHz
- C. 99.2 MHz
- D. 110.7 MHz
137. The ratio of the superheterodyne receiver response at the desired carrier frequency to that at the image frequency is called
- A. The sensitivity
- B. The selectivity
- C. The image frequency
- D. The image rejection ratio
138. The core of an IF transformer usually contains
- A. Teflon
- B. Computer nylon
- C. Powdered iron
- D. Laminated steel
139. Shape factor is a measure of
- A. Bandwidth
- B. Skirt steepness
- C. Coupling coefficient
- D. Critical coupling
140. _______ is the function which tends to maintain the sound volume level of a voice receiver nearly constant for a large signal strength range.
- A. Squelch
- B. Muting
- C. AGC
- D. AFC
141. The function which tends to silence the receiver in the absence of transmitted carrier.
- A. Squelch
- B. Muting
- C. AGC
- D. AFC
142. What device is incorporated in a communications receiver to reduce impulse noise?
- A. Front-end processor
- B. Squelch circuit
- C. AGC
- D. Noise blanker
143. What type of signal in which a receiver selectivity of 2.4 kHz in the I-F circuitry is optimum?
- A. FM voice
- B. Double-sideband AM voice
- C. FSK data
- D. SBB voice
144. If the input to a detector stage is an amplitude-modulated (A3E) IF signal then the output from the stage is
- A. A lower frequency carrier
- B. The audio voice information
- C. A Morse-code signal
- D. The upper or lower set of sidebands
145. In a capacitive type, reactance-tube modulator connected across an oscillator tuned circuit, a more negative voltage on the grid of the reactance tube will cause
- A. An increase of the oscillator frequency
- B. An decrease of oscillator frequency
- C. An increase of the reactance-tube capacitance
- D. An increase of the reactance tube ac plate current
146. The limiting condition for sensitivity in a communications receiver is
- A. The noise floor of the receiver
- B. Power supply output ripple
- C. The two-tone intermodulation distortion
- D. The input impedance to the detector
147. When a communications receiver is tuned to a strong signal, the AGC bias is measured and found to be zero. The fault cannot be caused by a/an
- A. Defective IF stage
- B. Defective local oscillator
- C. Defective RF stage
- D. Open circuit in the AGC’s filter capacitor
148. The term used to refer to the condition where the signals from a very strong station are superimposed on other signals being received
- A. Cross-modulation interference
- B. Intermodulation interference
- C. Receiver quieting
- D. Capture effect
149. The limiter stage of an FM receiver
- A. Behaves as a low-pass filter
- B. Limits the amplitude of the IF signal to the required level
- C. Behaves as a high-pass filter
- D. Behaves as a bandstop filter
150. Motorboating (low-frequency oscillations) in an amplifier can be stopped by
- A. Grounding the screen grid
- B. Connecting a capacitor between the B+ and lead ground
- C. By passing the screen grid resistor with a 0.1 µF capacitor
- D. Grounding the plate
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