3d154 Vol 3 &4
URE questions from Vol 3 & 4
Questions and Answers
- 1.
The low-density stream of charged particles emitted from the Sun is known as what?
- A.
Solar wind.
- B.
Solar radiation.
- C.
Ultraviolet rays.
- D.
Aurora borealis.
Correct Answer
A. Solar wind.Explanation
The low-density stream of charged particles emitted from the Sun is known as solar wind. Solar wind is a continuous flow of plasma consisting of electrons, protons, and alpha particles that are released from the outer layer of the Sun's atmosphere. These particles travel at high speeds and can have a significant impact on the Earth's magnetosphere and the formation of auroras.Rate this question:
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- 2.
Earth’s atmosphere is broken down into how many layers?
- A.
3
- B.
4
- C.
5
- D.
6
Correct Answer
C. 5Explanation
The Earth's atmosphere is broken down into five layers. These layers, starting from the Earth's surface and moving upwards, are the troposphere, stratosphere, mesosphere, thermosphere, and exosphere. Each layer has its own unique characteristics and plays a vital role in protecting and sustaining life on Earth.Rate this question:
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- 3.
What part of the atmosphere extends from Earth’s surface to heights of about 7.5 miles above Earth?
- A.
Ionosphere.
- B.
Mesosphere.
- C.
Troposphere.
- D.
Stratosphere.
Correct Answer
C. Troposphere.Explanation
The troposphere is the lowest layer of the Earth's atmosphere, extending from the surface up to about 7.5 miles above the Earth. It is where weather occurs and where most of the Earth's air mass is found. The other options, including the ionosphere, mesosphere, and stratosphere, are higher layers of the atmosphere that extend beyond the troposphere.Rate this question:
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- 4.
Which layer of the atmosphere includes the ionosphere?
- A.
Mesosphere.
- B.
Troposphere
- C.
Stratosphere.
- D.
Thermosphere.
Correct Answer
D. Thermosphere.Explanation
The ionosphere is a region within the Earth's atmosphere that contains a high concentration of ions and free electrons. It is located within the thermosphere, which is the layer of the atmosphere that extends from about 80 kilometers above the Earth's surface to the edge of space. The thermosphere is known for its high temperatures and is the layer where the auroras occur. Therefore, the correct answer is the thermosphere.Rate this question:
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- 5.
The presence or absence and height above Earth of the F1 and F2 ionospheric layers vary with the position of the
- A.
Sun.
- B.
Earth.
- C.
Moon.
- D.
Earth’s magnetic flux.
Correct Answer
A. Sun.Explanation
The presence or absence and height above Earth of the F1 and F2 ionospheric layers vary with the position of the Sun. The ionospheric layers are formed due to the interaction between solar radiation and the Earth's atmosphere. The Sun is the primary source of solar radiation, and its position in the sky directly affects the ionization levels and height of the ionospheric layers. Therefore, changes in the position of the Sun will cause variations in the presence, absence, and height of the F1 and F2 ionospheric layers.Rate this question:
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- 6.
What ionospheric layer reflects HF signals during the daytime?
- A.
D
- B.
E
- C.
F1
- D.
F2
Correct Answer
D. F2Explanation
During the daytime, the F2 layer of the ionosphere reflects HF signals. The F2 layer is the highest layer of the ionosphere, located approximately 200-400 km above the Earth's surface. It is known for its ability to reflect high-frequency (HF) radio waves, allowing for long-distance communication. This layer is particularly active during the daytime due to the presence of solar radiation, which ionizes the atoms and molecules in the F2 layer, making it highly reflective.Rate this question:
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- 7.
What regular ionospheric variation is attributed to Earth’s revolving around the Sun and the tilting of Earth’s axis during this rotation?
- A.
Daily variations.
- B.
Seasonal variations.
- C.
27-day sunspot cycle.
- D.
11-year sunspot cycle.
Correct Answer
B. Seasonal variations.Explanation
Seasonal variations in the ionosphere are attributed to Earth's revolving around the Sun and the tilting of Earth's axis during this rotation. As Earth moves around the Sun, the intensity and angle of sunlight reaching different parts of the planet change, resulting in variations in the ionosphere. Additionally, the tilt of Earth's axis causes different regions to experience different amounts of sunlight throughout the year, leading to seasonal variations in the ionosphere. Therefore, the correct answer is seasonal variations.Rate this question:
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- 8.
What irregular ionospheric variation can actually help HF communications by letting stations propagate on unusually high frequencies or allow sky wave propagation to close stations?
- A.
Sporadic E.
- B.
Solar flares.
- C.
Ionospheric storms.
- D.
Sudden ionospheric disturbances.
Correct Answer
A. Sporadic E.Explanation
Sporadic E is an irregular ionospheric variation that can help HF communications by allowing stations to propagate on unusually high frequencies or enabling sky wave propagation to close stations. Sporadic E is a phenomenon where patches of dense ionization form in the E region of the ionosphere, which is normally too weak for HF communication. These patches can reflect HF signals, allowing them to travel longer distances and at higher frequencies than usual. This can enhance HF communication capabilities and improve the range and quality of transmissions.Rate this question:
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- 9.
Which occurrence is not an irregular variation of the ionosphere?
- A.
Diurnal.
- B.
Solar flare.
- C.
Sporadic E.
- D.
Ionospheric storm.
Correct Answer
A. Diurnal.Explanation
Diurnal variation refers to the regular daily changes in the ionosphere due to the Sun's radiation. It is a predictable pattern that occurs every day, with ionization levels increasing during the day and decreasing at night. On the other hand, solar flares, sporadic E, and ionospheric storms are all irregular variations of the ionosphere that occur due to external factors such as solar activity, weather conditions, and geomagnetic disturbances. Therefore, diurnal is the only occurrence mentioned that is not considered an irregular variation of the ionosphere.Rate this question:
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- 10.
What irregular ionospheric variation is caused by the Sun rotating on its axis?
- A.
Daily variations.
- B.
Seasonal variations.
- C.
27-day sunspot cycle.
- D.
11-year sunspot cycle.
Correct Answer
C. 27-day sunspot cycle.Explanation
The irregular ionospheric variation caused by the Sun rotating on its axis is known as the 27-day sunspot cycle. Sunspots are dark spots on the surface of the Sun that are caused by intense magnetic activity. As the Sun rotates, these sunspots appear and disappear, causing fluctuations in the ionosphere. These fluctuations can affect radio communication and navigation systems on Earth. The 27-day cycle refers to the time it takes for the Sun to complete one rotation on its axis and for the sunspots to reappear in the same location.Rate this question:
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- 11.
What irregular ionospheric variation produces a burst of radiation across the electromagnetic spectrum and may last from minutes to hours in duration?
- A.
Sporadic E.
- B.
Solar flares.
- C.
27-day sunspot cycle.
- D.
11-year sunspot cycle.
Correct Answer
B. Solar flares.Explanation
Solar flares are irregular ionospheric variations that produce a burst of radiation across the electromagnetic spectrum. These flares can last from minutes to hours in duration. Sporadic E refers to a different type of irregular ionospheric variation, while the 27-day and 11-year sunspot cycles are not directly related to the production of bursts of radiation.Rate this question:
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- 12.
What device do you use to determine the virtual height of any ionospheric layer?
- A.
Multimeter.
- B.
Ohmmeter.
- C.
Horizontal radar.
- D.
Ionospheric sounder.
Correct Answer
D. Ionospheric sounder.Explanation
An ionospheric sounder is used to determine the virtual height of any ionospheric layer. It is specifically designed to measure the reflection height of radio waves in the ionosphere. By emitting a radio wave and analyzing the time it takes for the wave to return after being reflected by the ionosphere, the virtual height of the ionospheric layer can be determined. This information is crucial for understanding and studying the behavior of the ionosphere and its impact on communication and navigation systems.Rate this question:
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- 13.
F-layer critical frequencies generally fall in what frequency range?
- A.
1 to 15 MHz.
- B.
2 to 6 MHz.
- C.
3 to 30 MHz.
- D.
15 to 30 MHz.
Correct Answer
A. 1 to 15 MHz.Explanation
The F-layer critical frequencies generally fall in the frequency range of 1 to 15 MHz. This means that the maximum usable frequency for long-distance radio communication during the day is typically between 1 and 15 MHz. Frequencies outside of this range may not be reflected back to Earth by the F-layer, resulting in reduced or no communication.Rate this question:
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- 14.
What is the area of silence between the weakest ground wave reception and the point the sky wave first returns to Earth called?
- A.
Skip zone.
- B.
Diffraction.
- C.
Skip distance.
- D.
Skip difference.
Correct Answer
A. Skip zone.Explanation
The area of silence between the weakest ground wave reception and the point the sky wave first returns to Earth is called the skip zone. This refers to the region where the signal strength is too weak to be received by ground wave propagation, but the sky wave has not yet returned to the Earth's surface.Rate this question:
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- 15.
What component of the ground wave travels directly from the transmit antenna to the receive antenna?
- A.
Direct.
- B.
Surface.
- C.
Skip distance.
- D.
Skip difference.
Correct Answer
A. Direct.Explanation
The component of the ground wave that travels directly from the transmit antenna to the receive antenna is called the direct wave. This wave follows a straight line path and does not interact with the ground or any other objects. It is the shortest and fastest path between the two antennas, resulting in the strongest signal strength.Rate this question:
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- 16.
What wave propagation effect makes use of general weather phenomena and air turbulence to refract radio waves to the receiving station?
- A.
Sky.
- B.
Surface.
- C.
Reflected.
- D.
Tropospheric.
Correct Answer
D. Tropospheric.Explanation
Tropospheric wave propagation refers to the bending or refraction of radio waves in the lower part of the Earth's atmosphere, known as the troposphere. This phenomenon occurs due to general weather phenomena and air turbulence, which cause variations in temperature, pressure, and humidity in the troposphere. These variations in the refractive index of the air can cause radio waves to be bent and follow a curved path, allowing them to reach the receiving station even if they would normally be obstructed by the Earth's curvature. Therefore, the correct answer is tropospheric.Rate this question:
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- 17.
The area where the transmitter antenna and receiver antennas intersect and share common airspace in troposcatter propagation is known as
- A.
Critical angle.
- B.
Scatter volume.
- C.
Critical zone.
- D.
Scatter angle.
Correct Answer
B. Scatter volume.Explanation
In troposcatter propagation, the scatter volume refers to the area where the transmitter antenna and receiver antennas intersect and share common airspace. This is the region where the scattering of the radio waves occurs, allowing for communication over long distances. The scatter volume is crucial in troposcatter propagation as it determines the effectiveness and quality of the communication link between the transmitter and receiver.Rate this question:
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- 18.
What is the most common piece of equipment for troposcatter communications in the Air Force today?
- A.
AN/FRC–107.
- B.
AN/GRC–206.
- C.
AN/TPQ–43.
- D.
AN/TRC–170.
Correct Answer
D. AN/TRC–170.Explanation
The AN/TRC-170 is the most common piece of equipment for troposcatter communications in the Air Force today.Rate this question:
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- 19.
Which data item is not found on a Spectrum XXI HF sky wave analysis output?
- A.
Local time period.
- B.
Transmit location.
- C.
Universal time period.
- D.
Type of radio being used.
Correct Answer
D. Type of radio being used.Explanation
The Spectrum XXI HF sky wave analysis output provides information about various data items related to HF sky wave analysis. The local time period, transmit location, and universal time period are all important factors in analyzing HF sky wave propagation. However, the type of radio being used is not typically included in this analysis output as it is not directly relevant to the analysis of HF sky wave propagation.Rate this question:
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- 20.
Automated link establishment (ALE) equipment is comprised of
- A.
Computer-controlled HF radios.
- B.
Advanced Global Positioning System (GPS) landing systems.
- C.
Land mobile radio (LMR) units that incorporate cellular phones.
- D.
Military strategic and tactical relay (MILSTAR) satellite controller systems.
Correct Answer
A. Computer-controlled HF radios.Explanation
The correct answer is computer-controlled HF radios. Automated link establishment (ALE) equipment refers to a system that uses computer-controlled high-frequency (HF) radios to establish and maintain communication links. These radios are capable of automatically selecting the best frequency and modulation technique for reliable communication. They are commonly used in military and emergency communication systems where reliable long-range communication is required. The other options mentioned in the question, such as advanced GPS landing systems, land mobile radios with cellular phones, and MILSTAR satellite controller systems, are not directly related to ALE equipment.Rate this question:
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- 21.
What do computer-controlled automated link establishment (ALE) radios use to allow them to handshake with other ALE radios in the network
- A.
Formulas.
- B.
Channels.
- C.
Protocols.
- D.
Distant station.
Correct Answer
C. Protocols.Explanation
Computer-controlled automated link establishment (ALE) radios use protocols to allow them to handshake with other ALE radios in the network. Protocols are a set of rules and procedures that govern the communication between devices. In the case of ALE radios, protocols define how the radios establish and maintain connections with each other. These protocols ensure that the radios can effectively communicate and exchange data, allowing for seamless communication within the network.Rate this question:
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- 22.
What is the first thing you look at when selecting an antenna for a HF circuit?
- A.
Power capability.
- B.
Type of equipment.
- C.
Type of propagation.
- D.
Authorized frequencies.
Correct Answer
C. Type of propagation.Explanation
When selecting an antenna for a HF circuit, the first thing to consider is the type of propagation. This is because different types of propagation, such as ground wave, sky wave, or line-of-sight, require different antenna designs and characteristics. By understanding the type of propagation, one can choose an antenna that is optimized for the specific conditions and maximize the performance of the HF circuit.Rate this question:
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- 23.
What is the worst type of antenna to use for sky wave circuits?
- A.
Whip.
- B.
Long-wire.
- C.
Inverted V.
- D.
Rotatable log periodic antenna (RLPA).
Correct Answer
A. Whip.Explanation
A whip antenna is the worst type of antenna to use for sky wave circuits because it is vertically polarized and has a low radiation angle. Sky wave propagation relies on signals being reflected off the ionosphere, and a low radiation angle will result in a significant portion of the signal being absorbed by the ground instead of being reflected back. Additionally, whip antennas have a limited radiation pattern and are less efficient at transmitting and receiving signals over long distances.Rate this question:
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- 24.
You can make a long-wire antenna directional by
- A.
Switching propagation modes.
- B.
Placing a balun on the antenna input.
- C.
Decreasing the power output of the radio.
- D.
Placing a terminating device at the distant station end of the antenna.
Correct Answer
D. Placing a terminating device at the distant station end of the antenna.Explanation
Placing a terminating device at the distant station end of the antenna can make a long-wire antenna directional. This is because the terminating device absorbs the energy that is not radiated in the desired direction, preventing it from reflecting back towards the source. By effectively terminating the antenna, the signal is focused in the desired direction, increasing the antenna's directivity and making it more directional.Rate this question:
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- 25.
What type of antenna should be used for low frequency and short-distance HF circuits?
- A.
Long-wire.
- B.
Inverted-L.
- C.
Inverted-V.
- D.
Near vertical incidence sky wave (NVIS).
Correct Answer
D. Near vertical incidence sky wave (NVIS).Explanation
The near vertical incidence sky wave (NVIS) antenna should be used for low frequency and short-distance HF circuits. This type of antenna is designed to radiate signals at high angles, allowing them to be reflected back to Earth over short distances. NVIS antennas are commonly used for communication within a specific region or coverage area, making them ideal for low frequency and short-distance HF circuits.Rate this question:
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- 26.
Because of extreme congestion, in which frequency band is new land mobile radio (LMR) assignments usually made?
- A.
29.89 to 50 MHz.
- B.
138 to 144 MHz or 406 to 420 MHz.
- C.
148 to 150.8 MHz or 162 to 174 MHz.
- D.
1,350 to 1,400 MHz.
Correct Answer
B. 138 to 144 MHz or 406 to 420 MHz.Explanation
Due to extreme congestion, new land mobile radio (LMR) assignments are usually made in the frequency band of 138 to 144 MHz or 406 to 420 MHz. This is because these frequency bands are less crowded and therefore provide better opportunities for clear and reliable communication.Rate this question:
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- 27.
Where can you find in most current information on the fielding of Land Mobile Radio systems?
- A.
Military Communications-Electronics Board (MCEB) Pub 7.
- B.
Air Force Instruction (AFI) 33–118, Electromagnetic Spectrum Management.
- C.
Air Force Manual (AFMAN) 33–120, Radio Frequency (RF) Spectrum Management.
- D.
National Telecommunications and Information Administration (NTIA) manual.
Correct Answer
D. National Telecommunications and Information Administration (NTIA) manual.Explanation
The most current information on the fielding of Land Mobile Radio systems can be found in the National Telecommunications and Information Administration (NTIA) manual.Rate this question:
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- 28.
What Air Force Instruction (AFI) governs the tracking and reporting of personal wireless communications systems (PWCS) assets?
- A.
Military Communications-Electronics Board (MCEB) Pub 7.
- B.
Air Force Manual (AFMAN) 33–120, Radio Frequency (RF) Spectrum Management.
- C.
AFI 33–106, Managing High Frequency Radios, Personal Wireless Communication Systems, and the Military Affiliate Radio System.
- D.
National Telecommunications and Information Administration (NTIA) Manual of Regulations and Procedures for Federal Radio Frequency Management.
Correct Answer
C. AFI 33–106, Managing High Frequency Radios, Personal Wireless Communication Systems, and the Military Affiliate Radio System. -
- 29.
Most repeater systems operate in what type of configuration?
- A.
Remote.
- B.
Tactical.
- C.
Simplex.
- D.
Half duplex.
Correct Answer
D. Half duplex.Explanation
Most repeater systems operate in a half duplex configuration, which means that they can either transmit or receive signals at one time, but not both simultaneously. In a half duplex system, the repeater receives a signal from one device and then retransmits it to another device. This configuration allows for efficient use of the communication channel, as only one device can transmit at a time, reducing the chances of collisions and interference.Rate this question:
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- 30.
What made trunking possible in land mobile radio (LMR) systems?
- A.
Better antennas.
- B.
Microprocessors.
- C.
Frequency diversity.
- D.
Stabilized transmitters.
Correct Answer
B. Microprocessors.Explanation
Microprocessors made trunking possible in land mobile radio (LMR) systems. Trunking is a technology that allows multiple users to share a set of frequencies efficiently. With the introduction of microprocessors, it became possible to dynamically assign frequencies to users based on demand, rather than using fixed frequency allocations. Microprocessors enabled the development of sophisticated control systems that could manage the allocation of frequencies, handle call setup and tear down, and provide other advanced features such as prioritization and encryption. This greatly increased the capacity and efficiency of LMR systems, making trunking a reality.Rate this question:
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- 31.
Air Force activities must be careful in procuring and using nonlicensed devices. Which type of equipment is not in this category?
- A.
Biomedical telemetry.
- B.
Wireless microphones.
- C.
Intersquad Land mobile radios.
- D.
Wireless Local Area Networks access points.
Correct Answer
C. Intersquad Land mobile radios.Explanation
Intersquad Land mobile radios are not considered nonlicensed devices because they operate on specific frequency bands that are allocated for military use. Therefore, Air Force activities do not need to be as cautious when procuring and using these radios compared to other nonlicensed devices such as biomedical telemetry, wireless microphones, and wireless local area network access points.Rate this question:
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- 32.
What type of devices does not require a NTIA approved frequency assignment, but the DOD may require them to be registered in the FRRS?
- A.
Unlicensed.
- B.
Licensed.
- C.
ARC–164.
- D.
PRC–139.
Correct Answer
A. Unlicensed.Explanation
Unlicensed devices do not require a NTIA approved frequency assignment, but the DOD may require them to be registered in the FRRS. This means that these devices can operate on frequencies that are not specifically assigned to them, but they still need to be registered with the DOD for tracking and coordination purposes.Rate this question:
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- 33.
What antenna type is used for mobile and portable land mobile radio (LMR) installations?
- A.
Yagi.
- B.
Periodic array.
- C.
Reflector.
- D.
Whip.
Correct Answer
D. Whip.Explanation
The whip antenna is commonly used for mobile and portable land mobile radio (LMR) installations. This type of antenna is compact, flexible, and easy to install, making it ideal for mobile applications. It is designed to radiate and receive radio signals in a 360-degree pattern, allowing for effective communication in various directions. The whip antenna is also durable and can withstand harsh weather conditions, making it suitable for outdoor use. Overall, the whip antenna is a practical choice for mobile and portable LMR installations.Rate this question:
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- 34.
Radio horizon distance equates to what?
- A.
Line of sight.
- B.
Line of sight and over the horizon.
- C.
Distance of travel of one wavelength of a radio wave.
- D.
A distance equal to approximately 15 percent greater than the optical horizon distance.
Correct Answer
D. A distance equal to approximately 15 percent greater than the optical horizon distance.Explanation
The radio horizon distance refers to the maximum distance at which a radio signal can be transmitted and received without any obstacles or interference. It is typically greater than the optical horizon distance due to the nature of radio waves and their ability to diffract and bend around obstacles. The correct answer states that the radio horizon distance is approximately 15 percent greater than the optical horizon distance, indicating that radio signals can travel further than what can be seen with the naked eye.Rate this question:
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- 35.
System gains or losses can be calculated by
- A.
Calculating the overall effective transmitted power (ETP) of the system against the received signal level (RSL).
- B.
Comparing the new system values against its old value at the Log rate which applies to that factor.
- C.
Dividing the overall gain of the system by the overall system attenuation.
- D.
Comparing the system values against known standards.
Correct Answer
B. Comparing the new system values against its old value at the Log rate which applies to that factor.Explanation
The correct answer is comparing the new system values against its old value at the Log rate which applies to that factor. This method allows for the evaluation of any changes or improvements in the system by comparing the current values with the previous values at the appropriate logarithmic rate. By doing so, it provides a reliable measure of the system's performance and any gains or losses that may have occurred.Rate this question:
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- 36.
Which radio covers the entire 136 to 174 MHz band and is used by special operations forces for squad communications?
- A.
AN/PRC–128 (Scope Shield).
- B.
Miniature Secure Handheld Radio (MSHR).
- C.
Multiband Inter/Intra Team Radio (MBITR).
- D.
Single channel ground airborne radio system (SINCGARS).
Correct Answer
B. Miniature Secure Handheld Radio (MSHR).Explanation
The correct answer is Miniature Secure Handheld Radio (MSHR). This radio covers the entire 136 to 174 MHz band and is used by special operations forces for squad communications. This implies that it is specifically designed for secure and reliable communication within a squad, making it an ideal choice for special operations forces. The other options mentioned do not cover the entire frequency band or may not be specifically designed for squad communications.Rate this question:
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- 37.
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.
Correct Answer
A. Dwell time.Explanation
In frequency hopping operation, the interval at which each transmitter remains on a given frequency for a specific time is known as dwell time. This refers to the duration for which the transmitter stays on a particular frequency before switching to another. It determines how long the transmitter will transmit on a specific frequency before hopping to the next one in the sequence.Rate this question:
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- 38.
What type of key is required to initiate the pseudo random algorithm for choosing frequencies?
- A.
Cipher.
- B.
Crypto ignition.
- C.
Computer security (COMSEC).
- D.
Transmission security (TRANSEC).
Correct Answer
D. Transmission security (TRANSEC).Explanation
The correct answer is Transmission security (TRANSEC). In order to initiate the pseudo random algorithm for choosing frequencies, a key related to transmission security is required. TRANSEC is a term used in computer security to refer to measures taken to secure the transmission of sensitive information. This includes the use of encryption algorithms and keys to ensure the confidentiality and integrity of the data being transmitted. Therefore, the key required to initiate the pseudo random algorithm for choosing frequencies falls under the category of transmission security (TRANSEC).Rate this question:
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- 39.
What transmission security (TRANSEC) parameter ensures hopping sequences are synchronized in each net and may be an internal or external input to the system?
- A.
Hop set.
- B.
Net number.
- C.
Time reference.
- D.
Hopping pattern.
Correct Answer
C. Time reference.Explanation
The correct answer is "Time reference." In transmission security (TRANSEC), the time reference parameter ensures that hopping sequences are synchronized in each net. It can be an internal or external input to the system, providing a common time base for all nodes in the network. This synchronization is crucial for secure and reliable communication within the network.Rate this question:
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- 40.
What transmission security (TRANSEC) parameter forces two transceivers to follow the same hopping sequence?
- A.
Hop set.
- B.
Net number.
- C.
Time reference.
- D.
Hopping pattern.
Correct Answer
B. Net number.Explanation
The correct answer is "Net number". In a transmission security (TRANSEC) system, the net number parameter is used to ensure that two transceivers follow the same hopping sequence. This means that they will both switch between frequencies in the same predetermined order, which helps to maintain secure communication by preventing unauthorized access or interception. The net number serves as a synchronization mechanism for the transceivers, ensuring that they are on the same page when it comes to frequency hopping.Rate this question:
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- 41.
What is the most widely known and used spread spectrum system?
- A.
Time hopping systems.
- B.
Direct sequence spread spectrum.
- C.
Pulse frequency modulated systems.
- D.
Frequency hopping spread spectrum.
Correct Answer
B. Direct sequence spread spectrum.Explanation
Direct sequence spread spectrum is the most widely known and used spread spectrum system. This system uses a spreading code to spread the bandwidth of the signal, making it more resistant to interference and jamming. It is commonly used in various wireless communication technologies, including Wi-Fi and Bluetooth. Time hopping systems, pulse frequency modulated systems, and frequency hopping spread spectrum are also spread spectrum systems, but they are not as widely known and used as direct sequence spread spectrum.Rate this question:
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- 42.
Which spread spectrum system varies the period and duty cycle of a pulsed radio frequency (RF) carrier under the control of a coded sequence?
- A.
Time hopping.
- B.
Direct sequence.
- C.
Frequency hopping.
- D.
Pulsed frequency modulation.
Correct Answer
A. Time hopping.Explanation
Time hopping is a spread spectrum system that varies the period and duty cycle of a pulsed radio frequency (RF) carrier under the control of a coded sequence. In time hopping, the RF carrier signal is divided into small time slots, and the transmitter and receiver synchronize their hopping patterns based on a predetermined code sequence. This allows for increased resistance to interference and improved security in wireless communication systems.Rate this question:
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- 43.
What was the old power level restriction for Federal Communication Commission (FCC) spread spectrum operations?
- A.
Less than 1 microwatt.
- B.
Less than 1 watt.
- C.
10 watts.
- D.
100 watts.
Correct Answer
B. Less than 1 watt.Explanation
The old power level restriction for Federal Communication Commission (FCC) spread spectrum operations was less than 1 watt. This means that the power level used for spread spectrum operations had to be below 1 watt.Rate this question:
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- 44.
In what frequency band does the HAVE QUICK (HQ) radio operate?
- A.
HF.
- B.
VHF.
- C.
UHF.
- D.
EHF.
Correct Answer
C. UHF.Explanation
The correct answer is UHF. UHF stands for Ultra High Frequency, which refers to the frequency band between 300 MHz and 3 GHz. HAVE QUICK (HQ) radio operates in this frequency band, which is commonly used for military communications due to its ability to provide long-range communication and resistance to interference.Rate this question:
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- 45.
Which radio is not a HAVE QUICK (HQ) type?
- A.
Basic HQ.
- B.
HQ II.
- C.
HQ IIA.
- D.
HQ III.
Correct Answer
D. HQ III.Explanation
The question asks for a radio that is not a HAVE QUICK (HQ) type. The options provided are Basic HQ, HQ II, HQ IIA, and HQ III. The correct answer is HQ III because it is the only option that does not have the term "HQ" in its name. Therefore, HQ III is not a HAVE QUICK (HQ) type of radio.Rate this question:
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- 46.
Which term describes the specific order in which HAVE QUICK (HQ) radios switch from one frequency to the next?
- A.
Hop-set.
- B.
Hop-rate.
- C.
Hopping pattern.
- D.
Net number assignment.
Correct Answer
C. Hopping pattern.Explanation
The term that describes the specific order in which HAVE QUICK (HQ) radios switch from one frequency to the next is "hopping pattern." This refers to the predetermined sequence in which the radios change frequencies during communication.Rate this question:
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- 47.
In what frequency band does the Single Channel Ground and Airborne Radio System (SINCGARS) radio operate?
- A.
HF
- B.
VHF
- C.
UHF
- D.
EHF
Correct Answer
B. VHFExplanation
The Single Channel Ground and Airborne Radio System (SINCGARS) radio operates in the VHF frequency band. VHF stands for Very High Frequency and typically ranges from 30 to 300 MHz. This frequency band is commonly used for communication purposes as it provides good range and penetration through obstacles such as buildings and foliage. SINCGARS radios are widely used by the military for secure voice and data communication in various operational environments.Rate this question:
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- 48.
How many types of Single Channel Ground and Airborne Radio System (SINCGARS) aircraft radios are there?
- A.
2
- B.
3
- C.
4
- D.
6
Correct Answer
B. 3Explanation
There are three types of Single Channel Ground and Airborne Radio System (SINCGARS) aircraft radios.Rate this question:
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- 49.
Which cryptographic key is required to encrypt normal voice and data traffic for the Single Channel Ground and Airborne Radio System (SINCGARS) radio?
- A.
Key encryption key.
- B.
Word-of-day insertion.
- C.
Traffic encryption key.
- D.
Transmission security key.
Correct Answer
C. Traffic encryption key.Explanation
The correct answer is traffic encryption key. The Single Channel Ground and Airborne Radio System (SINCGARS) radio requires a traffic encryption key to encrypt normal voice and data traffic. This key is used to protect the confidentiality and integrity of the transmitted information, ensuring that it cannot be intercepted or tampered with by unauthorized individuals.Rate this question:
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- 50.
The joint tactical radio system (JTRS) is a family of radios designed aroun
- A.
HAVE QUICK algorithms.
- B.
Software communications architecture (SCA).
- C.
Frequency diversity communications systems.
- D.
Single channel ground airborne radio system (SINCGARS) algorithms.
Correct Answer
B. Software communications architecture (SCA).Explanation
The correct answer is software communications architecture (SCA). The question is asking about the design of the joint tactical radio system (JTRS) and which feature it is based on. The JTRS is designed around the software communications architecture (SCA), which is a set of specifications that allows for the development of software-defined radios. This architecture enables interoperability and flexibility in communication systems by separating the hardware from the software, allowing for easy upgrades and reconfiguration.Rate this question:
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Mar 20, 2023Quiz Edited by
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Jul 15, 2013Quiz Created by
Juney329
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