CDC 3d153 volume 2 v2 (april 2013)
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CDC 3D153 01 1206, Edit Code 02 (April 2013) Volume 2 Units 1-5 Unit 1: Antenna Theory Unit 2: Electromagnetic Wave Theory Unit 3: Transmission Security Techniques, Data Linking Concepts and Jam-Resistant Communications Unit 4: Other RF Transmission Systems Unit 5: High Frequency Communications
- 1.Equipment used for generating, amplifying, and transmitting RF carrier is collectively called
- A.
A receiver.
- B.
An antenna.
- C.
A transmitter.
- D.
A transmission line.
- 2.What basic receiver function involves having the transmitted electromagnetic wave pass through the receive antenna in such a manner as to induce a voltage in the antenna?
- A.
Reproduction.
- B.
Reception.
- C.
Detection.
- D.
Selection.
- 3.The ability of a receiver to reproduce the signal of a very weak station is the characteristic of the receiver’s
- A.
Fidelity.
- B.
Capacity.
- C.
Sensitivity.
- D.
Selectivity.
- 4.The ability to reproduce the input signal accurately is the characteristics of the receiver’s
- A.
Fidelity.
- B.
Capacity.
- C.
Sensitivity.
- D.
Selectivity.
- 5.Which of the following CANNOT be performed by the transceiver’s computerized components and micro-circuitry?
- A.
Specific equipment faults.
- B.
Internal equipment tests.
- C.
Internal calibrations.
- D.
Repair itself.
- 6.Resistance of the conductor material in a transmission line leads to which type of loss?
- A.
Copper.
- B.
Radiation.
- C.
Inductive.
- D.
Skin-effect.
- 7.Leakage loss in a transmission line can be minimized by using a
- A.
Thinner conductor.
- B.
Thicker conductor.
- C.
Very low-resistance dielectric.
- D.
Very high-resistance dielectric.
- 8.A transmission line that consists of a center conductor placed inside a rigid metal tube functioning as the outer tube is called a
- A.
Flexible coaxial cable.
- B.
Rigid coaxial cable.
- C.
Waveguide.
- D.
Twin lead.
- 9.Which statement concerning waveguides is FALSE?
- A.
Very slight damage to the external surface of a waveguide can cause arcing.
- B.
Their conductive material construction is easily dented.
- C.
Effectiveness of waveguides is hindered by moisture.
- D.
Waveguides can be destroyed by corrosion.
- 10.What two properties of a transmission line determine its characteristic impedance?
- A.
Inductance and resistance.
- B.
Inductance and capacitance.
- C.
Resistance and capacitance.
- D.
Length and type of shielding.
- 11.Using figure 1–10, determine the electrical length if the frequency is changed from 150 MHz to 250 MHz.
- A.
8.33 meters.
- B.
8.33 wavelengths.
- C.
83.3 meters.
- D.
83.3 wavelengths.
- 12.Which statement concerning line lengths is TRUE?
- A.
Frequency and electrical length are inversely proportional.
- B.
Frequency and physical length are directly proportional.
- C.
With constant physical length, frequency and electrical length are directly related.
- D.
With constant physical length, frequency and electrical length are inversely related.
- 13.A nonresonant transmission line is a line
- A.
Having reflected waves.
- B.
Having no reflected waves.
- C.
With maximum voltage across its open termination.
- D.
With maximum voltage across its shorted termination.
- 14.If a transmission line is terminated in an open, what will likely result?
- A.
Signal loss would be negligible.
- B.
There would be significant signal loss.
- C.
Current would be at maximum at the termination.
- D.
Voltage would be at minimum at the termination.
- 15.The concept that alternating current changes in magnitude and reverses its direction during each cycle is
- A.
An unproven hypothesis.
- B.
The definition of propagation.
- C.
What makes radio transmission possible.
- D.
What led to the discovery of direct current.
- 16.At what point do magnetic fields around a wire no longer have time to collapse completely between alternations?
- A.
60 cycles per second (cps).
- B.
120 cps.
- C.
10,000 cps.
- D.
15,000 cps.
- 17.Which basic field detaches from the antenna and travels through space at great distances?
- A.
Radiation.
- B.
Induction.
- C.
Gravitational.
- D.
Electromotive.
- 18.Areas in which no antenna radiation pattern passes through are called
- A.
Nulls.
- B.
Lobes.
- C.
Free space.
- D.
Nonresonant.
- 19.If the electric field component travels in a plane perpendicular to the Earth’s surface, the radio wave is considered to be polarized
- A.
Magnetically.
- B.
Horizontally.
- C.
Circularly.
- D.
Vertically.
- 20.The actual range of frequencies within the antenna’s bandwidth is called the
- A.
Wavelength.
- B.
Operating zone.
- C.
Frequency range.
- D.
Bandwidth range.
- 21.What measurement is used to determine whether an antenna is resonant at a particular frequency?
- A.
Distortion.
- B.
Standing wave ratio.
- C.
Signal-to-noise ratio.
- D.
Percent of modulation.
- 22.The ability of an antenna to both receive and transmit equally well is known as the antenna’s
- A.
Bandwidth.
- B.
Resonance.
- C.
Reciprocity.
- D.
Effectiveness.
- 23.The standard used to measure the radiating effectiveness (gain) of an antenna system is the
- A.
Marconi antenna.
- B.
Isotropic antenna.
- C.
Hertz antenna.
- D.
Whip antenna.
- 24.What does the overall effectiveness of an entire transmitting and receiving system depend largely upon?
- A.
Impedance matching.
- B.
Antenna distance.
- C.
Antenna properties.
- D.
Line characteristics.
- 25.Which antenna radiates radio energy equally well in all directions?
- A.
Omni-directional.
- B.
Uni-directional.
- C.
Bi-directional.
- D.
Directional.
- 26.Which antenna type is usually used on long-range, point-to-point communication where the concentrated radio energy is needed for circuit reliability?
- A.
Omni-directional.
- B.
Uni-directional.
- C.
Bi-directional.
- D.
Circular.
- 27.Ungrounded lengths of wire specifically designed to be either a half-wavelength or more than full wavelength long is called a
- A.
Reflector.
- B.
Hertz antenna.
- C.
Marconi antenna.
- D.
Vertical monopole.
- 28.A dipole or long-wire antenna is an example of a
- A.
Whip antenna.
- B.
Hertz antenna.
- C.
Marconi antenna.
- D.
Vertical monopole.
- 29.What type of directivity does the whip antenna provide?
- A.
Bidirectional.
- B.
Unidirectional.
- C.
Omni-directional.
- D.
Near vertical directional.
- 30.What is probably the worst antenna that can be used on sky-wave circuits?
- A.
Whip.
- B.
Dipole.
- C.
Rhombic.
- D.
Discone.
- 31.What antenna radiates or receives on many of its particular elements?
- A.
Whip.
- B.
Dipole.
- C.
Discone.
- D.
Log-periodic.
- 32.What is the minimum length for a long-wire antenna?
- A.
One-quarter wavelength.
- B.
One-half wavelength.
- C.
One wavelength.
- D.
Two wavelengths.
- 33.A long-wire’s takeoff angle depends on the antenna’s
- A.
Length.
- B.
Directivity.
- C.
Front-to-back ratio.
- D.
Standing wave ratio.
- 34.A common satellite antenna is the
- A.
Whip.
- B.
Discone.
- C.
Parabolic.
- D.
Long-wire.
- 35.A helical satellite antenna radiates a signal with what type of polarization?
- A.
Horizontal.
- B.
Vertical.
- C.
Circular.
- D.
Linear.
- 36.Which type of airborne antenna can be designed into any part of an aerospace vehicle’s surface, so that it does not upset its aerodynamic properties?
- A.
Fixed blade.
- B.
Conformal.
- C.
Probe tip.
- D.
Whip.
- 37.In selecting an antenna for a circuit, what is the first thing to consider?
- A.
Type of propagation.
- B.
Type of antenna.
- C.
Distance of the communication.
- D.
Operating frequency of the antenna.
- 38.In HF communications, by replacing the vertical antenna with a dipole antenna that’s a quarter wavelength off the ground, what are you able to get from your antenna transmission?
- A.
Higher take-off angle.
- B.
Increase efficiency.
- C.
Better reciprocity.
- D.
Twice the gain.
- 39.In siting a radio station, which foliage would have more of an adverse effect on radio wave propagation?
- A.
Broadleaf trees.
- B.
Evergreen trees.
- C.
Swamp grass.
- D.
Sagebrush.
- 40.What has the greatest effect on an antenna?
- A.
The sun.
- B.
The earth.
- C.
The operator.
- D.
The ionosphere.
- 41.Which environment would be considered the most challenging for an RF transmission systems technician to establish and operate a radio station from?
- A.
Amazon.
- B.
North Pole.
- C.
Sahara Desert.
- D.
Sierra Nevada Mountains.
- 42.Radio sets are left on 24-hours a day in a jungle environment to
- A.
Combat fungus.
- B.
Keep insects away.
- C.
Prevent short circuits.
- D.
Maintain frequency stability.
- 43.Which environment area will increase maintenance problems with dust and sand?
- A.
Polar.
- B.
Jungle.
- C.
Desert.
- D.
Mountainous.
- 44.In mountainous terrain, with a mountain between you and the distant end, which of these antennas is more effective?
- A.
Whip.
- B.
Dipole.
- C.
Discone.
- D.
Near-vertical incidence skywave.
- 45.Radio waves that travel near the earth’s surface are called
- A.
Earth waves.
- B.
Global waves.
- C.
Ground waves.
- D.
Terrestrial waves.
- 46.The earth’s conductivity is determined by the type of
- A.
Air and moisture content in the propagation path.
- B.
Antenna being used at the time of transmission.
- C.
Soil and water in the propagation path.
- D.
Soil and air in the propagation path.
- 47.Sky wave transmission is used for which type of communications?
- A.
Long distance.
- B.
Subterrestrial.
- C.
Atmospheric.
- D.
Line of sight.
- 48.The angle at which a radio wave enters the ionosphere is known as the
- A.
Skip angle.
- B.
Critical angle.
- C.
Angle of entrance.
- D.
Angle of incidence.
- 49.Radio waves that angled too low are
- A.
Absorbed.
- B.
Refracted.
- C.
Returned to earth.
- D.
Passed into space.
- 50.In HF communications, the lowest frequency that arrives at the distant receiver on 90 percent of the undisturbed days of the month is called the
- A.
Maximum usable frequency.
- B.
Lowest usable frequency.
- C.
Operating frequency.
- D.
Critical frequency.
- 51.Magneton splitting creates two waves called
- A.
Direct and indirect.
- B.
Ordinary and abnormal.
- C.
In-phase and out-of-phase.
- D.
Ordinary and extraordinary.
- 52.In dealing with sky/ground wave propagation, the area of silence where no signals are received is known as the
- A.
Propagation distance.
- B.
Skip distance.
- C.
Dead zone.
- D.
Skip zone.
- 53.How many regions make up the atmosphere?
- A.
2
- B.
3
- C.
4
- D.
5
- 54.Scientist call the ionosphere an extension of the
- A.
Thermosphere.
- B.
Stratosphere.
- C.
Mesosphere.
- D.
Exosphere.
- 55.What occurs when high-energy ultraviolet light waves from the sun enter the ionospheric region of the atmosphere and strike the gas atoms?
- A.
Ionization.
- B.
Modulation.
- C.
Conductivity.
- D.
Recombination.
- 56.Sunspots are disturbances
- A.
In the sun’s atmosphere.
- B.
On the sun’s surface.
- C.
In the ionosphere.
- D.
Beneath the sun’s surface.
- 57.Sunspots occur on an
- A.
11-day cycle.
- B.
11-week cycle.
- C.
11-month cycle.
- D.
11-year cycle.
- 58.What U.S. government agency divides the radio frequency spectrum into different bands?
- A.
Federal Aviation Agency.
- B.
American National Standard Institute.
- C.
Federal Communications Commission.
- D.
Institute of Electrical & Electronics Engineers, Inc.
- 59.Near-vertical-incidence sky wave operations are most effective when you’re using
- A.
Lower high frequency (HF) range.
- B.
Higher (HF) range.
- C.
Medium HF range.
- D.
Low takeoff antenna angles.
- 60.Which frequency band is most susceptible to jamming?
- A.
Low frequency.
- B.
Medium frequency.
- C.
High frequency.
- D.
Very high frequency.
- 61.What frequency bands does the MILSTAR satellite system uses?
- A.
High frequency (HF) and ultra high frequency (UHF).
- B.
Super high frequency (SHF) and extremely high frequency (EHF).
- C.
Very high frequency (VHF) and SHF.
- D.
VHF and UHF.
- 62.The main very high frequency/ultra high frequency communications emphasis is on
- A.
Long range deployable communications.
- B.
Short range fixed communications.
- C.
Emergency communications.
- D.
Air-ground communications.
- 63.What is the primary transmission path for frequencies in the super high/extremely high frequency range?
- A.
Direct.
- B.
Ground.
- C.
Surface.
- D.
Sky wave.
- 64.Super high/extremely high frequency range is limited to
- A.
Scattering.
- B.
Line-of-sight.
- C.
Earth’s conductivity.
- D.
Atmospheric absorption.
- 65.The refractive index of air depends on moisture,
- A.
Atmospheric pressure, and temperature.
- B.
Atmospheric pressure, and frequency.
- C.
Receive signal level, and temperature.
- D.
Receive signal level, and frequency.
- 66.When comparing the radio and optical horizons, which one is farther away and by what percent?
- A.
Optical; 15.
- B.
Radio; 15.
- C.
Optical; 33.
- D.
Radio; 33.
- 67.What permits communication in shadow regions behind obstacles?
- A.
Reflection.
- B.
Scattering.
- C.
Refraction.
- D.
Diffraction.
- 68.What frequency range will show little effect from precipitation?
- A.
High frequency.
- B.
Ultra-high frequency.
- C.
Super-high frequency.
- D.
Extremely-high frequency.
- 69.Line of sight radio waves that are guided through the air between two layers of the atmosphere are known as
- A.
Channeling.
- B.
Guiding.
- C.
Ducting.
- D.
Piping.
- 70.Examples of electronic protection includes all of the following EXCEPT
- A.
Frequency agility in a radio.
- B.
Communications intelligence.
- C.
Electronic and material shielding for systems.
- D.
Process to counter meaconing, interference, jamming, and intrusion.
- 71.Which electronic warfare component responds to taskings to search for, intercept, identify, and locate intentional and unintentional sources of radiated energy?
- A.
Attack.
- B.
Control.
- C.
Support.
- D.
Protection.
- 72.What is the first step in electronic warfare application?
- A.
Denial.
- B.
Detection.
- C.
Deception.
- D.
Disruption.
- 73.Name the process of unscrambling the encrypted information so that it is intelligible.
- A.
Decryption.
- B.
Encryption.
- C.
Cryptography.
- D.
Cryptanalysis.
- 74.How many selectable traffic key slots does the KG–84A have?
- A.
1.
- B.
2.
- C.
4.
- D.
8.
- 75.Which switch on the KY–57 VINSON zeroizes channels one through five?
- A.
Fill.
- B.
Mode.
- C.
Power.
- D.
Volume.
- 76.The common name for the method of changing the encryption keys over the radio channel in a two-way radio system is called
- A.
Over-the-air-rekeying.
- B.
Asymmetric.
- C.
Symmetric.
- D.
Off-line.
- 77.In frequency hopping operation, the interval at which each transmitter remains on a given frequency for a specific time is known as
- A.
Dwell time.
- B.
Hopping rate.
- C.
Frequency offset.
- D.
Transmitter velocity.
- 78.From what source does the RT–1523 SINCGARS radio’s control module obtain instructions during remote and local operation respectively?
- A.
Keyboard interface and front panel.
- B.
Remote I/O module and front panel.
- C.
Keyboard interface and local I/O module.
- D.
Remote I/O module and keyboard assembly.
- 79.Concerning HAVE QUICK II communications multiple word-of-day (MWOD), how long can each word-of-day (WOD) be used?
- A.
Each is used until it is manually changed.
- B.
For a total of three days.
- C.
For 48 hours.
- D.
For 24 hours.
- 80.Which statement is NOT a characteristic of the AN/GRC–171B(V)4 transceiver?
- A.
It operates from 116 MHz to 149.975 MHz.
- B.
It provides antijam communications in AM and FM.
- C.
It contains both HAVE QUICK and HAVE QUICK II.
- D.
It can communicate on any one of 7,000 available channels.
- 81.What identifies the output power of the AN/GRC–171B(V)4 transceiver?
- A.
25 watts in both AM and FM.
- B.
20 watts in AM and 50 watts in FM.
- C.
20 watts in AM and 20 watts in FM.
- D.
50 watts in narrowband and 25 watts in wideband.
- 82.What commonly referred link is the joint tactical information distribution system?
- A.
4A.
- B.
11.
- C.
16.
- D.
22.
- 83.Which multiple channel access method eliminates the requirement for a net control station in the joint tactical information distribution system?
- A.
Code division.
- B.
Time division.
- C.
Space division.
- D.
Frequency division.
- 84.What type of network radio does the Air Force use for close air support?
- A.
Single channel ground and airborne radio system.
- B.
Enhanced position location reporting system.
- C.
Joint tactical information distribution system.
- D.
Situation awareness data link.
- 85.The family of radios that are scaled for use in all domains, will function with programmable waveforms, and be based on a common core architecture is the
- A.
Joint tactical information distribution system.
- B.
Single channel ground and airborne radio.
- C.
Multiband radio sets.
- D.
Joint tactical radio.
- 86.How many programmable devices can the multi-band inter/intra team radio hold?
- A.
3.
- B.
5.
- C.
7.
- D.
10.
- 87.Which conventional land mobile radio device serves as the hub of a net?
- A.
Portable.
- B.
Mobile.
- C.
Repeater.
- D.
Base station.
- 88.How many talkgroups can a trunked mobile radio monitor at one time?
- A.
1.
- B.
2.
- C.
3.
- D.
All the talkgroups programmed into the radio.
- 89.Who has the ability to patch different talkgroups together?
- A.
Control station.
- B.
Dispatch console.
- C.
Portable.
- D.
Mobile.
- 90.What Air Force instruction (AFI) requires communications squadrons to maintain “installation warning systems”?
- A.
AFI 10–2501.
- B.
AFI 21–116.
- C.
AFI 33–106.
- D.
AFI 33–118.
- 91.What is a common problem with a mass alert system in a deployed environment?
- A.
Low power out.
- B.
Efficiency.
- C.
Cleanliness.
- D.
Reliability.
- 92.In the Whelen siren cabinet, what controls signal routing and power distribution of the system?
- A.
The landline board.
- B.
The control board.
- C.
The motherboard.
- D.
The radio board.
- 93.In the Whelen system, how many digits make up the dual tone multi frequency (DTMF) protocol.
- A.
6.
- B.
8.
- C.
10.
- D.
12.
- 94.In high frequency communications, your station’s self address is the address
- A.
The user programmed into your system.
- B.
It shares with other members.
- C.
Of an unprogrammed station.
- D.
Of other stations in the net.
- 95.What are the three part data handshake between calling and receiving stations?
- A.
Call, response, and acknowledgement.
- B.
Call, request, and acknowledgement.
- C.
Sound, handshake, and response.
- D.
Sound, call, and response.
- 96.Transmitting a signal on a particular frequency in order to determine that channel’s usability is referred to as
- A.
Call.
- B.
Sounding.
- C.
Networking.
- D.
Handshaking.
- 97.What is the maximum power of the AN/PRC–150 in FM mode?
- A.
5 watts.
- B.
10 watts.
- C.
15 watts.
- D.
20 watts.
- 98.What assembly on the AN/PRC–150 contains the keyboard and the liquid crystal display (LCD) that makes up the radio’s man-machine interface?
- A.
Chassis assembly.
- B.
Rear panel assembly.
- C.
Keyboard display unit.
- D.
Upper chassis assembly.
- 99.Where do the modulation and digital-to-analog conversion take place in the AN/PRC– 150?
- A.
Signal processing and control module.
- B.
INFOSEC printed wiring board.
- C.
Antenna coupler assembly.
- D.
Crypto assembly.
- 100.What is one of the simplest and most functional antennas in use?
- A.
Quarter-wave vertical.
- B.
Half-wave dipole.
- C.
Inverted-V.
- D.
GRA – 4.
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