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EST
  • 1. The theory of radio waves was iriginated by?
A) None of these
B) Hertz
C) Marconi
D) Bell
E) Maxwell
  • 2. The bandwidth required for a modulated carrier depends on:
A) the signal-plus-noise to noise ratio
B) None of these
C) the baseband frequency range
D) the signal-to-noise ratio
E) the carrier frequency
  • 3. When two or more signals share a common channel, it is called:
A) SINAD
B) sub-channeling
C) multiplexing
D) None of these
E) signal switching
  • 4. Distortion is caused by:
A) baseband frequencies "mixing" with each other
B) baseband frequencies "mixing" with each other
C) creation of harmonics of baseband frequencies
D) All of the above
E) None of these
  • 5. The baseband bandwidth for a voice-grade (telephone) signal is:
A) approximately 3 kHz
B) All of the above
C) at least 5 kHz
D) 20 Hz to 15,000 Hz
E) None of these
  • 6. The power density of "flicker" noise is:
A) greater at low frequencies
B) the same at all frequencies
C) greater at high frequencies
D) the same as "white" noise
E) None of these
  • 7. When two noise voltages, V1 and V2, are combined, the total voltage VT is:
A) VT = (V1 + V2)/2
B) VT = sqrt(V1 × V2)
C) None of these
D) VT = sqrt(V1 × V1 + V2 × V2)
E) VT = sqrt(V1 × V2)
  • 8. Signal-to-Noise ratio is calculated as:
A) All of the above
B) signal voltage divided by noise voltage
C) None of these
D) first add the signal power to the noise power, then divide by noise power
E) signal power divided by noise power
  • 9. Noise Figure is a measure of:
A) how much noise is in a communications system
B) how much noise is in the channel
C) None of these
D) signal-to-noise ratio in dB
E) how much noise an amplifier adds to a signal
  • 10. SINAD is calculated as:
A) signal power divided by noise power
B) All of the above
C) signal voltage divided by noise voltage
D) None of these
E) first add the signal power to the noise power, then divide by noise power
  • 11. The UHF band starts at ____________________ MHz.
A) 300
B) None of these
C) 500
D) 400
E) 200
  • 12. The VHF band starts at ____________________ MHz.
A) 30
B) None of these
C) 50
D) 60
E) 40
  • 13. The equipment used to show signals in the frequency domain is the _________________________.
A) spectrum domain monitor
B) spectrum displayer
C) spectrum signal monitor
D) None of these
E) spectrum analyzer
  • 14. Suppose there is 30 μV from one noise source that is combined with 40 μV from another noise source.Calculate the total noise voltage.
A) 50 μV
B) 30 μV
C) 40 μV
D) None of these
E) 60 μV
  • 15. If you have 100 mV of signal and 10 mV of noise, both across the same 100-ohm load, what is the signal-to-noise ratio in dB?
A) 20 dB
B) None of these
C) 50 dB
D) 30 dB
E) 40 dB
  • 16. A microwave receiver has a noise temperature of 145 K. Find its noise figure.
A) 0.5
B) 2.5
C) None of these
D) 1.5
E) 1
  • 17. The "Miller Effect" can:
A) cause an amplifier to oscillate
B) reduce the bandwidth of an amplifier
C) All of the above
D) cause an amplifier to lose gain
E) None of these
  • 18. The Miller Effect can be avoided by:
A) None of these
B) using a common-base amplifier
C) it cannot be avoided
D) using a common-emitter amplifier
E) increasing the Q of the tuned circuit
  • 19. For a "frequency multiplier" to work, it requires:
A) a nonlinear circuit
B) a signal containing harmonics
C) a linear amplifier
D) None of these
E) an input signal that is an integer multiple of the desired frequency
  • 20. The conditions for sinusoidal oscillation from an amplifier are called:
A) the Bode criteria
B) the Barkhausen criteria
C) the Hartley criteria
D) None of these
E) the loop-gain criteria
  • 21. Generally, conductor lengths in RF circuits should be
A) slow
B) None of these
C) fast
D) long
E) short
  • 22. At UHF frequencies and above, elements must be considered as ____________________ instead of as being "lumped".
A) dispersed
B) connected
C) None of these
D) distributed
E) combined
  • 23. A ____________________ circuit is used to remove RF from the DC voltage bus.
A) recoupling
B) None of these
C) uncoupling
D) coupling
E) decoupling
  • 24. What inductance would you use with a 47-pF capacitor to make a tuned circuit for 10 MHz?
A) 6.4 μH
B) None of these
C) 5.4 μH
D) 6.2 μH
E) 9.2 μH
  • 25. What value of Q is required for a 10-MHz tuned circuit to have a bandwidth of 100 kHz?
A) 10
B) 500
C) 100
D) of None these
E) 1000
  • 26. A tuned-circuit amplifier with a gain of 10 is being used to make an oscillator. What should be the value of the feedback ratio to satisfy the Barkhausen criteria?
A) None of these
B) 0.2
C) 0.1
D) 0.3
E) 0.5
  • 27. If a varactor has a capacitance of 90 pF at zero volts, what will be the capacitance at 4 volts?
A) 30 pF
B) 28 pF
C) 40 pF
D) 53 pF
E) None of these
  • 28. AM stands for:
A) Angle Modulation
B) Antenna Modulation
C) Audio Modulation
D) None of these
E) Amplitude Modulation
  • 29. The "envelope" of an AM signal is due to:
A) the baseband signal
B) None of these
C) All of the above
D) the carrier signal
E) the amplitude signal
  • 30. If an AM radio station increases its modulation index, you would expect:
A) the audio to get louder at the receiver
B) the signal-to-noise ratio to increase
C) None of these
D) All of the above
E) the received RF signal to increase
  • 31. As compared to plain AM, SSB AM:
A) requires less bandwidth
B) requires a more complex demodulator circuit
C) All of the above
D) is more efficient
E) None of these
  • 32. The SC in SSB SC stands for:
A) sideband-carrier
B) suppressed-carrier
C) self-carrier
D) None of these
E) single-carrier
  • 33. The FM modulation index:
A) increases with both deviation and modulation frequency
B) increases with deviation and decreases with modulation frequency
C) is equal to twice the deviation
D) decreases with deviation and increases with modulation frequency
E) None of these
  • 34. The bandwidth of an FM signal is considered to be limited because:
A) None of these
B) it is equal to the frequency deviation
C) it is band-limited at the receiver
D) the power in the outer sidebands is negligible
E) there can only be a finite number of sidebands
  • 35. What is the relative amplitude of the third pair of sidebands of an FM signal with m = 6
A) 0.11
B) 0.5
C) None of these
D) 0.2
E) 0.3
  • 36. A 200 kHz carrier is modulated by a 2.5kHz signal. The fourth pair of sidebands are spaced from the carrier by
A) 13 kHz
B) 10 kHz
C) None of these
D) 11 kHz
E) 12 kHz
  • 37. An FM transmitter has a maximum deviation of 12 kHz and a maximum modulating frequency of 12 kHz. The bandwidth by Carson’s rule is
A) 68 kHz
B) 20 kHz
C) 48 kHz
D) None of these
E) 50 kHz
  • 38. The maximum allowed deviation of the FM sound signal in TV is 25 kHz. If the actual deviation is 18 kHz, the percent modulation is
A) 50%
B) 72%
C) None of these
D) 100%
E) 80%
  • 39. The frequency change of a crystal oscillator produced by a varactor diode is
A) fast
B) None of these
C) small
D) slow
E) large
  • 40. Frequency modulation transmitters are more efficient because their power is increased by what type of amplifier
A) None of these
B) class B
C) class C
D) class D
E) class A
  • 41. A reactance modulator looks like a capacitance of 35 pF in parallel with the oscillator-tuned circuit whose inductance is 50 μH and capacitance is 40 pF. What is the center frequency of the oscillator prior to FM?
A) 152 MHz
B) 29 MHz
C) 206 MHz
D) 100 MHz
E) None of these
  • 42. The input to a PLL is 2 MHz. In order for the PLL to be locked, the VCO output must be
A) 4 MHz
B) 8 MHz
C) 2 MHz
D) None of these
E) 16 MHz
  • 43. A class B amplifier conducts for how many degrees of an input sine wave?
A) 75 degrees
B) 90 degrees
C) 180 degrees
D) 360 degrees
E) None of these
  • 44. An FM transmitter has a 9 MHz crystal carrier oscillator and frequency multipliers of 2, 3, 4. The output frequency is
A) 220 MHz
B) 216 MHz
C) 300 MHz
D) None of these
E) 119 MHz
  • 45. A tuned circuit resonates at 12 MHz with an inductance of 5 μH whose resistance is 6 Ω. The circuit bandwidth is
A) 40 kHz
B) 61 kHz
C) 250 kHz
D) 191 kHz
E) None of these
  • 46. The maximum bandwidth that an analog signal use with a sampling frequency of 108 kHz is
A) 54 kHz
B) 70 kHz
C) None of these
D) 70 kHz
E) 150 kHz
  • 47. Transmitting data as serial binary words is called
A) T-1
B) None of these
C) PAM
D) CODEC
E) PCM
  • 48. Sampling an analog signal produces
A) T-1
B) None of these
C) TCM
D) CODEC
E) PAM
  • 49. Which of the following is not a common transmission line impedance?
A) 75 Ω
B) None of these
C) 10 Ω
D) 120 Ω
E) 100 Ω
  • 50. The desirable SWR on a transmission line is
A) None of these
B) 1
C) 2
D) 0
E) 5
  • 51. A 50Ω coax is connected to a 73Ω antenna. The SWR is
A) 1.5
B) None of these
C) 3.8
D) 2.5
E) 1.46
  • 52. The impedance of a dipole is about
A) 28 Ω
B) None of these
C) 50 Ω
D) 50 Ω
E) 73 Ω
  • 53. An antenna has a power gain of 15. The power applied to the antenna is 32 W. The effective radiated power is
A) 480 W
B) None of these
C) 250 W
D) 372 W
E) 483 W
  • 54. A rectangular waveguide has a width of 1 in. and a height of 0.6 in. Its cutoff frequency is
A) 10 GHz
B) None of these
C) 25 GHz
D) 1.2GHz
E) 5.9 GHz
  • 55. Which diode is a popular microwave oscillator
A) Yagi
B) Gunn
C) Radar
D) Tunnel
E) None of these
  • 56. Most satellites operate in which frequency band?
A) 4 GHz to 30 GHz
B) None of these
C) 3 GHz to 30 GHz
D) 6 GHz to 30 GHz
E) 5 GHz to 30 GHz
  • 57. The main power sources for a satellite are
A) Solar cells
B) Battery pack
C) None of these
D) UV rays
E) Electricity
  • 58. A common up-converter and down-converter IF is
A) None of these
B) 60 MHz
C) 50 MHz
D) 80 MHz
E) 70 MHz
  • 59. The most widely used data communications code is
A) DECIMAL
B) BINARY
C) ASCII
D) None of these
E) FREQUENCY
  • 60. The ASCII code has
A) 8 bits
B) 9 bits
C) None of these
D) 10 bits
E) 7 bits
  • 61. The typical bandwidth of a satellite band is
A) 500 MHz
B) 100 MHz
C) 750 MHz
D) 1000 MHz
E) None of these
  • 62. The modulation normally used with digital data is
A) DPSK
B) None of these
C) QWERTY
D) QPSK
E) CODEC
  • 63. The main circuit in a PSN generator is a(n)
A) NOR
B) OR
C) AND
D) XOR
E) None of these
  • 64. Which cable length has the highest attenuation?
A) 2 KM
B) 70 M
C) None of these
D) 1 KM
E) 5 M
  • 65. The core of a fiber-optic cable is surrounded by
A) None of these
B) Twisted wires
C) Cladding
D) Fiber glass
E) Rubber
  • 66. The wavelength of visible light extends from
A) 150 to 750 nm
B) None of these
C) 400 to 750 nm
D) 500 to 750 nm
E) 200 to 750 nm
  • 67. Both LEDs and ILDs operate correctly with
A) All of the above
B) None of these
C) Forward bias
D) Backward bias
E) Side bias
  • 68. Fiber-optic with attenuations of 1.8, 3.4, 5.9 and 18 dB are linked together. The total loss is
A) 5.57 dB
B) 4.71 dB
C) 29.1 dB
D) None of these
E) 10 dB
  • 69. The speed of light is
A) None of these
B) 300,000,000 m/s
C) 200,000,000 m/s
D) 1,000,000 m/s
E) 100,000,000 m/s
  • 70. In ______ schemes, the voltages are on the both sides of the time axis. For example, the voltage level for 0 can be positive and the voltage level for 1 can be negative.In ______ schemes, the voltages are on the both sides of the time axis. For example, the voltage level for 0 can be positive and the voltage level for 1 can be negative.
A) None of these
B) polar
C) All of the above
D) unipolar
E) bipolar
  • 71. ______ substitutes eight consecutive zeros with 000VB0VB.
A) HDB3
B) B8ZS
C) All of the above
D) B4B8
E) None of these
  • 72. ________ provides synchronization without increasing the number of bits.
A) ________ provides synchronization without increasing the number of bits.
B) None of these
C) All of the above
D) Block coding
E) Line coding
  • 73. In Manchester and differential Manchester encoding, the transition at the middle of the bit is used for __________.
A) bit transfer
B) baud transfer
C) All of the above
D) None of these
E) synchronization
  • 74. PCM is an example of _______ conversion.
A) analog-to-digital
B) digital-to-analog
C) None of these
D) digital-to-digital
E) analog-to-analog
  • 75. The data rate is sometimes called the ___ rate.
A) None of these
B) signal
C) bit
D) All of the above
E) baud
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