3D153 Vol 1
.
- 1.
(001) What is one reason for modulation that involves modulating low frequency signals fortransmission over long distances?
- A.
Spectrum conservation.
- B.
Channel Allocation
- C.
Ease of Radiation
- D.
Companding.
Correct Answer
C. Ease of Radiation -
- 2.
(001) What are the three general categories used to produce modulation in radio frequency (RF)transmission today?
- A.
Binary amplitude shift keying, frequency shift keying, and phase shift keying.
- B.
Pulse amplitude, pulse width, and pulse position.
- C.
Amplitude, frequency, and phase.
- D.
Analog, digital and shift keying.
Correct Answer
C. Amplitude, frequency, and phase. -
- 3.
(002) If a carrier frequency of 1 MHz and a modulating tone of 10 kHz goes to the modulator, theoutput signal include
- A.
1.01 MHz, 1 MHz, and 0.99 MHz.
- B.
1.1 MHz, 1 MHz, and 0.9 MHz.
- C.
1.11 MHz, 1 MHz, 0.99 MHz.
- D.
1.111 MHz, 1 MHz, 0.999 MHz.
Correct Answer
A. 1.01 MHz, 1 MHz, and 0.99 MHz. -
- 4.
(002) The bandwidth of an amplitude modulated signal is
- A.
Two times the modulating signal
- B.
The same as the modulating signal.
- C.
Determined by the modulation index.
- D.
Defined in terms of maximum amount of modulation.
Correct Answer
A. Two times the modulating signal -
- 5.
(002) Use the formula on page 1–3. If an oscilloscope displays a modulation envelope having anEmax of 200 volts and an Emin of 20 volts, what is the modulation percentage?
- A.
81.8
- B.
85.5
- C.
88
- D.
122
Correct Answer
A. 81.8 -
- 6.
Which statement concerning bandwidth is true?
- A.
Overmodulating increases bandwidth because the distortion produces harmonics.
- B.
Undermodulating increases bandwidth because the distortion produces harmonics.
- C.
Overmodulating increases bandwidth because the output's increased amplitude.
- D.
Undermodulating increases bandwidth because the output's decreased amplitude.
Correct Answer
A. Overmodulating increases bandwidth because the distortion produces harmonics. -
- 7.
The output of the oscillator in a frequency modulation (FM) modulator increases infrequency with each
- A.
Positive half cycle of the carrier.
- B.
Negative half cycle of the carrier.
- C.
Positive half cycle of the modulating signal.
- D.
Negative half cycle of the modulating signal.
Correct Answer
A. Positive half cycle of the carrier. -
- 8.
In frequency modulation, a significant sideband contains at least what percentage of the totaltransmitted power?
- A.
1.
- B.
3.
- C.
10.
- D.
0.1.
Correct Answer
A. 1. -
- 9.
What is the formula to find the modulating index?
- A.
Deviation divided by frequency of modulation.
- B.
Deviation times frequency of modulation.
- C.
Sideband divide by carrier frequency.
- D.
Sideband times carrier frequency.
Correct Answer
A. Deviation divided by frequency of modulation. -
- 10.
A 5 kHz modulating signal has enough peak voltage to cause a deviation of 15 kHz. What isthe modulation index?
- A.
5
- B.
0.5
- C.
0.3
- D.
3
Correct Answer
D. 3 -
- 11.
What is it called when a narrow frequency band between adjacent stations preventfrequency modulated sidebands from overlapping?
- A.
Space.
- B.
Guard band.
- C.
Buffer zone.
- D.
Prevention field.
Correct Answer
B. Guard band. -
- 12.
In phase modulation, what part of the carrier signal is varied?
- A.
Frequency
- B.
Amplitude
- C.
Height
- D.
Phase
Correct Answer
D. Phase -
- 13.
In phase modulation, the carrier's
- A.
Phase is shifted at the rate of the modulating signal.
- B.
Phase shifted with the phase of the modulating signal.
- C.
Amplitude is shifted at the rate of the modulating signal.
- D.
amplitude is shifted with the phase of the modulating signal.
Correct Answer
A. Phase is shifted at the rate of the modulating signal. -
- 14.
What is the first step in the pulse code modulation process?
- A.
Discrete amplitudes are assigned to the sampling pulses.
- B.
A binary code number is assigned to the sample.
- C.
The quantizer limits the amplitude of the pulses.
- D.
The analog signal is band limited.
Correct Answer
D. The analog signal is band limited. -
- 15.
What part of the pulse code modulation process converts a continuous time signal into adiscrete time signal?
- A.
Sampling.
- B.
Rectifying
- C.
Oscillating
- D.
Band limiting
Correct Answer
A. Sampling. -
- 16.
In asynchronous transmissions, what bit is used by the receiving device to verify that thetransmission was received correctly?
- A.
Control
- B.
Parity
- C.
Start
- D.
Stop
Correct Answer
B. Parity -
- 17.
If an error should occur, what transmission is lost in an synchronous transmission?
- A.
One character.
- B.
Block of data.
- C.
A parity bit.
- D.
A stop bit.
Correct Answer
B. Block of data. -
- 18.
When using vertical redundancy check, what significance does the amount of ones have in adata bit pattern?
- A.
Determines parity.
- B.
Determines transmission rate.
- C.
Determines whether transmission is in ASCII format.
- D.
Determines whether transmission is synchronous or asynchronous.
Correct Answer
A. Determines parity. -
- 19.
What error detection method is used for checking a data block greater than 512 and is about99 percent effective in most applications?
- A.
Checksum.
- B.
Cyclic redundancy check
- C.
Vertical redundancy check.
- D.
Longitudinal redundancy check.
Correct Answer
B. Cyclic redundancy check -
- 20.
When using forward error control as a method of error correction, where does errorcorrection take place?
- A.
Receiving end.
- B.
In the oscillator.
- C.
Transmitting end.
- D.
In the primary buffers.
Correct Answer
A. Receiving end. -
- 21.
Light sources that are applicable to fiber optic waveguide are light-emitting diodes and
- A.
Photo transistors.
- B.
Hybrid photodiodes.
- C.
Semiconductor laser diodes.
- D.
Integrated photodiode/preamplifiers.
Correct Answer
C. Semiconductor laser diodes. -
- 22.
What type of light is emitted from a laser?
- A.
Incoherent.
- B.
Coherent.
- C.
Ordinary
- D.
Invisible
Correct Answer
B. Coherent. -
- 23.
What photo detector converts one photon to one electron?
- A.
Light emitting diode.
- B.
Avalanche photodiode.
- C.
Positive intrinsic negative diode.
- D.
Integrated photodiode/preamplifier.
Correct Answer
C. Positive intrinsic negative diode. -
- 24.
Which repeater amplifies optical signal without converting to and from the electricaldomain?
- A.
Receiver
- B.
Repeaters
- C.
Regenerators
- D.
Optical amplifiers
Correct Answer
D. Optical amplifiers -
- 25.
A short section of single fiber cable that has a connector at each end is called a
- A.
Pigtail.
- B.
Jumper
- C.
Patch cord
- D.
Breakout cables
Correct Answer
C. Patch cord -
- 26.
Which fiber-optic connector uses quick-release, keyed bayonet couplings that are preferredin situations where severe vibrations are not expected?
- A.
Biconic
- B.
Field (FC).
- C.
Straight tip (ST).
- D.
Sub-miniature, type A (SMA).
Correct Answer
C. Straight tip (ST). -
- 27.
High-altitude electromagnetic pulse is a wideband phenomenon that involves whichfrequency range?
- A.
1 hertz to 1 kilohertz.
- B.
1 hertz to 1 gigahertz.
- C.
10 hertz to 10 kilohertz.
- D.
10 hertz to 10 gigahertz.
Correct Answer
B. 1 hertz to 1 gigahertz. -
- 28.
High-altitude electromagnetic pulse environment protection is important for critical, timeurgent mission systems because it
- A.
Is a problem for electronic components in satellites and reentry vehicles.
- B.
Has a vertical amplitude that decreases inversely with distance, but remains significant for many kilometers.
- C.
Has very intense radial electrical fields, azimuthal magnetic fields, and time-varying air conductivity.
- D.
is the only nuclear environment that may be imposed on many systems simultaneously with the expenditure of very few weapons.
Correct Answer
D. is the only nuclear environment that may be imposed on many systems simultaneously with the expenditure of very few weapons. -
- 29.
A system-generated electromagnetic pulse is a problem for satellites and reentry vehiclesthat are
- A.
Susceptible to the wideband frequency phenomenon.
- B.
Directly exposed to nuclear radiations from a high-altitude burst.
- C.
Affected by the azimuthal magnetic fields and time-varying air conductivity.
- D.
Influenced by the signal fading or waveform distortion caused by the structured plasma field.
Correct Answer
B. Directly exposed to nuclear radiations from a high-altitude burst. -
- 30.
Which distinct region of the source region electromagnetic pulse is produced by theinteractions between the weapon products and the earth's atmosphere?
- A.
Secondary
- B.
Radiated
- C.
Plasma
- D.
Source
Correct Answer
D. Source -
- 31.
Atmospheric disturbances from initial nuclear radiation on higher frequencies affectcommunications by
- A.
Blackout effects.
- B.
Absorption effects.
- C.
Scintillation effects.
- D.
Attenuation effects.
Correct Answer
C. Scintillation effects. -
- 32.
Currents and voltages induced on power lines, cable links, and pipelines by electromagneticpulse are called
- A.
Scintillation.
- B.
Local effects
- C.
Source region
- D.
Long-line effects
Correct Answer
D. Long-line effects -
- 33.
Which type of filters are always used in combination with surge arresters?
- A.
Linear
- B.
AC Line
- C.
DC line
- D.
Power line
Correct Answer
A. Linear -
- 34.
If the interference can be eliminated by disconnecting the receiving antenna, the source ofthe disturbance is most likely
- A.
Line noise.
- B.
Internal to the radio.
- C.
External to the radio.
- D.
Radio receiver trouble.
Correct Answer
C. External to the radio. -
- 35.
Little or no variations in the strength of the interfering signal when moving the receivingantenna for short distance normally indicates
- A.
Enemy jamming.
- B.
Internal interference.
- C.
Radio receiver trouble.
- D.
Unintentional interference.
Correct Answer
A. Enemy jamming. -
- 36.
What type of electromagnetic interference occurs when a receiver responds to off-frequencysignals?
- A.
Rusty bolt.
- B.
Co-channel.
- C.
Brute force.
- D.
Spurious responses.
Correct Answer
D. Spurious responses. -
- 37.
Which type of intermodulation interference varies significantly with temperature andweather conditions?
- A.
Transmitter.
- B.
Rusty-bolt.
- C.
Spurious.
- D.
Receiver.
Correct Answer
B. Rusty-bolt. -
- 38.
What man-made noise results from voltage surges, arcing, or corona discharges?
- A.
Relays
- B.
Lighting
- C.
Power line
- D.
Switching equipment
Correct Answer
C. Power line -
- 39.
How can you normally eliminate electromagnetic interference noise bursts caused bysodium and mercury vapor lights that have stopped working while the power is still applied?
- A.
Change the bulb.
- B.
Ground out the light fixture.
- C.
Install a noise reject filter on the light.
- D.
Install a noise reject filter on the receiver.
Correct Answer
A. Change the bulb. -
- 40.
What Air Force program is used to resolve an electromagnetic interference incident?
- A.
Mishap prevention.
- B.
Frequency management.
- C.
Electrostatic discharge control.
- D.
Spectrum interference resolution.
Correct Answer
D. Spectrum interference resolution. -
- 41.
At what level does the Air Force want electromagnetic interference problems resolved?
- A.
Affected unit.
- B.
Affected major command.
- C.
Electromagnetic environmental effects office.
- D.
Spectrum interference resolution office.
Correct Answer
A. Affected unit. -
- 42.
What do you do when you are reasonably sure electromagnetic interference exists?
- A.
Request engineering assistance.
- B.
Contact the base frequency manager.
- C.
Systematically gather data for analysis.
- D.
Contact the spectrum interference resolution office.
Correct Answer
C. Systematically gather data for analysis. -
- 43.
Who is initially responsible for reporting an electromagnetic interference?
- A.
The operator.
- B.
Major command.
- C.
The frequency manager.
- D.
Federal Communications Commission.
Correct Answer
A. The operator. -
- 44.
Who is tasked to provide interference resolution support to the unified commanders?
- A.
The operator.
- B.
Joint spectrum center.
- C.
Installation spectrum manager.
- D.
Federal Communications Commission.
Correct Answer
B. Joint spectrum center. -
- 45.
Which part of the Fluke 8025A's display section indicates the absolute value of the input?
- A.
Digital.
- B.
Annunciator.
- C.
Range indicator.
- D.
Analog bar graph.
Correct Answer
D. Analog bar graph. -
- 46.
Which feature of the Fluke 8025A locks the measurement into the display for viewing andautomatically updates the display when you take a new measurement?
- A.
Rotary switch.
- B.
Range push button.
- C.
Power-up self-test.
- D.
Touch-hold push button.
Correct Answer
D. Touch-hold push button. -
- 47.
When you use the Fluke 8025A, which voltage range do you select to measure 50 volts DC?
- A.
Volts AC
- B.
Volts DC
- C.
Millivolts AC.
- D.
Millivolts DC.
Correct Answer
B. Volts DC -
- 48.
How are voltage, time, and depth represented on the oscilloscope display?
- A.
Voltage = intensity, time = vertical axis, and depth = horizontal axis.
- B.
Voltage = intensity, time = horizontal axis, and depth = vertical axis.
- C.
Voltage = horizontal axis, time = vertical axis, and depth = intensity.
- D.
Voltage = vertical axis, time = horizontal axis, and depth = intensity.
Correct Answer
D. Voltage = vertical axis, time = horizontal axis, and depth = intensity. -
- 49.
Which oscilloscope's input coupling position allows you to view both AC and DCcomponents of the input signal?
- A.
DC
- B.
AC
- C.
Norm
- D.
Ground
Correct Answer
A. DC -
- 50.
Which oscilloscope probe is essentially just a shielded piece of wire?
- A.
Current.
- B.
Passive 1:1.
- C.
Passive divider, 1:10.
- D.
Active field effect transistor.
Correct Answer
B. Passive 1:1. -
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