INTRODUCTORY TOPICS 1.. Which part of the sinewave expression cannot be varied in accordance with the low-frequency intelligence to create a modulated signal? a)phase b)frequency c)time d)amplitude 2. Communication systems are most often categorized by what characteristic? a) Modulation frequency b) Carrier frequency c) Transmission distance d) Information transmitted 3. Voltage gain in decibels is a) 10 ln V2/V1 b) 10 logv2/v1 c) 20 lnv2/v1 d) 20 log V2/V1 4. Which expression indicates a measurement using a 1-W reference? a) dbm b) db1 c) dbw d) db(w) 5. An amplifier operating over a 2-Mhz bandwidth has a 75 ohm input resistance. If it is operating at 22 C and has a voltage gain of 300, the noise produced at the output of this amplifier would be approximately a) 128uV Eduspace.co.in 1
b) 7.33pV c) 1.56uV d) 469uV d) 6. Which of the following is not an example of external noise? a) Fluorescent light b) Solar emission c) Resistor noise d) Lightning 7. An amplifier's output signal has 25 mv p-p of desired signal mixed in with 45 uv rms of undesired noise. The load impedance is 50 ohm. What is the amplifier's output S/N level in db? a) 22.9 db b) 54.9 db c) 45.9 db d) 51.9 db 8.Why does a 5-kHz square wave require a greater bandwidth than a 2-kHz sinewave? a) The square wave has a larger frequency than the sine wave. b) The square wave has an infinite number of harmonics, whereas the sinewave has only one. c) The square wave is much easier to cover by noise. d) The square wave must also include an offset (dc) voltage, whereas the sinewave does not. 9. The relationship between information and bandwidth is called a) Information theory b) Fourier analysis c) FFT d) Hartley's law 10. Aliasing can be defined as errors occurring when a) The input frequency exceeds the sample rate. b) The bandwidth is less than the input frequency. Eduspace.co.in 2
c) The type of modulation has been incorrectly identified. d) The sampling signal has been incorrectly identified. 11.Which of the following does not hold true for a parallel resonant circuit? a) At the resonant frequency the impedance of the circuit is a minimum. b) If Q>10, the resonant frequency is the same as it would be if it were a series. c) It is commonly referred to as a tank circuit. d) At the resonant frequency, the circuit draws minimum current from the constant-voltage source. 12. The oscillator design that uses a third capacitor in the tank circuit for swamping out the effect of the transistor's internal capacitances is the a) Hartley design b) Clapp design c) Colpitts design d) Crystal design 13.The ability of a crystal to oscillate at its resonant frequency is due to a) The flywheel effect b) Barkhausen criteria c) The piezoelectric effect d) Frequency synthesis 14. The Barkhausen criteria has to do with a) Receiver noise b) Fourier analysis c) Oscillation d) Troubleshooting 15.Which of the following can be called a troubleshooting plan? a) Symptoms as clues to faulty stages Eduspace.co.in 3
b) Signal tracing and signal injection c) Voltage and resistance measure Substitution Fill in the blank 16. When discussing the radio-frequency spectrum, the abbreviation VF means frequency. a) video b) volume c) voice d) variable 17. A 600 ohm audio system has a 4-V output. That represents a -dbm (600) signal. a) 28.52 b) 14.26 c) 7.13 d) 0.713 18. A 0-dBW level is defined as with respect to a 1-W reference. a) 1 W b) 0 W c) 10 W d) 0.1W 19. Two other terms for thermal noise are and. a) Johnson; pink b) Watkins; pink c) Johnson; white d) Watkins; white 20.. The S/N ratio at the input of a device to its output S/N is called the. a) noise figure Eduspace.co.in 4
b) electrical noise c) excess noise d) noise ratio 21 The noise-measurement technique allows reasonably accurate readings using an oscilloscope. a) internal b) tangential c) external d) phosphur 22. `Representing a square wave using five harmonics introduces distortion than using three harmonics. a) Less b) More c) unlimited d) the same 23. A circuit that has a balance between inductive and capacitive reactance is said to be in. a) Sync b) Hysteresis c) Resonance d) trouble 24. A filter has a Q of when its loss is 3 db, f r = 3 MHz, and its BW is 60 khz. a) 5 0 b).02 c) 0.2 d) 50 25 A crystal oscillator specified at 100 khz with 20 ppm accuracy should never exceed khz. a) 99.998 b) 100.00 Eduspace.co.in 5
c) 2 99.98 d) 100.02 26. In a modulated system, the low-frequency intelligence signal is not called the a) Modulating signal b) Information signal c) Modulating wave d) Carrier 27. A 7.0-Mhz carrier is modulated by a voice signal that has three frequency components of 100 Hz, 200 Hz, and 300 Hz. What three frequencies comprise the lower sideband? a) 6.9997 Mhz, 6.9998 Mhz, and 6.9999 Mhz b) 100 Hz, 200 Hz, and 300 Hz c) 6.9999 Mhz, 7.0000 Mhz, and 7.0001 Mhz d) 7.0001 Mhz, 7.0002 Mhz, and 7.0003 Mhz 28. The total output power of an AM transmitter is measured to be 850 W. What is the total output sideband power if it has a percent modulation of 100%? a) 425 W b) 850 W c) 283.3 W d) 141.65 W 29. A 100-kHz carrier is modulated by a 20-Hz 2kHz signal. The upper sideband is a) 102 khz b) 100.02 khz to 102 khz c) 101 khz d) 100.002 khz to 102 khz 30. One full revolution of a phasor generates which percentage of a full sinewave? a) 25% Eduspace.co.in 6
b) 50% c) 100% d) 200% 31. An AM waveform at maximum is 100 V p-p and at minimum is 40 V p-p. The modulation percentage is a) 250% b) 40% c) 25% d) 37.5% 32. A transmitter having a 900-W carrier transmits 1188 W when modulated with a single sinewave. If the carrier is simultaneously modulated with another sinewave at 60% modulation, calculate the total transmitted power. a) 1084 W b) 1170 W c) 1350 W d) 1224 W 33. Low-level modulation is a) The most economic approach for low-power transmitters. b) Characterized by the use of "linear" power amplifiers to amplify the AM signal. c) Characterized by having the carrier and the intelligence signals mix at low power levels. 34. The main advantage of a high-level modulation system compared to a low-level system is that it a) Allows more efficient amplification. b) Allows use of low-powered intelligence signal. c) Provides higher modulation percentage. d) Is more economical. 35. What is the purpose of a buffer amplifier stage in a Eduspace.co.in 7
transmitter? a) It prevents transmitters from producing spurious frequencies in the output signals. b) It provides power amplification with high efficiency. c) Its high input impedance prevents oscillators from drifting off frequency. d) It amplifies audio frequencies before modulation occurs. 36. The purpose of an antenna coupler is to a) Match the output impedance of the transmitter with the antenna's impedance to provide maximum power transfer. b) Allow the transmitter to be connected to several antennas at the same time. c) Filter out the carrier frequency from the transmitter's AM output signal. d) Cause the transmitter to operate at more than one carrier frequency at the same time. 37. The main reason for using a dummy antenna is to a) Prevent damage to output circuits. b) Minimize damage to the regular antenna. c) Prevent overmodulation. d) Prevent undesired transmissions. 38. A spectrum analyzer is a) An instrument that displays amplitude versus frequency on a CRT. b) Often used to determine if a transmitter's output signal is free from any spurious signals. c) Can be thought of as a radio receiver with broad frequency range.. 39. The strategy for repair of electronic equipment includes the following. a) Verify that a problem exists. Eduspace.co.in 8
b) Isolate the defective stage. Isolate the defective component. c) Replace the defective component and hot check.. 40. A technique that helps you understand how a carrier and sideband combine to form the AM waveform is a) The tangential method. b) Phasor representation. c) Keying. d) None of the above. FILL IN THE BLANK 41. Direct transmission of intelligence signals without modulation would cause problems. a) interference b) static c) spurs d) keying 42. A nonlinear device is characterized by a nonlinear output versus relationship. a) noise b) gain c) bandwidth d) input 43. In AM, overmodulation creates frequencies a station's normal allocated range. a) within b) outside c) below d) around 44. In AM, 100% modulation indicates that % of the total transmitted power is in the sidebands. Eduspace.co.in 9
a) 50 b) 33.33 c) 25 d) 100 45. An AM transmitter transmits 200 W when modulated at 40%. The power in the lower sideband is W. a) 7.41 b) 14.82 c) 92.59 d) 85.18 46. The type of transistor modulator (base, emitter, or collector) is determined by where the is input. a) carrier b) intelligence c) dc d) ac 47. The use of a PIN-diode modulator is prevalent at frequencies. a) Audio b) elf c) microwave d) infrared 48. In a newly constructed transmitter, it is common to go through a(n) procedure to get it on the air. a) Examination b) Quality c) Keying d) Tune-up 49. When generating the trapezoid pattern, the intelligence signal is applied to the input of the oscilloscope. a) Vertical Eduspace.co.in 10
b) horizontal c) Z d) audio 50. When troubleshooting a high-powered transmitter, the most important consideration is. a) Output b) frequency c) safety d) noise 51. The main problem with the TRF design is a) Lack of selectivity in receiving all AM stations b) Poor demodulation of an AM station c) Frustration in tuning to receive more than one station d) Lack of sensitivity in receiving all AM stations 52. The sensitivity of a receiver has to do with its ability to a) Withstand shock b) Receive one station versus another c) Receive weak stations 53. When the input to an ideal nonlinear device is an AM waveform consisting of a carrier and its sidebands, the output of nonlinear mixing produces the original intelligence because a) The intelligence signal is one of its inputs. b) A dc component is also produced. c) The difference between the carrier and its sidebands is the original intelligence frequency. d) The intelligence frequencies are the upper and the lower sideband frequencies. 54. An AM signal having a carrier frequency of 940 khz is to be mixed with a local oscillator output signal in order to produce an intermediate frequency of 455 khz. At what should the L.O. Eduspace.co.in 11
frequency be set? a) 455 khz b) 1395 khz c) 910 khz d) 1850 khz 55.Diodes that have been specially fabricated to produce a capacitance that varies inversely proportional to the amount of reverse bias are called a) Varactor diodes b) Varicap diodes c) VVC diodes 56. The image frequency for a standard broadcast receiver using a 455-kHz IF and tuned to a station at 680 khz would be a) 1135 khz b) 225 khz c) 1590 khz d) 1815 khz 57. Double conversion is used to overcome the problem of a) Image frequency b) Tracking Diagonal c) clipping d) Poor sensitivity 58.An auxiliary AGC diode a) Reduces selectivity b) Increases sensitivity c) Decreases sensitivity 59. Which of the following would occur in a receiver not having AGC? Eduspace.co.in 12
a) The speaker output level would drastically change while tuning from a weak signal to a strong signal. b) Local stations would easily produce distorted signals in the speaker. c) There would be a constant need to readjust the volume control as the weather and ionosphere change. 60. The only roadblock to having a complete receiver manufactured on an integrated circuit is a) Tuned circuits and volume controls b) Cost c) Phase-locked loops d) Ceramic filters 61. The decibel difference between the largest tolerable receiver input signal and its sensitivity is called a) The decibel power gain of the receiver b) Automatic gain control (AGC) c) The dynamic range of the receiver d) The IF amplifier gain 62. The simplest AM detector is the a) Synchronous detector b) Product detector c) Heterodyne detector d) Diode detector 63. Tracking in a superhet receiver is accomplished using a a) Trimmer capacitor b) Padder capacitor c) Varicap diode d) a and b 64. If no stations are picked up on the lower half of the AM band, the likely problem is Eduspace.co.in 13
a) Low RF gain b) Poor AGC operation c) IF selectivity d) LO tracking 65. If no sound is heard from a receiver, the most likely problem area is the a) Power supply b) RF section c) Audio amplifier d) AGC diode FILL IN THE BLANK 66. A TRF receiver includes three stages: the RF,, and audio amplifier. a) IF b) detector c) trimmer d) mixer 67. The extent to which a receiver can differentiate between the desired signal and others is termed its. a) selectivity b) sensitivity c) figure-of-merit d) gain 68. AM detection requires a nonlinear device because a linear device create difference frequencies. a) helps b) only c) doesn't d) sometimes 69. A synchronous detector is able to produce distortion outputs. Eduspace.co.in 14
a) zero b) low c) high d) infinite 70. Another name for the is the first detector. a) mixer b) VCO c) oscillator d) diode 71. The padder and trimmer capacitors are used to facilitate in a superhet receiver. a) Alignment b) Sensitivity c) Images d) tracking 72. Image-frequency problems are reduced by using conversion systems. a) single b) double c) backward d) autodyne 73. The gain of a bipolar transistor can be controlled by varying the emitter current. a) Residule b) ac c) envelope d) dc 74. The use of a(n) AGC diode reduces receiver gain for very large signals. a) P-I-N Eduspace.co.in 15
b) varicap c) auxiliary d) point-contact 75. A quick test to determine if the audio amplifier is working is to touch a screwdriver to the center terminal of the. a) volume control b) power transistor c) trimmer capacitor d) padder capacitor 76. An SSB signal with a maximum level of 200 V p-p into a 50 ohm load results in a PEP rating of a) 200 W b) 50 W c) 100 W d) 800 W 77. State the chief advantage(s) of a standard SSB system. a) Maximum signal range with minimum transmitted power b) Easy carrier reinsertion c) Elimination of carrier interference d) a and c 78. The noise advantage of SSB over AM is a) 3 5 db b) 5 7 db c) 8 10 db d) 10 12 db 79. What is the difference between a balanced modulator and a regular modulator? a) There is no carrier produced in the output of a balanced modulator. b) In a balanced modulator, there is 180º phase shift between Eduspace.co.in 16
the upper and lower sidebands. c) In a balanced modulator, only one sideband is produced. d) In a balanced modulator, harmonics of the sidebands are suppressed. 80. In a balanced-ring modulator, the carrier suppression is accomplished by a) A dual-gate FET having symmetry b) Center-tapped transformers causing canceling magnetic fields c) The nonlinearity of the diodes that are used d) Symmetrical differential amplifier stages 81. Which cannot be used successfully to convert DSB-SC to SSB? a) Crystal filter b) Ceramic filter c) Mechanical filter d) Tank circuit 82. Another term for ripple amplitude for a ceramic filter is a) The shape factor b) The peak-to-valley ratio c) The insertion loss d) The quality factor 83. Which of the following is not an advantage of the phase method over the filter method in producing SSB? a) The design of the 90º phase-shift network for the intelligence frequencies is simple. b) Lower intelligence frequencies can be economically used, because a high-q filter is not necessary. c) Intermediate balanced modulators are not necessary, because high-q filters are not needed. d) It is easier to switch from one sideband to the other. 84. Once an SSB signal has been generated, it must be amplified Eduspace.co.in 17
by a) A nonlinear amplifier to conserve bandwidth b) A nonlinear amplifier to conserve energy c) A linear amplifier to conserve bandwidth d) A linear amplifier to avoid distortion 85. The advantages provided by carrier elimination in SSB do not apply to transmission of a) Code b) Music c) Noise 86. Provide the approximate "outside-of-passband" attenuation of a Butterworth filter. a) 3-dB slope per octave b) 3-dB slope per decade c) 6-dB slope per octave d) 6-dB slope per decade 87. An SSB receiver recreates the original intelligence signal by a) Mixing the USB with LSB signals and filtering out the resulting different frequencies b) Filtering out the difference between either sideband and the internally generated carrier signal c) Filtering out the harmonics of the received sideband signal frequencies d) Amplifying the dc term produced by mixing action 88. Common types of balanced modulators include a) Ring modulator b) Phase modulator c) Lattice modulator 89. Describe the oscilloscope waveform of an SSB transmitter's Eduspace.co.in 18
balanced modulator if it exhibits carrier leakthrough. a) Trapezoidal wave b) Sinewave c) FM wave d) AM wave 90. The two-tone test is used to a) Test carrier suppression b) Test filter ripple c) Test amplifier linearity d) None of the above FILL IN THE BLANK 91. The most obvious problem with SSB is accurate reinsertion at the receiver. a) audio b) modulator c) carrier d) compandor 92. Twin-sideband suppressed-carrier systems are often used in applications. a) industrial b) military c) amateur d) commercial 93. A balanced-ring modulator connects from diodes in a ring configuration. a) P-I-N b) Varicap c) point-contact d) matched 94. The balanced-ring modulator provides a output. Eduspace.co.in 19
a) suppressed b) DSB c) ISB d) VCO 95. The high-q filter in an SSB transmitter is used to eliminate a. a) sideband b) spur c) frequency d) harmonic 96. A filter offers the highest-possible Q for use in SSB transmitters. a) mechanical b) SAW c) crystal d) ceramic 97. The two common methods of generating SSB are the filter and methods. a) Butterworth b) Phase c) independent d) envelope 98. A balanced modulator used to recover the intelligence in an SSB signal is called a detector. a) Diode b) envelope c) product d) divisor 99. The BFO is a -frequency oscillator. a) backward Eduspace.co.in 20
b) balanced c) bandpass d) beat 100. A commonly used test to determine amplifier linearity is the test. a) two-tone b) tangential c) harmonic d) THD 101. Angle modulation includes the following types of modulation: a) FM b) PM c) AM e) a and b 102. The amount of frequency increase and decrease around the center frequency in an FM signal is called the a) Index of modulation b) Frequency deviation c) Phase deviation d) Bandwidth of the FM signal 103. The amount of frequency deviation is dependent on the intelligence frequency in a) An FM signal b) A PM signal c) Both FM and PM signals d) Neither FM nor PM signals 104. An FM signal has an intelligence frequency of 2 khz and a maximum deviation of 10 khz. If its carrier frequency is set at 162.4 Mhz, what is its index of modulation? a) 10 Eduspace.co.in 21
b) 5 c) 2 d) 20 105. The amount an FM carrier frequency deviates for a given modulating input voltage level is called the a) Frequency deviation b) Index of modulation c) Deviation constant d) Deviation ratio 106. Standard FM broadcast stations use a maximum bandwidth of a) 150 khz b) 200 khz c) 75 khz d) 15 khz 107. Carson's rule is used to approximate the necessary a) Frequency deviation b) Bandwidth c) Capture ratio d) Modulation index 108. An FM transmitter has an output power of 500 W when it is not modulated. When intelligence is added, its modulation index is 2.0. What is its output power with a modulation index of 2.0? a) 250 W b) 500 W c) 1000 W d) 2000 W 109. Another way to describe the modulation index is using the a) Deviation ratio b) Deviation constant Eduspace.co.in 22
c) Capture ratio d) Maximum deviation 110. The inherent ability of FM to minimize the effect of undesired signals operating at the same or nearly the same frequency as the desired station is known as the a) Capture effect b) Signal-to-noise ratio c) Noise figure d) Bessel function 111. In a Crosby FM transmitter, an FM signal having a center frequency of 2.04 Mhz and a deviation of 69 Hz is passed through four cascaded frequency multiplier stages: two triplers, one doubler, and one quadrupler. What type of signal appears at the output of the last multiplier stage? a) Center frequency of 2.04 Mhz and deviation of 4.96 khz b) Center frequency of 146.88 Mhz and deviation of 4.96 khz c) Center frequency of 2.04 Mhz and deviation of 69 Hz d) Center frequency of 146.88 Mhz and deviation of 69 Hz 112. The circuitry used to increase the operating frequency of a transmitter up to a specified value is called the a) Multiplier b) Expander c) Pump chain 113. The purpose of the matrix network in a stereo FM broadcast transmitter is to a) Mix the 38-kHz pilot carrier with the L R audio b) Convert the L and R channels to L + R and L R channels c) Separate the left channel from the right channel d) Modulate the L + R and L R signals with the carrier signal 114. An FM signal has an intelligence frequency of 5 khz and a Eduspace.co.in 23
maximum deviation of 25 khz. Its index of modulation is a) 125 b) 0.2 c) 5 d) 6 115. Frequency multipliers a) Are used to multiply the frequency of the carrier signal of an FM signal b) Consist of a class C amplifier followed by a tank circuit that filters out a single harmonic c) Are used to multiply the frequency deviation of an FM signal FILL IN THE BLANK 116. In FM receivers, the extracts the intelligence from a high-frequency carrier. a) discriminator b) multiplexer c) phase-detector d) matrix 117. Cross-modulation is similar to distortion. a) THD b) harmonic c) inter modulation d) noise 118. The difference between a receiver's maximum and minimum tolerable input signal is called its range. a) threshold b) useful c) working d) dynamic Eduspace.co.in 24
119. A is a circuit whose output is a constant amplitude for inputs above a critical value. a) clipper b) limiter c) compandor d) rail-to-rail 120. The discriminator is also called a. a) limiter b) oscillator c) detector d) mixer 121. The detector lends itself to integration on a single chip. a) ratio b) PLL c) quadrature d) slope 122. A PLL uses feedback to maintain a constant output frequency. a) Positive b) Negative c) audio d) AGC 123. A stereo demodulator contains a(n) -khz subcarrier. a) 19 b) 38 c) 15 d) 67 124. Wobbling the IF frequency can help determine if the limiter, discriminator, and circuits are operating correctly. Eduspace.co.in 25
a) mixer b) RF c) oscillator d) audio 125. The filter in a quadrature detector is usually a type. a) ceramic b) crystal c) Butterworth d) Hartley 126..A difference between AM and FM receiver block diagrams is that the FM version includes a a) Limiter b) Discriminator c) Deemphasis network 127. An FM receiver rarely works satisfactorily without an RF amplifier because a) FM receivers typically work with smaller input signal levels due to their noise characteristics. b) FM receivers have a narrower bandwidth. c) FM receivers do not have very much gain in their IF amplifier stages. d) FM receivers need RF amplifier stages to be able to decode stereo signals. 128. A certain FM receiver provides a voltage gain of 113 db prior to its limiter. The limiter's quieting voltage is 400 mv. Its sensitivity is approximately a) 2uV b) 1uV c) 0.9uV Eduspace.co.in 26
d) 0.7uV 129. The use of dual-gate MOSFETs in RF amplifier stages a) Offers increased dynamic range over those of JFETs b) Produces higher-frequency responses than do JFETs c) Produces higher values of voltage gain than do JFETs d) Is not compatible with AGC 130. The Foster-Seely detector design is superior to the ratio detector in that it a) Does not respond to any undesired amplitude variations b) Also provides an output AGC signal c) Offers superior linear response to wideband FM deviations d) Does not need a limiter stage 131. Local oscillator reradiation refers to radiation through the a) Receiver's wiring b) IF transformer c) Antenna 132. Which is not one of the three stages in which a PLL can be operated? a) Free-running b) Capture c) Locked/tracking d) Searching 133. A PLL is set up so that its VCO free-runs at 8.9 Mhz. The VCO does not change frequency unless its input is within +/-75 khz of 8.9 Mhz. After it does lock, the input frequency can be adjusted within +/-120 khz of 8.9 Mhz without having the PLL start to free-run again. The capture range of the PLL is a) 75 khz b) 120 khz Eduspace.co.in 27
c) 150 khz d) 240 khz 134. Slope detection is seldom used due to a) Nonlinearity b) Attenuation c) Complexity 135. In an FM stereo receiver, what is the purpose of the 23 53- khz filter? a) To filter out the SCA signal at the output of the discriminator b) To filter out the L R signal at the output of the discriminator c) To filter out the L + R signal at the output of the discriminator d) To produce separate L and R signals from the L + R and L signals 136. A dual audio amplifier is rated to provide 65 db of channel separation. If the right channel has 4 W of output power, how much of this power could be due to the left channel intelligence? a) 4 W b) 79 nw c) 1.26 uw d) 2.25 mw 137. The hold-in range for a PLL concerns the a) Range of frequencies in which it will remain locked b) Allowable range of dc voltage c) Allowable range of ac input voltage d) Satisfactory range of operating temperatures 138. The input signal into a PLL is at the a) VCO Eduspace.co.in 28
b) Low-pass filter c) Comparator d) Phase detector 139. The square-law relationship of the FETs input versus output a) Allows for greater sensitivity in an FM receiver b) Provides improved noise performance c) Reduces shot noise d) Minimizes cross-modulation 140. When troubleshooting a stereo demodulator, the input signal should be about a) 10uV rms b) 100uVrms c) 1 mv rms d) 100 mv rms 141. Why are image frequencies somewhat less of a problem in FM receivers than they are in SSB or AM receivers? a) SSB uses less bandwidth than does FM. b) FM signals have a capture effect characteristic. c) FM mixer stages are square-law devices. d) FM receivers do not use the super heterodyne design. 142. The tuned circuits prior to the mixer in a super heterodyne receiver are called the a) Front end b) Tuner c) Pre selector 143. The signal-strength meter that shows the relative signalstrength level is called the. a) S meter b) Signal meter Eduspace.co.in 29
c) Strength meter 144. An AM broadcast receiver has two identical tuned circuits with a Q of 50 prior to the IF stage. The IF frequency is 460 khz and the receiver is tuned to a station on 550 khz. The imagefrequency rejection is a) 41 db b) 36.2 db c) 72.4 db d) 82 db 145. An AGC that causes a step reduction in receiver gain at some arbitrarily high value of received signal in order to prevent overloading the receiver is known as a) Arbitrary AGC b) Auxiliary AGC c) Delayed AGC d) Variable AGC 146. Up-conversion offers the following advantage(s): a) Less expensive filters b) Good image-frequency rejection c) Minimized tuning range for the LO d) b and c 147. The range over which the input to a receiver or amplifier provides a usable output is called the a) Level of acceptability b) Dynamic range c) Degree of usefulness d) Specified input 148. A receiver has a 30-dB noise figure, a 1.5 Mhz bandwidth, a 6-dBm third intercept point, and a 3-dB signal-to-noise ratio. Its sensitivity is Eduspace.co.in 30
a) 94 db b) 82.2 db c) 79.2 db d) 81 db 149. Two-modulus dividers are used in the synthesis of frequencies into the VHF band due to a) Its ability to work at practical power consumptions b) Its ability to work at practical speeds c) The insufficient speed and power of the basic programmable divider designs 150. The disadvantage of direct digital synthesizers (DDS) over analog frequency synthesizers is a) Its complexity and cost b) Its limited maximum output frequency c) Its higher phase noise 151. The G.E. Phoenix radio is an example of a) An HF amateur transceiver using AM and SSB modulation modes b) A VHF commercial transceiver using the FM modulation mode and a channel guard function c) A military transceiver using all modes on HF frequencies d) A cellular telephone transceiver 152. The type of radio transmission that uses pseudorandomly switched frequency or time transmissions is known as a) Synthesizing b) Facsimile c) Spread spectrum d) Compression 153. The acronym CDMA refers to. Eduspace.co.in 31
a) Carrier-division multiple-access systems b) Capture-division multiple-access systems c) Code-division multiple-access systems d) Channel-division multiple-access systems 154. A typical problem encountered when troubleshooting a frequency synthesizer is a) A small frequency error b) A large frequency error c) No output 155. A transceiver is a) A transmitter that can be tuned to several bands of frequencies b) A transmitter that transmits digital data c) A receiver that receives digital data d) A transmitter and receiver in a single package 156. Communication equipment that includes a transmitter and receiver is commonly called a. a) transponder b) transceiver c) two-way d) preselector 157. Techniques for minimizing image frequencies include double conversion and -conversion. a) Down b) up c) crystal d) converter 158. Unwanted signals are often referred to as interference. a) Noise Eduspace.co.in 32
b) Selector c) squelch d) electromagnetic 159. The system cuts off a receiver's output during transmission lulls. a) squelch b) AGC c) quieting d) muting 160. The intercept is another name for the third-order intercept point. a) Noise b) Distortion c) input d) IM 161. The output of the PLL's phase comparator is called the voltage. a) error b) phase c) feedback d) correction 162. In DDS, the NCO contains the accumulator and ROM look-up table. a) Phase b) Frequency c) Error d) synthesis 163. Channel guard causes a very specific frequency to be encoded onto the carrier together with the intelligence. a) correction b) audio Eduspace.co.in 33
c) RF d) pseudorandom 164. Pseudorandom implies a sequence that can be but has the properties of randomness. a) decoded b) detected c) minimized d) recreated 165. The switch is responsible for switching the antenna between the transmitter and receiver in a transceiver. a) S b) guard c) TR d) hit Eduspace.co.in 34