1. ______ is the maximum sideband suppression value using filter system.
A. 50 dB B. 60 dB C. 40 dB D. 30 dB
2. _______ determines the number of sideband components in FM.
A. carrier frequency B. modulation frequency C. modulation index D. deviation ratio
3. One of the following transmits only one sideband. A. H3E
B. R3E C. A3E D. B8E
4. What produces the sidebands on FM? A. signal amplitude
B. carrier harmonics C. baseband frequency D. broadband frequency
5. Which test instrument displays the carrier and the sidebands amplitude with frequency to frequency?
A. oscilloscope B. spectrum analyzer C. frequency analyzer D. amplitude analyzer
6. Mixer is also known as a ________. A. modulator
B. suppressor C. converter D. beater
7. Which one of the following emission transmits the lower sideband and half of the upper sideband?
A. A5C B. J3E C. A3J D. A3H
8. An FM receives signal ______. A. vary in amplitude with modulation B. vary in frequency with modulation
C. vary in frequency and amplitude with wideband modulation
D. is not immune to noise
9. The process of impressing intelligence on the carrier is called
A. modulation B. detection C. mixing D. impression
10. ______ is an electronic instrument used to show both the carrier and the sidebands of a modulated signal in the frequency domain.
A. spectrum analyzer B. oscilloscope C. digital counter D. frequency counter
11. What part of the carrier is varied by the intelligence during modulation in an AM system?
A. phase B. frequency C. amplitude D. both a and c
12. The difference between the RF carrier and the modulating signal frequencies is called the
A. USB B. LSB C. Sideband D. Carrier frequency
13. What stage in a radio transmitter isolates the oscillator from the load?
A. Oscillator B. Buffer C. Separator D. Mixer
14. The frequency of the unmodulated carrier in FM system is
A. modulating frequency B. center frequency C. carrier frequency D. deviation frequency
15. The ratio of maximum deviation to the maximum modulating frequency is called
A. carrier swing B. deviation ratio C. modulation factor D. modulation index 16. A carrier signal has A. constant amplitude
B. a frequency of 20 kHz and above C. a varying amplitude
D. the information content
17. The modulated peak value of a signal is 125 V and the unmodulated carrier value is 85 V. What is the modulation index?
A. 0.47 B. 0.68 C. 0.32 D. 1.47
18. An 891 kHz carrier having an amplitude of 80 V is modulated by a 4.5 kHz audio signal having an amplitude of 45 V. The modulation factor is
A. 0.56 B. 0.65 C. 1.78 D. 1.25
19. What is the modulation index of an FM signal having a carrier swing of 75 kHz when the modulating signal has frequency of 3 kHz?
A. 25 B. 12.5 C. 0.04 D. 0.08
20. In a FM system, if modulation index is doubled by having the modulating frequency, what will be the effect on the maximum deviation?
A. No effect
B. Maximum deviation doubles C. Decreases by ½
D. Increases by ¼
21. Which of the following is considered as an indirect method of generating FM?
A. Reactance modulator B. Balanced modulator C. Varactor diode modulator D. Armstrong system
22. To generate an SSB or DSB signal one must use a circuit known as
A. filter modulator B. ring modulator C. balanced modulator D. reactance modulator
23. Which is the first radio receiver? A. TRF receiver
C. Crystal radio receiver D. Heterodyne receiver
24. An interfering signal with a frequency equal to the received signal plus twice the IF is called
A. image frequency B. center frequency C. rest frequency D. interference frequency
25. Double sideband full carrier emission type A. A3J
B. H3E C. R3A D. A3E
26. Single sideband reduced carrier emission type A. H3E
B. R3E C. J3E D. B8E
27. A single sideband suppressed carrier emission type. A. H3E
B. R3E C. J3E D. B8E
28. Independent sideband emission type A. H3E
B. R3E C. J3E D. B8E
29. Vestigial sideband emission type A. C3F
B. J3E C. R3E D. B8E
30. Single sideband full carrier emission type. A. R3E
B. H3E C. J3E D. B8E
31. Phase modulation emission type. A. F3E
B. F3C C. F3F D. G3E
32. Which one is not an advantage of SSB over AM? A. Power saving
B. Requires half the bandwidth C. Wider area of reception D. Better fidelity
33. The advantage of a high level modulated AM transmitter is
A. Less audio power required B. Better fidelity
C. Higher value of operating power D. Less distortion
34. The advantage of a low-level modulated AM transmitter is
A. Less audio power required B. Better fidelity
C. Higher value of operating power D. Less distortion
35. _____ is the bad effect caused by overmodulation in AM transmission.
A. Increase in noise
B. Deviation in the operating frequency C. Interface to other radio services D. Decrease in the output power
36. Which characteristic of a radio receiver refers to its ability to reject an unwanted signal?
A. Sensitivity B. Selectivity C. Fidelity D. Quality
37. What type of emission is frequency modulation? A. F3E
B. G3E C. A3E D. B3E
38. AM transmission power increases with ________. A. Frequency
B. Source C. Load D. Modulation
39. _______ locks the FM receiver to a stronger signal. A. Hall effect
B. Capture effect C. Image frequency D. Homing
40. What is the highest percentage of modulation for AM? A. 50 %
B. 75 %
C. 100 % D. 80 %
41. In FM, the Carson’s Rule states that the bandwidth is equal to twice the sum of the modulating frequency and ______.
A. Carrier signal B. Modulating signal C. Frequency deviation D. Image frequency
42. What is the carrier swing of an FM transmitter when modified by 75%?
A. 53.2 kHz B. 48 kHz C. 56.25 kHz D. 112.5 kHz
43. The modulation system inherently more resistant to noise
A. Single sideband suppressed carrier B. Frequency modulation
C. Pulse-position modulation D. Amplitude shift keying
44. Subcarriers that are arranged so that the channels occupying adjacent frequency bands with some frequency space between them is known as
A. Guard bands B. AM bands C. Band gap D. Void band
45. Modulation of an RF amplifier carrier results in A. Multiple channels
B. Smaller antennas C. Directional propagation D. All of the above
46. A process which occurs in the transmitter A. Mixing
B. Modulation C. Heterodyning D. Demodulation
47. A process which occurs in the receiver A. Beating
B. Modulation C. Mixing D. Demodulation
48. One part of the transmitter that protects the crystal oscillator from “pulling”.
A. Buffer amplifier B. Modulator C. Power amplifier D. Antenna coupler
49. What aspect of the carrier is changed by modulation? A. Frequency
B. Phase C. Amplitude
D. Depends on the type of modulation
50. The amplitude of a sine wave which is modulated by a musical program will
A. Be complex
B. Contain fundamental frequencies C. Contain harmonic frequencies D. All of the above
ANSWER 1. 50 dB 2. modulation index 3. H3E 4. baseband frequency 5. spectrum analyzer 6. converter 7. A3H
8. Vary in frequency with modulation 9. Modulation 10. spectrum analyzer 11. amplitude 12. LSB 13. Buffer 14. Center frequency 15. Deviation ratio
16. a frequency of 20 kHz and above 17. 1.47 18. 0.56 19. 12.5 20. No effect 21. Armstrong system 22. balanced modulator 23. Crystal radio receiver 24. image frequency 25. A3E 26. R3E 27. J3E 28. B8E 29. C3F 30. H3E 31. G3E 32. Better fidelity
33. Higher value of operating power 34. Less audio power required 35. Interface to other radio services 36. Selectivity 37. F3E 38. Modulation 39. Capture effect 40. 100 % 41. Frequency deviation 42. 112.5 kHz 43. Frequency modulation 44. Guard bands 45. All of the above 46. Modulation 47. Demodulation 48. Buffer amplifier
49. Depends on the type of modulation 50. All of the above
51. What will be the result of the gain level being too high for signals entering the modulator?
A. Receiver noise
B. Excessive volume of receiver output C. Oscillator disturbances
D. Distortion and splatter
52. Amplitude modulation causes the amount of transmitter power to
A. Increase B. Decrease C. Remain the same D. Double
53. When a carrier is modulated 100%, the total power increases by what percentage over that of the carrier alone?
A. 25 % B. 50 % C. 75 % D. 100 %
54. When the amplitude of the modulating voltage is increased for AM, the antenna current will
A. Increase B. Decrease C. Remain constant D. Decrease exponentially
55. An increase in transmitter power from 25W to 30W will cause the antenna current to increase from 700mA to A. 800 mA
B. 750 mA C. 767 mA D. 840 mA
56. A second modulating tone having the same amplitude but a different frequency is added to the first at the input to the modulator. The modulation index will be increased by a factor of
A. sq. root of 3 B. sq. root of 2 C. 2
D. 3
57. A 1000 kHz carrier is modulated by a 2500Hz tone. One frequency component of the modulated signal is
A. 1200 Hz B. 5000 Hz C. 1002.5 kHz D. 2500 Hz
58. A 1200 kHz carrier is amplitude-modulated by two tones of 500 Hz and 700 Hz. Which one is a frequency component of the modulated wave?
A. 1195 kHz B. 1199.3 kHz C. 1199.7 kHz D. 1205 kHz
59. Identify a modulation method, or methods in use for a common-emitter configuration
A. Base modulation B. Emitter modulation C. Collector modulation D. Both A and C
60. The RF signal injected into a balanced modulator is 10MHz and the modulating frequency is 1 kHz. Which frequency, or frequencies, will not appear in the output? A. 9.999 MHz
B. 10 MHz C. 10.0001 MHz D. Both A and B
61. Unwanted sidebands in SSB equipment can be suppressed by one or more of the following methods. A. Phasing method
B. Filter method C. Decoder method D. Both A and B
62. Envelope detection is concerned with the process of A. Mixing
B. Heterodyning C. Modulation D. Rectification
63. Diagonal clipping in envelope detection will result in A. Distortion
B. Phase reversal C. Reduced sensitivity
D. Amplitude damage
64. Product detection requires the process of A. Rectification
B. Heterodyning C. Decoding D. Phase shifting
65. A sine wave which is coherent with carrier has identical A. Amplitude
B. Frequency C. Phase angle D. Both B and C
66. Frequency modulation and phase modulation are collectively referred to as
A. Stereo
B. Angle modulation C. High fidelity modulation D. FCC modulation
67. In FM, the change in carrier frequency is proportional to what attribute of the modulating signal?
A. Angle B. Frequency C. Amplitude D. Tone
68. A louder sound, when generating the modulating waveform for FM, will cause a greater
A. Carrier amplitude B. Angle amplitude
C. Distortion at the receiver D. Frequency deviation
69. If a positive change in modulation signal level of 200 mW will cause a positive frequency deviation of 10 kHz, what will be the frequency deviation for a negative change of 10 mV in the level of the modulating signals?
A. 0 B. -5 kHz C. +5 kHz D. +0 kHz
70. A particular 15 kHz modulation tone results in a peak frequency deviation of 75 kHz. What is the modulation index?
A. 5 B. 15 C. 75 D. 3
71. A 15 kHz sine wave frequency modulates an 88 MHz carrier. A sideband frequency will be found at
A. 87.970 MHz B. 87.985 MHz C. 88.015 MHz
D. All of these
72. A device whose capacitance is deliberately made to be a function of the applied voltage
A. Varactor diode B. UJT
C. SAW
D. Variable capacitor
73. A reactance modulator is one method of obtaining A. Indirect FM
B. Direct FM C. Demodulation
D. Low frequency filtering
74. A device, now available in IC form, is useful for direct FM and as one element in the phse-locked loop.
A. AFC B. AGC C. VCO D. LPF
75. _____ is a frequency change process, whereby the phase deviation and frequency deviation are multiplied by some fixed constant.
A. Translation B. Multiplication C. Division D. Addition
76. A circuit that has the function of demodulating the frequency-modulated signal.
A. AFC
B. Envelope detector C. Decoder
D. Foster-Seeley discriminator
77. The ratio detector is superior to the slope detector because
A. It is less sensitive to phase modulation B. It is less sensitive to noise spikes
C. It is less sensitive to interference causing AM D. Both B and C
78. One implementation of a pulse averaging discriminator is
A. A free-running multivibrator B. A crystal-controlled oscillator C. A quartz crystal filter D. A triggered multivibrator
79. A 10% increase in the frequency of a constant-width pulse train should cause what change in its average value? A. –10 %
B. –1 % C. +1 % D. +10 %
80. Two different signals can be coherent if they A. Have the same amplitude
B. Are both sine waves of different frequencies
C. Originate in the same physical equipment simultaneously
D. Have the same frequency
81. A quadrature detector requires that A. Four gates bee provided
B. The inputs are coherent C. The inputs are incoherent D. The inputs are identical
82. In a phase-locked loop, the VCO is the abbreviation for A. Variable coherent output
B. VHF communication oscillator C. Voltage-controlled oscillator D. Vien-count oscillator (neutralized)
83. Identify an advantage, or advantages of a properly designed FM system.
A. Relative immunity to atmospheric noise (lightning) B. Reduced bandwidth required
C. No noise of any kind
D. The noise figure is inversely proportional to the modulation index
84. The output of a balanced modulator A. LSB and USB
B. LSB C. USB D. Carrier
85. If the modulation index of an AM wave is changed from 0 to 1, the transmitted power is
A. Unchanged B. Halved C. Doubled
D. Increased by 50%
86. Which of the following is not a baseband signal of modulation?
A. Audio signal B. Video signal C. RF carrier
D. Binary coded pulses
87. If the unmodulated level peak carrier amplitude is doubled in an AM signal, the perfect modulation is ________.
A. 20 B. 50 C. 100 D. 200
88. Balanced modulator circuit when inserted in the equivalent suppresses the ___________
A. Carrier
B. Upper sideband C. Lower sideband
D. Baseband signal
89. The carrier of a 100% modulated AM wave is suppressed, the percentage power saving is __.
A. 100 % B. 50 % C. 83 % D. 66.66 %
90. If the modulation index if an AM wave is doubled, the antenna current is also doubled, the AM system being used is
A. H3E B. J3E C. C3F D. A3E
91. 100% modulation in AM means a corresponding increase in total power by _______.
A. 100 % B. 50 % C. 75 % D. 25 %
92. A single-tone amplitude modulated wave has _______. A. 2 components
B. 3 components C. 4 components D. 2n + 1 components
93. A carrier signal has ________. A. Constant peak amplitude
B. Frequency range of 20 – 20,000 Hz C. A varying amplitude
D. The information
94. The modulating system is _________ if the modulating frequency is doubled, the modulation index is halved, and the modulating voltage remains constant.
A. Amplitude modulation B. Phase modulation C. Frequency modulation D. Pulse modulation
95. What is the modulation index of an FM signal if its modulating frequency is doubled?
A. No effect
B. Twice the original index C. Four times the original index D. One-half the original index
96. An AM transmitter is rated 1000 W at 100% modulation. How much power required for the carrier?
A. 1000 W
B. 666.6 W C. 333.3 W D. 866.6 W
97. Standard way of designating AM A. A3E
B. B3E C. AHE D. C3F
98. _____ is the circuit used to detect frequency modulated signal.
A. Discriminator B. Modulator C. Modem D. Detector
99. _____ is an information signal that is sent directly without modulating any carrier.
A. C-band B. Q-band C. Baseband D. Broadband
100. Both frequency and phase modulation utilize ______ modulation. A. Digital B. Phase C. Amplitude D. Angle ANSWER
51. Distortion and splatter 52. Increase 53. 50 % 54. Increase 55. 767 mA 56. sq. root of 2 57. 1002.5 kHz 58. 1199.3 kHz 59. Both A and C 60. 10 MHz 61. Both A and B 62. Rectification 63. Distortion 64. Heterodyning 65. Both B and C 66. Angle modulation 67. Amplitude 68. Frequency deviation 69. -5 kHz 70. 5 71. All of these 72. Varactor diode 73. Direct FM 74. VCO 75. Multiplication 76. Foster-Seeley discriminator 77. Both B and C 78. A triggered multivibrator 79. +10 %
80. Have the same frequency 81. The inputs are coherent 82. Voltage-controlled oscillator
83. Relative immunity to atmospheric noise (lightning) 84. LSB and USB 85. Increased by 50% 86. RF carrier 87. 100 88. Carrier 89. 66.66 % 90. J3E 91. 50 % 92. 3 components
93. Constant peak amplitude 94. Frequency modulation 95. One-half the original index 96. 666.6 W
97. A3E 98. Discriminator 99. Baseband 100. Angle
(1) The first symbol indicates the type of modulation on the transmitter carrier.
A—Amplitude modulation, double sideband with identical information on each sideband.
F—Frequency modulation. G—Phase modulation.
J—Single sideband with suppressed carrier. P—Unmodulated pulse.
W—Cases not covered above, in which an emission consists of the main carrier modulated, either simultaneously or in a pre-established sequence, in a combination of two or more of the following modes: amplitude, angle, pulse.
(2) The second symbol indicates the type of signal modulating the transmitter carrier.
0—No modulation.
1—Digital modulation, no subcarrier. 2—Digital modulation, modulated subcarrier. 3—Analog modulation.
(3) The third symbol indicates the type of transmitted information.
A—Telegraphy for aural reception. B—Telegraphy for machine reception. C—Facsimile.
D—Data, telemetry, and telecommand. E—Voice.
N—No transmitted information. W—Combination of the above.
(b) Authorizations to use A3E, F3E, or G3E emission also include the use of emissions for tone signals or signaling devices whose sole functions are to establish and to maintain communications, to provide automatic station identification, and for operations in the Public Safety Pool, to activate emergency warning devices used solely for the purpose of advising the general public or emergency personnel of an impending emergency situation.
(c) The use of F3E or G3E emission in these services will be authorized only on frequencies above 25 MHz.
(d) Except for Traveler's Information stations in the Public Safety Pool authorized in accordance with § 90.242, only J3E emission will be authorized for telephony systems on frequencies below 25 MHz.
(e) For non-voice paging operations, only A1A, A1D, A2B, A2D, F1B, F1D, F2B, F2D, G1B, G1D, G2B, or G2D emissions will be authorized.
(f) For radioteleprinter operations that may be authorized in accordance with § 90.237, only F1B, F2B, G1B or G2B emissions will be authorize above 25 MHz, and A1B or A2B emissions below 25 MHz.
(g) For radiofacsimile operations that may be authorized in accordance with § 90.237, only F3C or G3C emissions will be authorized above 25 MHz, and A3C emissions below 25 MHz.
(h) [Reserved]
(i) For telemetry operations, when specifically authorized under this part, only A1D, A2D, F1D, or F2D emissions will be authorized.
(j) For call box operations that may be authorized in accordance with § 90.241, only A1A, A1D, A2B, A2D, F1B, F1D, F2B, F2D, G1B, G1D, G2B, G2D, F3E or G3E emissions will be authorized.
(k) For radiolocation operations as may be authorized in accordance with subpart F, unless otherwise provided for any type of emission may be authorized upon a satisfactory showing of need.
(l) For stations in the Public Safety and Industrial/Business Pools utilizing digital voice modulation, in either the scrambled or unscrambled mode, F1E or G1E emission will be authorized. Authorization to use digital voice emissions is construed to include the use of F1D, F2D, G1D, or G2D emission subject to the provisions of § 90.233.
(m) For narrowband operations in a 3.6 kHz maximum authorized bandwith, any modulation type may be used which complies with the emission limitations of § 90.209. (n) Other emissions. Requests for emissions other than those listed in paragraphs (c) through (e) of this section will be considered on a case-by-case basis to ensure that the requested emission will not cause more interference than other currently permitted emissions.
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
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 super heterodyne 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 super heterodyne 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 super heterodyne 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
151. An effect in which, the modulation of an unwanted signal is transferred to the desired carrier.
A. Crossmodulation B. Intermodulation C. Modulation mixing
D. Image-channel interference
152. Leads should be kept as short as possible in radio circuit so that
A. Skin effect is reduced B. There is less hysteresis effect C. There is less dielectric loss D. Stray coupling is minimized
153. The number of voice transmissions that can be packed into a given frequency band for amplitude-compandored single-sideband systems over conventional FM-phone systems.
A. 2 B. 18 C. 16 D. 4
154. Neutralization of an RF amplifier stage can be necessary in order to
A. Increase the amplifier’s gain
B. Prevent the generation of spurious oscillations C. Reduce the amplifier’s gain
D. Reduce the level of the output harmonics
155. The ability of a communications receiver to perform well in the presence of strong signals outside the band of interest is indicated by what parameter?
A. Blocking dynamic range B. Noise figure
D. Audio output
156. Stages that are common to both AM and FM receivers A. Tuner, local oscillator, detector, AF amplifier
B. RF amplifier, mixer, IF amplifier, AF amplifier
C. Local oscillator, RF amplifier, frequency discriminator, detector
D. Tuner, IF amplifier, detector, AF amp
157. Occurs during CW reception if too narrow a filter bandwidth is used in the IF stage of a receiver
A. Filter ringing
B. Undesired signals will reach the audio stage C. Output-offset overshoot
D. Cross-modulation distortion
158. What stage mainly determines a communication receiver’s sensitivity?
A. IF amplifier B. Mixer stage C. Detector stage D. RF amplifier
159. What is the main advantage of FM over AM? A. Better signal-to-noise-ratio
B. Narrower bandwidth C. Greater propagation range
D. Total freedom from adjacent-channel interference 160. An amplitude modulation created in an amplifier before the final RF stage.
A. Low-level modulation B. High-level modulation C. Direct modulation D. Indirect modulation
161. Receiver desensitizing can be reduced by A. Increasing the transmitter audio gain B. Decreasing the receiver squelch gain C. Increasing the receiver bandwidth
D. Ensuring good RF shielding between the transmitter 162. In a narrow-band FM system, the deviation ratio is commonly one and the highest audio frequency is generally limited to
A. 300 Hz B. 10,000 Hz C. 3,000 Hz D. 7,500 Hz
163. A type of emission is produced when an amplitude modulated transmitter is modulated by a facsimile signal A. A3F
B. F3F C. A3C D. F3C
164. Where is the noise generated which primarily determines the signal to noise ratio in a VHF (150 MHz) marine band receiver?
A. In the detector B. In the atmosphere
C. In the ionosphere D. In the receiver front end
165. Cross-modulation in a receiver can be reduced by A. Installing a filter at the receiver
B. Using a filter at the receiver
C. Increasing the receiver’s RF gain while decreasing the AF
D. Adjusting the pass-band tuning
166. What is the emission designation for FM telephony? A. F3E
B. G3E C. J3E D. H3E
167. What is the cause of receiver desensitizing?
A. The presence of a strong signal on a nearby frequency B. Audio gain adjusted too low
C. Squelch gain adjusted too high D. Squelch gain adjusted too low
168. In a phase-modulated signal (indirect FM), the frequency deviation is directly proportional to the
A. Carrier amplitude only
B. Amplitude of the modulating tone and frequency of the carrier
C. Carrier frequency only
D. Modulating signal amplitude only
169. An RF stage precedes the mixer stage in a superheterodyne receiver. One advantage of including this RF stage is
A. Better selectivity B. Better rejection ratio C. Greater sensitivity
D. Improved signal-to-noise-ratio
170. Two factors that determine the sensitivity of a receiver. A. Dynamic range and third-order intercept
B. Cost and availability C. Bandwidth and noise figure
D. Intermodulation distortion and dynamic range
171. What is an undesirable effect of using too-wide a filter bandwidth in the IF section of a receiver?
A. Undesired signals will reach the audio stage B. Output-offset overshoot
C. Thermal-noise distortion D. Filter ringing
172. A system containing a limiter stage, a discriminator, and a de-emphasis circuit?
A. Direct FM transmitter B. Indirect FM transmitter C. Single sideband AM receiver D. FM receiver
173. The limiter stage of an FM receiver
A. Prevents any amplitude modulation of the IF signal B. Limits the amount of frequency deviation in the IF signal C. Limits the overall bandwidth of the IF stages
D. Corrects any deviation in carrier frequency
174. High selectivity occurs when the degree of coupling between a receiver’s RF stages is
A. Tight B. Loose C. Critical
D. Adjusted for maximum power transfer
175. A carrier is phase modulated by a test tone. If the amplitude and the frequency of the tone are both doubled, the amount of the deviation is
A. Doubled B. Unchanged C. Halved
D. Multiplied by four
176. The degree of selectivity desirable in the IF circuitry of a single-sideband receiver.
A. 1 kHz B. 2.4 kHz C. 4.2 kHz D. 4.8 kHz
177. The component most apt to break down in the radio circuit is the
A. Crystal B. Resistor C. Transformer D. Diode
178. The base in an RF amplifier is grounded in order to A. Avoid the requirement of neutralizing the stage B. Raise the input impedance
C. Lower the output impedance D. Obtain maximum power output
179. The AM detector performs two basic functions in the receiver.
A. Rectifies and filters B. Amplifiers and filters C. Buffer and amplifier D. Buffer and detector
180. A varactor diode can be used in a/an A. Direct FM modulator circuit
B. AFC circuit in a direct FM transmitter C. Phase-modulator circuit
D. All of these
181. Receiver interference is not reduced by including a/an A. Crystal filter
B. Insulating enclosures around the receiver C. Wave trap
D. RF stage
182. What is the emission C3F? A. RTTY
B. SSB C. Television D. Modulated CW
RF power amplifier stage in an unmodulated carrier transmitter when the PEP output is 500 W?
A. Approximately 1000 W B. Approximately 800 W C. Approximately 250 W D. Approximately 600 W
184. Which of the following stages in an FM receiver is responsible for drastically reducing the effect of static noise during the reception of a signal
A. De-emphasis circuit B. Mixer stage C. Squelch circuit D. Limiter stage
185. The letters “SSSC” stands for A. Single sideband, single carrier B. Suppressed sideband, single channel C. Suppressed sideband, single carrier D. Single sideband, suppressed carrier
186. For many types of voices, what is the ratio of PEP-to-average power during a modulation peak in a single-sideband phone signal?
A. Approximately 1.0 to 1 B. Approximately 25 to 1 C. Approximately 100 to 1 D. Approximately 2.5 to 1
187. In most mixers, the oscillator frequency is ______ than the carrier frequency of the input signal.
A. Higher B. Lower C. The same D. 10 kHz above
188. Features of a transmitter’s buffer stage include A. High stage
B. Harmonic generation
C. Improvement in frequency stability of the oscillator D. Low input impedance
189. Type of emission produced when an amplitude modulated transmitter is modulated by a television signal A. F3F
B. A3C C. F3C D. A3F
190. A network is
A. A network consisting entirely of four inductors or four capacitors
B. A power incidence network
C. An antenna matching network that is isolated from ground
D. A network consisting of one inductor and two capacitors 191. How is G3E FM-phone signals produced?
A. A network consisting modulator on the audio amplifier B. With a reactance modulator on the final amplifier C. With a reactance modulator on the oscillator
D. With a balanced modulator on the oscillator
192. A way of eliminating auto interference to radio reception
A. Installing resistive spark plugs B. Installing capacitive spark plugs
C. Installing resistors in series with the spark plugs D. Installing two copper-braid ground strips 193. The carrier in an AM transmitter is the
A. Transmitter’s output signal when the modulation is present
B. Transmitter’s output signal when the modulation is zero C. Output signal from the crystal oscillator
D. RMS value of the AM signal
194. What stage feeds the discriminator of an FM receiver? A. Local oscillator
B. Mixer stage
C. Final IF amplifier, which also acts as a limiter stage D. Buffer
195. In an FM receiver, the stage that has the IF signal is input and the audio signal output.
A. Limiter B. Audio amplifier C. IF amplifier D. Discriminator
196. What is capture effect?
A. All signals on a frequency are demodulated by an FM receiver
B. The loudest signal received is the only demodulated signal
C. All signals on a frequency are demodulated by an AM receiver
D. The weakest signal received is the only demodulated signal
197. A double-sideband phone signal can be generated by A. Feeding a phase-modulated signal into a low-pass filter B. Modulating the plate voltage of a class-C amplifier C. Using a balanced modulator followed by a filter D. Detuning a Hartley oscillator
198. Pre-emphasis is used in FM transmitters to improve the signal-to-noise ratio of
A. High modulating frequencies B. Low modulating frequencies C. All modulating frequencies D. Frequencies carrier
199. The result of cross-modulation is that
A. The modulation of an unwanted signal is heard on the desired signal
B. A decrease in modulation level of transmitted signals C. Of receiver quieting
D. Of inverting sidebands in the final stage of the amplifier 200. Which of the following contains de-emphasis circuit? A. FM transmitter B. FM receiver C. VHF transmitter D. VHF receiver 101. Bandwidth 102. H3E 103. Continuous modulation 104. Pulse modulation 105. Coefficient of modulation 106. Carrier shift
107. The oscillator is crystal-controlled 108. Frequency translation 109. Balanced modulator 110. Both B and C 111. 30.8 MHz 112. 0.6 radian 113. Nonlinear 114. Push-push 115. Frequency synthesizer 116. 4 117. Balanced modulator 118. Indirect 119. All of these
120. The change of the crystal oscillator frequency by loading 121. Indirect FM
122.
123. Both A and B 124. TRF
125. Weak antenna signals
126. Bandwidth variations over the tuning range 127. Modulator
128. R–F amplifier 129. Mixer
130. Frequency translation 131. Internal noise
132. Reduction of receiver internal noise 133. Smaller
134. Noise figure 135. 120.1 MHz 136. 88.5 MHz
137. The image rejection ratio 138. Powdered iron 139. Skirt steepness 140. AGC 141. Squelch 142. Noise blanker 143. SBB voice
144. The audio voice information
145. An increase of the oscillator frequency 146. The noise floor of the receiver
147. Open circuit in the AGC’s filter capacitor 148. Cross-modulation interference
149. Limits the amplitude of the IF signal to the required level 150. Connecting a capacitor between the B+ and lead ground 151. Crossmodulation
152. Stray coupling is minimized 153. 4
154. Prevent the generation of spurious oscillations 155. Blocking dynamic range
156. RF amplifier, mixer, IF amplifier, AF amplifier 157. Filter ringing
158. IF amplifier
159. Better signal-to-noise-ratio 160. Low-level modulation
161. Ensuring good RF shielding between the transmitter 162. 3,000 Hz
163. A3C
164. In the receiver front end 165. Installing a filter at the receiver 166. F3E
167. The presence of a strong signal on a nearby frequency 168. Amplitude of the modulating tone and frequency of the carrier 169. Better rejection ratio
170. Bandwidth and noise figure
171. Undesired signals will reach the audio stage 172. FM receiver
173. Prevents any amplitude modulation of the IF signal 174. Loose
175. Multiplied by four 176. 2.4 kHz 177. Resistor
178. Avoid the requirement of neutralizing the stage 179. Rectifies and filters
180. All of these
181. Insulating enclosures around the receiver 182. Television
183. Approximately 1000 W 184. Limiter stage
185. Single sideband, suppressed carrier 186. Approximately 2.5 to 1
187. Higher
188. Improvement in frequency stability of the oscillator 189. A3F
190. A network consisting of one inductor and two capacitors 191. With a reactance modulator on the oscillator
192. Installing resistive spark plugs
193. Transmitter’s output signal when the modulation is zero 194. Final IF amplifier, which also acts as a limiter stage 195. Discriminator
196. The loudest signal received is the only demodulated signal 197. Modulating the plate voltage of a class-C amplifier 198. High modulating frequencies
199. The modulation of an unwanted signal is heard on the desired signal 200. FM receiver 201. What is emission F3F? A. AM B. Facsimile C. Television D. RTTY
202. What type of emission is produced when a frequency modulated transmitter is modulated by a facsimile signal? A. F3C
B. A3C C. F3F D. A3F
203. Two AM transmitting antennas are close together. As a result the two modulated signals are mixed in the final RF
stage of both transmitters. What is the resultant effect on other station?
A. Harmonic interference B. Intermodulation interference C. Spurious interference D. Crossmodulation interference
204. The term used to refer to the reduction of receiver gain caused by the signal of a nearby station transmitter in the same frequency band?
A. Quieting
B. Cross-modulation interference C. Squelch gain rollback
D. Desensitizing
205. What is the bandwidth occupied by the carrier, both sidebands and harmonics?
A. Authorized bandwidth
B. Bandwidth of emission and occupied bandwidth C. Operating bandwidth
D. All of these
206. A class-C RF amplifier is collector amplitude modulated and its average dc level collector current does not change. This means
A. A normal condition
B. Excessive drive to the base C. Insufficient drive to the base D. Insufficient audio modulation
207. What determines the percentage modulation of an FM transmitter?
A. Amplitude of the carrier B. Modulating frequency C. Carrier frequency
D. Amplitude of the modulating signal
208. Deviation ratio of an FM transmitter is the ratio of the A. Maximum frequency swing to the highest modulating frequency
B. Operating frequency of the assigned frequency C. Frequency swing to the modulating frequency
D. Highest modulating frequency to the minimum frequency 209. The main purpose of the beat frequency oscillator (BFO) is to generate
A. A 1 kHz not for Morse reception
B. Aid in the reception of weak voice-modulated signals C. An output, whose frequency differs from the IF by 1 kHz D. A signal, whose frequency is the same as intermediate frequency
210. Normally, a linear class BRF power amplifier operates with a bias approximately equal to
A. Twice cut-off
B. Ten times cut-off value C. 50% of cut-off value D. Projected cut-off
211. The purpose why an RF amplifier is operated under linear class-B conditions (as opposed to class-C) is to
A. Generate only even harmonics B. Generate only odd harmonics C. Increase the efficiency D. Amplify of an AM signal
212. The term used to refer to the condition where the signal from a very strong station are superimposed on other signal being received.
A. Cross-modulation interference B. Intermodulation distortion C. Receiver quieting D. Capture effect
213. _________ is the amplitude of the maximum negative excursion of a signal as viewed on an oscilloscope.
A. Peak-to-peak voltage B. Inverse peak positive voltage C. RMS voltage
D. Peak negative voltage
214. The type of emission that suffer most from selective fading.
A. CW and SSB B. SSB and TV
C. FM and double sideband AM D. SSTV and CW
215. In an FM-phone signal, ________ is the ratio between the actual frequency deviation to the maximum frequency deviation.
A. FM compressibility B. Modulating index
C. Percentage of modulation D. Quieting index
216. _______ is used to refer to the reception blockage of one FM-phone signal by another FM-phone signal.
A. Capture effect B. Desensitization
C. Cross-modulation interference D. Frequency discrimination
217. A receiver selectivity of 10 kHz in the IF circuitry is optimum for what type of signals?
A. SSB voice B. Facsimile C. FM
D. Double-sideband AM
218. If the envelope of modulation is constant in amplitude this means
A. Zero beat B. Under-modulation C. Zero-modulation D. Over-modulation
219. What is the approximate bandwidth of an FM with a modulation factor of 12.5 and a modulating frequency of 10 kHz?
A. 20 kHz B. 270 kHz
C. 250 kHz D. 45 kHz
220. Amplitude modulation is the same as A. Linear mixing
B. Analog multiplication C. Signal summation D. Multiplexing
221. The negative half of the AM wave is supplied by a/an _______ on a diode modulator.
A. Tuned circuit B. Transformer C. Capacitor D. Inductor
222. One of the following can produce AM. A. Having the carrier vary a resistance
B. Having the modulating signal vary a capacitance C. Varying the carrier frequency
D. Varying the gain of an amplifier
223. Amplitude modulators that vary the carrier amplitude with the modulating signal by passing it through an attenuator network is the principle of
A. Rectification B. Amplification C. Variable resistance D. Absorption
224. Which component is used to produce AM at very high frequencies?
A. Varactor diode B. Thermistor C. Cavity resonator D. PIN diode
225. A collector modulator has a supply voltage of 48 V. What is the peak-to-peak amplitude of the modulating signal for 100 percent modulation?
A. 24 V B. 48 V C. 96 V D. 120 V
226. What circuit recovers the original modulating information from an AM signal?
A. Modulator B. Demodulator C. Mixer D. Crystal set
227. What is the most commonly used amplitude demodulator?
A. Envelope detector B. Balanced modulator C. Mixer
D. Crystal set
228. What circuit generates the upper and lower sidebands and suppresses the carrier?
A. Amplitude modulator
B. Diode detector C. Class C amplifier D. Balanced modulator
229. _________ is a widely used balanced modulator. A. Diode bridge circuit
B. Full-wave bridge rectifier C. Lattice modulator
D. Balanced bridge modulator
230. In a diode ring modulator, the diodes act like A. Variable resistors
B. Switches C. Rectifiers
D. Variable capacitors
231. The output of a balanced modulator is A. AM
B. FM C. SSB D. DSB
232. The principal circuit in the popular 1496/1596 IC balanced modulator is a
A. Differential amplifier B. Rectifier
C. Bridge
D. Constant current source
233. The most commonly used filter in SSB generators uses
A. LC networks
B. Mechanical resonators C. Crystals
D. RC networks and op amps
234. In the phasing method of SSB generation, one sideband is canceled out due to
A. Phase shifting B. Sharp selectivity C. Carrier suppression D. Phase inversion
235. A balanced modulator used to demodulate a SSB signal is call a/an
A. Transponder B. Product detector C. Converter D. Remodulator
236. Frequency translation is done with a circuit called a A. Summer
B. Multiplier C. Divider D. Mixer
237. Mixing for frequency conversion is the same as A. Rectification
B. AM
C. Linear summing D. Filtering
238. Which of the following is not a major advantage of FM over AM?
A. Greater efficiency B. Noise immunity C. Capture effect
D. Lower complexity and cost
239. The primary disadvantage of FM is its A. Higher cost and complexity
B. Excessive use of spectrum space C. Noise susceptibility
D. Lower efficiency 240. Noise is primarily A. High-frequency spikes B. Lowe-frequency variations C. Random level shifts
D. Random frequency variations
241. The receiver circuit that rids FM of noise is the A. Modulator
B. Demodulator C. Limiter D. Low-pass filter
242. The AM signals generated at a low level may only be amplified by what type of amplifier?
A. Class A B. Class B C. Class C D. All of the above 243. SSB means
A. Single sideband with suppressed carrier B. Single sideband with carrier
C. Double sideband with no carrier D. Single sideband with reduced carrier
244. A circuit used to select the desired output from a mixer A. Transformer
B. Resonant circuit C. Filter
D. Phase-shift circuit
245. What is the output of a balanced modulator? A. AM
B. DSB C. SSB D. ISB
246. The acronym SSSC refer to A. Suppressed sideband, single carrier B. Suppressed sideband, suppressed carrier C. Single sideband, suppressed carrier D. Single sideband, single carrier
247. Which process occurs in the receiver? A. Demodulation
B. Reception C. Modulation D. Recreation
signal? A. PLL B. BFO
C. Ratio detector D. All of these
249. Which of the following is the most widely used amplitude modulator
A. Diode detector B. PLL circuit C. VCO D. All of these
250. Which of the following is the most widely used balanced modulator
A. Full-wave bridge circuit B. Balanced bridge modulator C. Lattice modulator
D. None of these
251. A method that applied the modulated wave to the vertical deflection circuit of the oscilloscope and the modulating signal to the horizontal deflection circuit. a. Trapezoidal method
b. Circular method c. Square method d. Any method
252. The heart of all methods of single-sideband modulation and demodulation
a. Modulator
b. Balanced modulator c. Modulation
d. demodulation
253. If the frequency and phase are parameters of carrier angle, which is a function of time, the general term ___________-cover both.
a. Amplitude modulation b. Frequency modulation c. Phase modulation d. Angle modulation
254. In FM radio communication system, narrow-band (NBFM) is used rather than wideband (WBFM), because it, a. Improves signal to noise ration
b. Reduces interchannel interference
c. Provides maximum coverage for a given amount of power
d. All of the above
255. Radio transmitter basically consists of two principal parts, one reproducing a carrier frequency and one for __________.
a. IF Frequency b. RF Frequency c. Modulating Frequency d. Power
256. Is a measure of its ability to maintain as nearly a fixed frequency as possible over as long as time interval as
possible.
a. Receiver Noise Factor b. Selectivity
c. Sensitivity
d. Frequency stability
257. Is the effect of two-transmitter when they are in close proximity. This results into the sum and difference frequencies of two carriers.
a. Intermodulation effect b. Intermodulation interference c. Intermodulation product d. intermodulation
258. _________ is a continuous frequency capable of being modulated or impressed with a second information carrying signal.
a. Carrier frequency b. Center frequency c. IF frequency d. RF frequency
259. The varactor diode used in FM may be represented by the approximate equivalent circuit of the _____ in series with a ________.
a. Diode, capacitor b. Diode, resistor c. Capacitor, resistor d. Any of these
260. The name varactor comes from variable _________. a. Resistor
b. Capacitor c. Diode d. reactor
261. 75 microseconds pre-emphasis time is used in __________.
a. FM b. AM c. TV
d. None of these
262. Recovers the modulating voltage from the frequency modulation by utilizing the phase angle shift between primary and secondary voltages of tuned oscillators. a. Direct method
b. Indirect method
c. Foster-Seeley discriminator d. Slope detector
263. Is used in FM receivers to “lock onto” the received signal and stabilized receptions.
a. Automatic Gain Control b. Automatic Frequency Control c. Muscle Control
d. Automatic Frequency Gain Control
264. Are amplifier circuits that are used to eliminate amplitude modulation and amplitude-modulated noise from received FM Signals before detection.
a. Demodulators b. Diode detector c. Amplitude limiters d. None of these
265. If the total sideband power is 12.5% of the total radiated power, find the modulation index.
a. 50 percent b. 53.4 percent c. 26.2 percent d. 32.3 percent
266. Carriers are spaced at 20 kHz, beginning at 100 kHz. Each carrier is modulated by a signal with a 5 kHz bandwidth. Is there interference from the sideband? a. Yes
b. No c. Maybe d. Secret
267. For an unmodulated carrier of 150 V and a modulated peak value of 230 V. What is the modulation index
a. 0.35 b. 0.533 c. 0.652 d. 0.42
268. New frequencies outside the regular AM spectrum are called ___________.
a. Distortion b. Interference c. Splatter d. Harmonic
269. A DSB-SC has a total power of 350 watts with 100% modulation suppresses 50% of the carrier, and the suppressed carrier power goes to the sidebands. How much power is in the sidebands?
a. 116.67 W b. 233.33 W c. 175 W d. 350 W
270. A DSB-SC system must suppress the carrier by 30 dB from its original value of 30 W. What value must the carrier be reduced?
a. 30000 W b. 0.03 W c. 300 W d. 0.003 W
271. ___________, which further amplifies the signal and has the bandwidth and passband shaping appropriate for the received signal.
a. RF stage
b. Mixer and local oscillator stage c. IF stage
d. AF stage
272. In FM, a bandwidth estimate 98 percent level of Bessel functions
a. Approximate bandwidth b. Narrow-band Bandwidth c. Carson’s rule
d. Wideband bandwidth
273. The complete series of stages for reproducing the FM signal with the desired carrier and deviation is the _______. a. Modulator
b. Exciter c. IF stage d. RF stage
274. Is the ability of FM system to provide low-noise, high fidelity music background/broadcast..
a. Monophonic b. Stereophonic c. Stereonic d. SCA
275. It make use of the shape of IF filter frequency response roll-off versus frequency.
a. Foster Seeley b. Slope detector c. Diode detector d. Quadrature detector
276. In AM, modulation index is a number lying between ____ and 1.
a. 2 b. 5 c. 0 d. 3
277. This form of modulation is also known as independent sideband emission.
a. A3E b. R3E c. H3E d. B8E
278. An attenuated carrier is reinserted into the SSB signal to facilitate receiver tuning and demodulation.
a. A3E b. R3E c. H3E d. B8E
279. Standard AM used for broadcasting a. A3E
b. R3E c. H3E d. B8E
280. Single sideband, suppressed carrier in which the carrier is suppressed by at least 45 dB in the transmitter. a. A3E
b. R3E c. H3E d. B8E
281. The shift in the carrier frequency from the resting point compared to the amplitude of the modulating signal is
called _______. a. Index
b. Deviation ratio c. Carrier frequency d. Deviation frequency
282. In FM, the amplitude of the modulated frequency wave remains ___________ at all times.
a. Varying b. Dependent c. Constant d. variable
283. An AM has a maximum span of 30 V, what is the required minimum span to attain 100% modulation? a. 30 V
b. 20 V c. 0 V
d. None of these
284. DZMM having a carrier frequency of 630 kHz is modulated by 2.6 kHz audio signal having an amplitude of 37.5 V. What is the amplitude voltage of 630 kHz carrier frequency at 0.35 modulation index?
a. 57.6 V b. 107.14 V c. 206.5 V d. 86.2 V
285. If the sideband power is 50% of the carrier power, what is the modulation index?
a. 50% b. 75% c. 90% d. 100%
286. If the increase power is 180 watts at 1 kW unmodulated output power the modulation index is _________.
a. 75% b. 60% c. 50% d. 25%
287. In AM, if the unmodulated power carrier is 10 kW, and the total power is 15 kW, what is the upper sideband power at 100% modulation index?
a. 25 kW b. 2 kW c. 2.5 kW d. 4 kW
288. If the input resistance of the base station of AM broadcast produced 20 kW carrier power, at what modulation index should the antenna rise at 108.63 A? a. 20%
b. 50% c. 60% d. 80%
289. ________ used a phase detector to compare the
phase and frequency of the received signal to the VCO output.
a. PIL b. PAL c. PLL d. PLI
290. A filter with a roll-off of 6 dB/kHz is used as a slope detector. The input signal varies with +3 kHz deviation from center carrier frequency. How many dB down is the output at full deviation?
a. 9 dB b. -18 dB c. 18 dB d. -9 dB
291. A receiver limiter requires a 20 mV signal for quieting operation. The voltage gain between the RF input and the limiter is 57.7 dB, what is the input at the antenna terminal assuming equal resistance?
a. 75.6 mV b. 26.67 uV c. 52.3 uV d. 49.6 uV
292. A 1-MHz carrier is modulated with a resulting 100 Hz deviation. It undergoes x36 multiplication, followed by mixing with a 34.5 MHz signal and re-multiplication by 72. What is the final carrier and deviations?
a. 5076 MHz, ± 2592 MHz b. 2592 MHz, ± 259.2 kHz c. 2592MHz, ± 5076 MHz d. 259.2 MHz, ± 108 kHz
293. For standard commercial broadcast FM, the deviation ratio is ________.
a. 15 b. 75 c. 5 d. 10
294. A system has 150 kHz of bandwidth available for 10 kHz modulation signal. What is the approximate deviation to be used?
a. 35 kHz b. 65 kHz c. 25 kHz d. 15 kHz
295. An FM has a deviation of 100 kHz and a modulating frequency of 15 kHz, what happen to m if the deviation triples?
a. 6.66 b. 2.22 c. 4.12 d. 0.20
296. A receiver for a signal at 100 MHz uses a 10.7 MHz IF and low tracking. What is the image frequency?
b. 78.6 MHz c. 52.5 MHz d. 35.2 MHz
297. What is the change in resonant frequency of the actual varactor capacitance value differs by -5% (0.05) of the nominal value?
a. 2.06 b. 3.02 c. 1.03 d. 5.06
298. An oscillator resonate at 1 MHz with a nominal 100 pF capacitor and 0.25 mH inductor, what s the resonant frequency of the actual capacitor value is +20% of the nominal value?
a. 1.006 MHz b. 0.9188 MHz c. 3.625 MHz d. 2.00123 MHz
299. “Front end” is also called _________. a. IF stage
b. AF stage c. RF stage d. None of these
300. Undesired signal on the other side of the local oscillator output will have the same difference frequency and pass into the IF amplifier.
a. Carrier frequency b. Sum frequency c. Difference frequency d. Image frequency 201. Television 202. F3C 203. Intermodulation interference 204. Desensitizing
205. Bandwidth of emission and occupied bandwidth 206. A normal condition
207. Amplitude of the modulating signal
208. Maximum frequency swing to the highest modulating frequency
209. An output, whose frequency differs from the IF by 1 kHz 210. Projected cut-off
211. Amplify of an AM signal 212. Cross-modulation interference 213. Peak negative voltage 214. FM and double sideband AM 215. Percentage of modulation 216. Capture effect 217. Double-sideband AM 218. Zero-modulation 219. 270 kHz 220. Linear mixing 221. The tuned circuit
222. Having the carrier vary a resistance 223. Variable resistance 224. PIN diode 225. 96 V 226. Demodulator 227. Envelope detector 228. Balanced modulator 229. Lattice modulator 230. Switches 231. DSB 232. Differential amplifier 233. Crystals 234. Phase shifting 235. Product detector 236. Mixer 237. Linear summing
238. Lower complexity and cost 239. Excessive use of spectrum space 240. High-frequency spikes
241. Limiter 242. Class C
243. Single sideband with suppressed carrier 244. Filter
245. DSB
246. Single sideband, suppressed carrier 247. Demodulation 248. BFO 249. Diode detector 250. Lattice modulator 251. Trapezoidal method 252. Balanced modulator 253. Angle modulation 254. All of the above 255. Modulating Frequency 256. Frequency stability 257. Intermodulation interference 258. Carrier frequency 259. Capacitor, resistor 260. reactor 261. FM 262. Foster-Seeley discriminator 263. Automatic Frequency Control 264. Amplitude limiters 265. 53.4 percent 266. No 267. 0.533 268. Splatter 269. 233.33 W 270. 0.03 W 271. IF stage 272. Carson’s rule 273. Exciter 274. Stereophonic 275. Slope detector 276. 0 277. B8E 278. R3E 279. A3E 280. H3E 281. Deviation ratio 282. Constant 283. 0 V 284. 107.14 V 285. 100% 286. 60% 287. 2.5 kW 288. 60% 289. PLL 290. 18 dB 291. 26.67 uV 292. 2592 MHz, ± 259.2 kHz 293. 5 294. 65 kHz 295. 0.20 296. 78.6 MHz 297. 1.03 298. 0.9188 MHz 299. RF stage 300. Image frequency
301. One of the following refers to an output of a balanced modulator
a. SSB b. ISB c. AM d. DSB
302. Which of the following components is used to produce AM at very high frequencies?
a. Cavity resonator b. PIN diode c. Varactor d. Thermistor
303. A third symbol emission which represent data transmission including telemetry, and telecommand a. B
b. D c. C d. N
304. In an AM wave, useful power is carried by a. None of these
b. Sidebands
c. Both the sidebands and the carrier d. Carrier
305. Determine the modulation index of an standard FM broadcast having a hypothetical maximum carrier frequency deviation of ±12 kHz and a maximum modulating frequency pf 4kHz.
a. 9 b. 6 c. 3 d. 4
306. The process by which the intelligence signals normally at lower frequency are removed from the transmission frequency after it is received in the receiver station.
a. Detection b. Demodulation c. Amplification d. Modulation
a. The squelching of a signal until a critical signal-to-noise ratio is reached
b. Carrier rejection through phase nulling c. A linear amplification mode
d. A mixing process whereby information is imposed upon a carrier
308. What is a balanced modulator?
a. An FM modulator that produces balance deviation b. A modulator that produces a DSBSC signal c. A modulator that produces a SSBSC signal d. A modulator that produces a full carrier signal 309. What is a reactance modulator?
a. A circuit that acts as a variable resistance or capacitance to produce FM signals
b. A circuit that acts as a variable resistance or capacitance to produce AM signals
c. A circuit that acts as a variable inductance or capacitance to produce FM signals
d. A circuit that acts as a variable inductance or capacitance to produce AM signals
310. How can an SSB phone signal be generated? a. By dividing product detector with a DSB signal b. By using a reactance modulator followed by a mixer c. By using a loop modulator followed by a mixer d. By using a balanced modulator followed by a filter 311. How can a DSB phone signal be generated?
a. By feeding a phase modulated signal into a low pass filter
b. By using a balanced modulator followed by a filter c. By detuning a Hartley oscillator
d. By modulating the plate voltage of a class C amplifier 312. First symbol in the designation of radio signals emission which refers to use of an unmodulated carrier.
a. J b. N c. H d. A
313. One of the following is a communications filter generally used in the transceiver of a single sideband generator.
a. Lowpass filter b. Crystal filter c. Bandpass filter d. Mechanical filter
314. What is the modulation index for an AM signal having Vmax and Vmin of 2.6 and 0.29, respectively?
a. 0.799 b. 0.111 c. 0.894 d. 0.639
315. What is the bandwidth of an AM signal modulated by a 15-kHz intelligence signal?
a. 7.5 kHz b. 15 kHz c. 30 kHz d. 60 kHz
316. If a transmitter supplies 10 kW to the antenna when it is unmodulated, determine the total radiated power when it is modulated at 30%
a. 10.45 watts b. 10750 watts c. 11.5 kilowatts d. 10450 watts
317. Which of the following waveform characteristics determines the wavelength of a sine wave?
a. Phase b. Amplitude c. Period d. Phase angle
318. In the F3E signal, what is the term for the ratio between the deviation of a frequency modulated signal and the modulating frequency?
a. FM compressibility b. Quieting index c. Modulation index
d. Percentage of modulation
319. Which frequency band is the standard AM radio broadcast?
a. HF b. UHF c. MF d. VHF
320. The letter-designation B8E is a form of modulation also known as
a. Pilot carrier system
b. Independent sideband emission c. Lincompex
d. Vestigial sideband transmission
321. What are the two general categories of methods for generating emission F3E?
a. The only way to produce an emission F3E signal is with reactance modulator on the oscillator
b. The only way to produce an emission F3E signal is with a balanced modulator on the oscillator
c. The only way to produce an emission F3E signal is with a balanced modulator on the audio amplifier
d. The only way to produce an emission F3E signal is with a reactance modulator on the final amplifier
322. 100% modulation in AM means a corresponding increase in total power by ____.
a. 25% b. 75% c. 100% d. 50%
323. How does the SSB transmitter output power normally
expressed? a. Average power
b. In terms of peak envelope power c. In terms of peak-to-peak power d. Peak power
324. Determine from the following the common use of DSB in broadcast and telecommunications
a. Satellite communication b. FM/TV stereo
c. Two-way communications d. Telephone systems
325. What is the source of sidebands in frequency modulation?
a. Oscillator
b. Baseband frequency c. Mixer
d. Carrier harmonics
326. What is the source of sidebands in frequency modulated voice?
a. A3F b. A3J c. F3E d. J3E
327. The third symbol in the designation of radio emission under the ITU refers to
a. Type of modulation of the main carrier b. Nature of signals
c. Type of information to be transmitted d. Nature of multiplexing
328. An AM transmission of 3 kW is 100% modulated. If it is transmitted as an SSB signal, what would be the total power transmitted?
a. 500 W b. 1000 W c. 1500 W d. 2000 W
329. This circuit has the function of demodulating the frequency-modulated signal. It is a
a. Automatic gain control b. Automatic frequency control c. Envelope detector
d. Foster-Seeley discriminator
330. Calculate the power in one sideband of an AM signal whose carrier power is 50 watts. The unmodulated current is 2 A while the modulated current is 2.4 A.
a. 22 W b. 33 W c. 11 W d. 44 W
331. The method of generating FM used by broadcasting station is
a. Direct b. All of these
