3d1x5 Volume 1 (Ure)

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CDCs Quizzes & Trivia

Volume 1 for 3D1X5 CDCs


Questions and Answers
  • 1. 

    What is the required angle of incidence necessary to get a reflection back to a light source?

    • A.

      45

    • B.

      90

    • C.

      135

    • D.

      180

    Correct Answer
    B. 90
    Explanation
    When light reflects back to its source, it does so at an angle of 90 degrees. This is known as the angle of incidence. At this angle, the light ray hits the surface and bounces directly back in the opposite direction, creating a reflection. Any other angle of incidence would result in the light ray bouncing off at a different angle, rather than returning to the source. Therefore, the required angle of incidence necessary to get a reflection back to a light source is 90 degrees.

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  • 2. 

    When a pulse of radio frequency energy is transmitted, it travels at

    • A.

      The speed of light

    • B.

      The speed of sound

    • C.

      One-half the speed of light

    • D.

      One-half the speed of sound

    Correct Answer
    A. The speed of light
    Explanation
    When a pulse of radio frequency energy is transmitted, it travels at the speed of light. This is because radio frequency energy is a form of electromagnetic radiation, which travels through space at the speed of light. The speed of light is approximately 299,792,458 meters per second in a vacuum. Therefore, radio frequency energy, being a type of electromagnetic wave, also travels at this speed.

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  • 3. 

    Approximately how long does it take for radio frequency energy to travel 1 nautical mile to a target and return to the radar?

    • A.

      3.09 us

    • B.

      6.18 us

    • C.

      9.27 us

    • D.

      12.36 us

    Correct Answer
    D. 12.36 us
    Explanation
    Radio frequency energy travels at the speed of light, which is approximately 299,792,458 meters per second. Since there are 1,852 meters in a nautical mile, it would take approximately 1.0025 microseconds (us) for the energy to travel 1 nautical mile to the target and an additional 1.0025 microseconds (us) to return to the radar. Therefore, the total time would be approximately 2.005 microseconds (us). However, the closest option to this value is 12.36 us, which is not an accurate representation of the time it takes for radio frequency energy to travel 1 nautical mile and return to the radar.

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  • 4. 

    You can identify the maximum detection range of a radar by dividing the time of one radar mile into the

    • A.

      Transmitter on-time

    • B.

      Transmitter off-time

    • C.

      Pulse recurrence time

    • D.

      Pulse repetition frequency

    Correct Answer
    C. Pulse recurrence time
    Explanation
    The pulse recurrence time refers to the time it takes for a radar to emit one pulse and then emit another pulse. By dividing the time of one radar mile into the pulse recurrence time, we can determine the maximum detection range of the radar. This is because the pulse recurrence time directly affects the time it takes for the radar to cover a certain distance. The longer the pulse recurrence time, the longer it takes for the radar to cover a mile, indicating a shorter detection range. Conversely, a shorter pulse recurrence time allows the radar to cover a mile more quickly, indicating a longer detection range.

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  • 5. 

    What characteristic of frequency does a radar target moving towards the radar exhibit?

    • A.

      A lower frequency than the original broadcast

    • B.

      A higher frequency than the original broadcast

    • C.

      No apparent frequency change than the original broadcast

    • D.

      Oscillating lower and higher frequency changes in respect to the original broadcast

    Correct Answer
    B. A higher frequency than the original broadcast
    Explanation
    When a radar target is moving towards the radar, it exhibits a higher frequency than the original broadcast. This is known as the Doppler effect, which causes an increase in frequency when the source and observer are approaching each other. This increase in frequency is due to the compression of the waves as the target moves closer to the radar.

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  • 6. 

    Which radar subassembly ensures all circuits connected with the radar operate in a definite timed relationship?

    • A.

      Synchronizer

    • B.

      Transmitter

    • C.

      Modulator

    • D.

      Duplexer

    Correct Answer
    A. Synchronizer
    Explanation
    A synchronizer is a radar subassembly that ensures all circuits connected with the radar operate in a definite timed relationship. It is responsible for coordinating the timing of various components within the radar system, ensuring that they work together harmoniously. This synchronization is crucial for accurate and efficient radar operation, as it allows for precise timing of signals, data processing, and transmission. Without a synchronizer, the radar system may experience timing errors or inconsistencies, leading to inaccurate readings or malfunctioning of the radar system.

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  • 7. 

    What radar subassembly allows the radar system to transmit and receive from the same antenna?

    • A.

      Synchronizer

    • B.

      Transmitter

    • C.

      Modulator

    • D.

      Duplexer

    Correct Answer
    D. Duplexer
    Explanation
    A duplexer is a radar subassembly that allows the radar system to transmit and receive from the same antenna. It is responsible for separating the transmitted and received signals, allowing them to be processed separately. This is important because radar systems operate by sending out a signal and then detecting the echo that is reflected back. The duplexer ensures that the transmitted signal does not interfere with the received signal, allowing for accurate detection and measurement of targets.

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  • 8. 

    An antenna is said to be reciprocal if

    • A.

      It is nonlinear

    • B.

      It transmits patterns

    • C.

      It contains ferrite devices

    • D.

      Its transmit and receive patterns are identical

    Correct Answer
    D. Its transmit and receive patterns are identical
    Explanation
    A reciprocal antenna is one where the transmit and receive patterns are identical. This means that the antenna behaves the same way when transmitting a signal as it does when receiving a signal. In other words, the antenna has the same radiation pattern regardless of whether it is transmitting or receiving. This property is important in many applications, such as wireless communication systems, where it is desirable for the antenna to have consistent performance in both transmit and receive modes.

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  • 9. 

    Which feedhorn is used only for receiving?

    • A.

      Active

    • B.

      Linear

    • C.

      Passive

    • D.

      Circular

    Correct Answer
    C. Passive
    Explanation
    Passive feedhorns are used only for receiving signals. Unlike active feedhorns, they do not have any active components or electronics that amplify or modify the received signals. Instead, passive feedhorns simply collect and direct the incoming signals towards the receiver without any additional processing. This makes them suitable for applications where only receiving signals is required, such as in satellite communication systems or radio telescopes.

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  • 10. 

    One use for the beam-lobing switch of the multi-feedhorn system is to

    • A.

      Raise the effective beam coverage by 3

    • B.

      Dummy load the lower 3 of the transmitted beam

    • C.

      Route the received signal from the number one feedhorn to a dummy load

    • D.

      Vary low-level coverage by routing more radio frequency through one feedhorn

    Correct Answer
    C. Route the received signal from the number one feedhorn to a dummy load
    Explanation
    The beam-lobing switch of the multi-feedhorn system is used to route the received signal from the number one feedhorn to a dummy load. This means that instead of allowing the received signal to be processed or transmitted further, it is redirected to a dummy load, which absorbs the signal. This can be useful in certain situations where the received signal from the number one feedhorn is not desired or needs to be isolated for specific purposes.

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  • 11. 

    What does the distribution of electromagnetic energy from the antenna over the aperture determine?

    • A.

      Main lobe gain

    • B.

      Pattern of the antenna

    • C.

      Probability of interference

    • D.

      Susceptibility of the antenna

    Correct Answer
    B. Pattern of the antenna
    Explanation
    The distribution of electromagnetic energy from the antenna over the aperture determines the pattern of the antenna. The pattern of the antenna refers to the directional characteristics of the antenna, including the shape and strength of the radiation pattern. This pattern determines how the antenna radiates or receives energy in different directions. By controlling the distribution of energy over the aperture, the antenna's pattern can be adjusted to optimize its performance for specific applications such as maximizing signal strength in a particular direction or minimizing interference from unwanted directions.

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  • 12. 

    The shape of the beam of radar energy and its antenna pattern depend on the radar’s

    • A.

      Gain

    • B.

      Location

    • C.

      Purpose

    • D.

      Power

    Correct Answer
    C. Purpose
    Explanation
    The shape of the beam of radar energy and its antenna pattern depend on the radar's purpose. Different radar systems are designed for specific purposes, such as air traffic control, weather monitoring, or military surveillance. Each purpose requires a specific beam shape and antenna pattern to effectively achieve its objectives. For example, a radar system used for air traffic control needs a wide beam to cover a large area, while a radar system used for military surveillance may require a narrow beam for precise targeting. Therefore, the purpose of the radar system determines the shape of the beam and antenna pattern.

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  • 13. 

    The scanning method used by the radar system refers to the

    • A.

      Direction of energy into an appropriately shaped beam

    • B.

      Orientation of the electromagnetic wave as it travels through space

    • C.

      Motion of the antenna axis (of the beam) as the radar looks for an aircraft

    • D.

      Efficient launch and reception of electromagnetic energy in the atmosphere or space

    Correct Answer
    C. Motion of the antenna axis (of the beam) as the radar looks for an aircraft
    Explanation
    The scanning method used by the radar system refers to the motion of the antenna axis (of the beam) as the radar looks for an aircraft. This means that the radar system moves its antenna in a specific pattern to cover a certain area and search for any aircraft within that area. By scanning the antenna, the radar system can detect and track the movement of the aircraft. This scanning method allows the radar system to effectively locate and monitor aircraft in its surroundings.

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  • 14. 

    What scan is identified at the electronic countermeasure receiver by its regular intervals between illuminations?

    • A.

      Raster

    • B.

      Conical

    • C.

      Circular

    • D.

      Monopulse

    Correct Answer
    C. Circular
    Explanation
    Circular scan is identified at the electronic countermeasure receiver by its regular intervals between illuminations. This type of scan involves rotating the antenna in a circular pattern, illuminating the target area at regular intervals. This allows for a systematic coverage of the area, ensuring that all targets within the scan range are detected and tracked. The regular intervals between illuminations help in distinguishing the circular scan from other types of scans.

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  • 15. 

    What scan system uses a thin beam to cover a rectangular area by sweeping the area horizontally with the angle of elevation incrementally stepped up or down with each horizontal sweep of the sector?

    • A.

      Raster

    • B.

      Conical

    • C.

      Circular

    • D.

      Monopulse

    Correct Answer
    A. Raster
    Explanation
    The correct answer is Raster. A raster scan system uses a thin beam to cover a rectangular area by sweeping the area horizontally with the angle of elevation incrementally stepped up or down with each horizontal sweep of the sector. This method is commonly used in computer monitors and television screens to display images line by line.

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  • 16. 

    Which scan radar is also used in the acquisition phase by some airborne intercept radars?

    • A.

      Raster

    • B.

      Conical

    • C.

      Circular

    • D.

      Monopulse

    Correct Answer
    A. Raster
    Explanation
    Some airborne intercept radars use the raster scan radar in the acquisition phase. The raster scan radar is a type of radar that scans the target area in a systematic pattern, moving horizontally and vertically. This scanning technique allows the radar to gather information from multiple angles and provide a more accurate picture of the target's location. In the acquisition phase, the radar is searching for and acquiring targets, and the raster scan radar is used for this purpose.

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  • 17. 

    Which scan radar gets its name from the fact that each echo pulse from the aircraft being tracked yields a new azimuth and elevation correction signal?

    • A.

      Raster

    • B.

      Conical

    • C.

      Circular

    • D.

      Monopulse

    Correct Answer
    D. Monopulse
    Explanation
    Monopulse scan radar gets its name from the fact that each echo pulse from the aircraft being tracked yields a new azimuth and elevation correction signal. This means that the radar is able to continuously update and correct the position of the tracked aircraft based on the echoes it receives. This capability allows for more accurate tracking and targeting of the aircraft, making monopulse radar a preferred choice in many applications.

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  • 18. 

    In which scan radar does the antenna rotate on an azimuth sweep, while the elevation angle rises slowly from 0 to 90?

    • A.

      Palmer

    • B.

      Helical

    • C.

      Palmer/Raster

    • D.

      Track-While

    Correct Answer
    B. Helical
    Explanation
    In a helical scan radar, the antenna rotates on an azimuth sweep while the elevation angle rises slowly from 0° to 90°. This type of radar scan allows for a continuous and smooth coverage of the entire sky, making it suitable for applications where a wide range of elevation angles need to be monitored. The helical scan pattern ensures that the radar can detect targets at different altitudes without any gaps in coverage.

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  • 19. 

    What causes delayed, but separate, pulses?

    • A.

      Simultaneous reception of pulse-type information

    • B.

      Near-simultaneous reception of pulse-type information

    • C.

      Electromagnetic (EM) waves reach the receiving antenna by direct paths

    • D.

      EM waves reach the receiving antenna by indirect paths

    Correct Answer
    B. Near-simultaneous reception of pulse-type information
    Explanation
    Near-simultaneous reception of pulse-type information causes delayed, but separate, pulses. This means that the pulses are received almost at the same time, but with a slight delay between them. This could be due to factors such as the distance between the source of the pulses and the receiving antenna, as well as any obstacles or interference that may cause slight variations in the arrival time of the pulses.

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  • 20. 

    Attempts to reduce multipath effects on radar tracking accuracy include the use of

    • A.

      Off-axis tracking

    • B.

      Frequency agility

    • C.

      Monopulse radar

    • D.

      Off-boresight tracking

    Correct Answer
    B. Frequency agility
    Explanation
    Frequency agility refers to the ability of a radar system to rapidly change its operating frequency. This technique is used to mitigate the effects of multipath, which is the phenomenon where radar signals bounce off objects and arrive at the receiver through multiple paths. By changing the frequency, the radar system can avoid or minimize the interference caused by these reflected signals, improving the accuracy of radar tracking.

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  • 21. 

    What type of radar system uses a B-scan indicator?

    • A.

      Long-range surveillance

    • B.

      Airport surveillance

    • C.

      Precision approach

    • D.

      Weather

    Correct Answer
    C. Precision approach
    Explanation
    A radar system that uses a B-scan indicator is typically used for precision approach. This type of radar system provides detailed information about the altitude, distance, and position of aircraft during the final stages of landing. It allows pilots to accurately align their aircraft with the runway and make a safe landing. The B-scan indicator provides a visual representation of the aircraft's position relative to the runway, helping pilots to make precise adjustments during the approach.

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  • 22. 

    What target information is provided by a plan-position indicator?

    • A.

      Azimuth only

    • B.

      Elevation only

    • C.

      Range and azimuth

    • D.

      Elevation and range

    Correct Answer
    C. Range and azimuth
    Explanation
    A plan-position indicator provides information about the range and azimuth of a target. Range refers to the distance between the radar and the target, while azimuth refers to the angle between the radar's reference point and the target, measured in a horizontal plane. This information helps in determining the location and movement of the target in relation to the radar.

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  • 23. 

    In a Raster scan indicator, how many vertical scan periods does it take to produce one complete picture?

    • A.

      1

    • B.

      2

    • C.

      3

    • D.

      4

    Correct Answer
    B. 2
    Explanation
    In a raster scan indicator, it takes two vertical scan periods to produce one complete picture. During the first scan period, the odd-numbered lines are drawn, and during the second scan period, the even-numbered lines are drawn. This process is repeated continuously to create a complete image on the screen.

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  • 24. 

    Which indicator component produces signals that determine the overall operation of what the indicator will do?

    • A.

      Data processing circuits

    • B.

      Deflection circuits

    • C.

      Cathode-ray tube

    • D.

      Video circuits

    Correct Answer
    A. Data processing circuits
    Explanation
    Data processing circuits are responsible for producing signals that determine the overall operation of an indicator. These circuits process the input data and generate the appropriate signals to control the indicator's behavior. They play a crucial role in interpreting and manipulating the data to produce meaningful output. Deflection circuits, cathode-ray tubes, and video circuits may be components of an indicator system, but they do not directly determine the overall operation of the indicator.

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  • 25. 

    In a typical indicator system, where is digital display data from the data processing circuits converted into analog drive signals?

    • A.

      Deflection circuits

    • B.

      Cathode-ray tube

    • C.

      Video circuits

    • D.

      Power supply

    Correct Answer
    A. Deflection circuits
    Explanation
    In a typical indicator system, the digital display data from the data processing circuits is converted into analog drive signals in the deflection circuits. These circuits are responsible for controlling the movement of the indicator, such as the position of a pointer or the deflection of a cathode-ray tube. By converting the digital data into analog signals in the deflection circuits, the indicator can accurately represent the information being processed by the system.

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  • 26. 

    The vacuum in a cathode-ray tube (CRT)

    • A.

      Prevents implosion if the CRT is broken

    • B.

      Keeps the phosphor coating from burning

    • C.

      Eliminates static charges on the deflection plates

    • D.

      Prevents collisions between electrons in the beam and air molecules

    Correct Answer
    D. Prevents collisions between electrons in the beam and air molecules
    Explanation
    The vacuum in a cathode-ray tube (CRT) prevents collisions between electrons in the beam and air molecules. In a CRT, an electron beam is generated and accelerated towards a phosphor-coated screen. If there was no vacuum inside the tube, the electrons in the beam would collide with air molecules, causing scattering and loss of focus. The vacuum ensures that there are no air molecules present to interfere with the path of the electron beam, allowing for accurate and precise display on the screen.

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  • 27. 

    What frequency is used for identification friend or foe/selective identification feature (IFF/SIF) interrogations?

    • A.

      1030 MHz

    • B.

      1070 MHz

    • C.

      1090 MHz

    • D.

      1270 MHz

    Correct Answer
    A. 1030 MHz
    Explanation
    The frequency used for Identification Friend or Foe/Selective Identification Feature (IFF/SIF) interrogations is 1030 MHz. This frequency is commonly used in aviation for radar systems to determine the identity of aircraft. By transmitting a signal at this frequency and receiving a response from an aircraft's transponder, the system can identify whether the aircraft is friendly or hostile.

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  • 28. 

    An X pulse is present in a selective identification feature code train when

    • A.

      A Mode 4 reply is being received

    • B.

      The aircraft is a pilotless drone or missile

    • C.

      The aircraft is declaring a military emergency

    • D.

      It is requested by the radar operator to identify the aircraft position

    Correct Answer
    B. The aircraft is a pilotless drone or missile
    Explanation
    The correct answer is "the aircraft is a pilotless drone or missile". This is because the presence of an X pulse in a selective identification feature code train is used to indicate that the aircraft is a pilotless drone or missile.

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  • 29. 

    Which selective identification feature special response explains a 7500 reply?

    • A.

      Communication failure

    • B.

      Military emergency

    • C.

      Engine failure

    • D.

      Hijacking

    Correct Answer
    D. Hijacking
    Explanation
    The special response "Hijacking" explains a 7500 reply. This means that the aircraft is being hijacked or is under the threat of hijacking. A 7500 reply is a code used in aviation to indicate a hijacking situation.

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  • 30. 

    What is the AN/UPM–155 radar test set capable of testing?

    • A.

      Interrogators and associated components

    • B.

      Radar antenna orientation

    • C.

      Radar jamming strength

    • D.

      Radar receivers

    Correct Answer
    A. Interrogators and associated components
    Explanation
    The AN/UPM-155 radar test set is capable of testing interrogators and associated components. It is used to assess the functionality and performance of these systems, ensuring that they are operating correctly and effectively. This test set is specifically designed for radar systems and is not capable of testing radar antenna orientation, radar jamming strength, or radar receivers.

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  • 31. 

    What possible input voltage(s) may be supplied to the AN/UPM–155 radar test set for operation?

    • A.

      115 Vac

    • B.

      120 Vac

    • C.

      230 vac

    • D.

      115 Vac or 230 Vac

    Correct Answer
    D. 115 Vac or 230 Vac
    Explanation
    The AN/UPM-155 radar test set can be operated with either a 115 Vac or a 230 Vac input voltage. This means that it can be supplied with either 115 Vac or 230 Vac for its operation.

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  • 32. 

    What element of modulation prevents interference when sharing the same communications path is necessary?

    • A.

      Spectrum conservation

    • B.

      Channel allocation

    • C.

      Ease of radiation

    • D.

      Companding

    Correct Answer
    B. Channel allocation
    Explanation
    Channel allocation is the element of modulation that prevents interference when sharing the same communications path. By allocating different channels to different users or devices, it ensures that their signals do not overlap and cause interference. This allows for efficient and reliable communication by minimizing the chances of signal degradation or loss due to interference.

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  • 33. 

    What factor determines the spacing of the sidebands in an amplitude modulated signal?

    • A.

      Amplitude of the modulating signal

    • B.

      Frequency of the modulating signal

    • C.

      Amplitude of the carrier signal

    • D.

      Frequency of the carrier signal

    Correct Answer
    B. Frequency of the modulating signal
    Explanation
    The spacing of the sidebands in an amplitude modulated signal is determined by the frequency of the modulating signal. In amplitude modulation, the modulating signal is superimposed onto the carrier signal, resulting in the creation of sidebands. These sidebands are located on either side of the carrier frequency, and their spacing is directly proportional to the frequency of the modulating signal. Therefore, a higher frequency modulating signal will result in sidebands that are spaced closer together, while a lower frequency modulating signal will result in sidebands that are spaced further apart.

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  • 34. 

    What is the relationship of the bandwidth required for double-sideband emitted carrier (DSBEC) amplitude modulation (AM) to the bandwidth of the modulating signal of the AM bandwidth alone?

    • A.

      One-quarter of the modulating bandwidth

    • B.

      Four times the modulating bandwidth

    • C.

      Twice the modulating bandwidth

    • D.

      Half the modulating bandwidth

    Correct Answer
    C. Twice the modulating bandwidth
    Explanation
    The bandwidth required for double-sideband emitted carrier (DSBEC) amplitude modulation (AM) is twice the bandwidth of the modulating signal. This means that the bandwidth needed to transmit the modulated signal is double the bandwidth of the original signal that is being modulated. This is because the DSBEC AM technique requires both the upper and lower sidebands of the modulated signal to be transmitted, resulting in a wider bandwidth requirement.

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  • 35. 

    In frequency modulation, the amount of oscillator frequency change is

    • A.

      Inversely proportional to the amplitude of the modulating signal

    • B.

      Directly proportional to the amplitude of the modulating signal

    • C.

      Inversely proportional to the phase of the modulating signal

    • D.

      Directly proportional to the phase of the modulating signal

    Correct Answer
    B. Directly proportional to the amplitude of the modulating signal
    Explanation
    In frequency modulation, the amount of oscillator frequency change is directly proportional to the amplitude of the modulating signal. This means that as the amplitude of the modulating signal increases, the frequency change of the oscillator also increases. This is because frequency modulation involves varying the frequency of the carrier signal based on the amplitude of the modulating signal. Therefore, a larger amplitude modulating signal will result in a larger frequency change in the carrier signal.

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  • 36. 

    A 10 kHz modulating signal has enough peak voltage to cause a deviation of 30 kHz. What is the modulation index?

    • A.

      5

    • B.

      0.5

    • C.

      0.3

    • D.

      3

    Correct Answer
    D. 3
    Explanation
    The modulation index is a measure of the extent of modulation in a signal. In this question, the modulating signal has a frequency of 10 kHz and causes a deviation of 30 kHz. The modulation index can be calculated by dividing the peak frequency deviation by the modulating signal frequency. In this case, 30 kHz divided by 10 kHz equals 3, which is the modulation index.

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  • 37. 

    In phase modulation, the carrier’s

    • A.

      Phase shifts at the rate of the modulating signal

    • B.

      Phase shifts with the phase of the modulating signal

    • C.

      Amplitude shifts at the rate of the modulating signal

    • D.

      Amplitude shifts with the phase of the modulating signal

    Correct Answer
    A. Phase shifts at the rate of the modulating signal
    Explanation
    In phase modulation, the phase of the carrier signal shifts at the same rate as the modulating signal. This means that as the modulating signal changes, the phase of the carrier signal also changes accordingly. The amplitude of the carrier signal remains constant in phase modulation, and it is the phase that is altered. This allows for the encoding of information in the phase of the signal, making phase modulation useful in communication systems where the phase of the signal carries the desired information.

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  • 38. 

    Information capacity is increased by how many times its normal rate if using 8– phase shift keying (PSK) instead of binary PSK?

    • A.

      Two

    • B.

      Three

    • C.

      Four

    • D.

      Five

    Correct Answer
    B. Three
    Explanation
    Using 8-phase shift keying (PSK) instead of binary PSK increases the information capacity by three times its normal rate. This is because binary PSK can transmit one bit per symbol, while 8-PSK can transmit three bits per symbol. Therefore, by increasing the number of phases, more information can be encoded and transmitted in each symbol, resulting in a higher information capacity.

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  • 39. 

    What size bit combinations are allowed when using 16–phase shift keying?

    • A.

      2 bit

    • B.

      3 bit

    • C.

      4 bit

    • D.

      5 bit

    Correct Answer
    C. 4 bit
    Explanation
    16-phase shift keying allows for 4-bit combinations. This means that each symbol in the transmission can represent 4 bits of information. With 4 bits, there are a total of 16 possible combinations, which aligns with the 16-phase shift keying technique.

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  • 40. 

    What part of the pulse code modulation process converts a continuous time signal into a discrete time signal?

    • A.

      Sampling

    • B.

      Rectifying

    • C.

      Oscillating

    • D.

      Band Limiting

    Correct Answer
    A. Sampling
    Explanation
    Sampling is the part of the pulse code modulation process that converts a continuous time signal into a discrete time signal. In this process, the continuous time signal is sampled at regular intervals, and each sample represents the amplitude of the signal at that particular instant. By converting the continuous signal into discrete samples, it becomes easier to process and transmit the signal digitally.

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  • 41. 

    By how much does non-uniform quantizing and companding decreases the length of a code word?

    • A.

      11 to 7 bits

    • B.

      11 to 8 bits

    • C.

      16 to 7 bits

    • D.

      16 to 8 bits

    Correct Answer
    A. 11 to 7 bits
    Explanation
    Non-uniform quantizing and companding decreases the length of a code word from 11 bits to 7 bits. This means that the process of non-uniform quantizing and companding reduces the number of bits required to represent a signal, resulting in a more efficient and compressed representation of the data.

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  • 42. 

    How is the parity bit used in asynchronous transmission?

    • A.

      By the receiving device to verify that the transmission was received correctly

    • B.

      By the transmitting device to verify that the transmission was transmitted correctly

    • C.

      By the modulator device to verify that the intelligence signal was received correctly

    • D.

      By the band limiting device to verify that the output signal was transmitted correctly

    Correct Answer
    A. By the receiving device to verify that the transmission was received correctly
    Explanation
    The parity bit is used by the receiving device to verify that the transmission was received correctly. The parity bit is an extra bit added to a binary code to detect errors during transmission. The transmitting device calculates the parity bit based on the data being sent and adds it to the transmission. The receiving device then recalculates the parity bit based on the received data and compares it to the transmitted parity bit. If they match, it indicates that the transmission was received correctly. If they don't match, it suggests that an error occurred during transmission.

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  • 43. 

    How does synchronous transmission reduce the overhead costs of data transmission?

    • A.

      Communicates in parallel format

    • B.

      Blocks many characters together for transmission

    • C.

      Eliminates the control bits, so more message data can be sent

    • D.

      Uses low cost equipment to support synchronous transmission

    Correct Answer
    B. Blocks many characters together for transmission
    Explanation
    Synchronous transmission reduces the overhead costs of data transmission by blocking many characters together for transmission. This means that multiple characters are sent as a single unit, reducing the number of individual transmissions required and therefore reducing the associated overhead costs. By sending multiple characters together, the transmission process becomes more efficient and cost-effective.

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  • 44. 

    During a vertical redundancy check, what significance does the amount of 1’s have in a data 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
    Explanation
    The amount of 1's in a data bit pattern during a vertical redundancy check determines the parity. Parity is a method used to detect errors in data transmission. It involves adding an extra bit to the data, which is set to 1 or 0 in such a way that the total number of 1's in the data, including the extra bit, is always even or odd. By comparing the received data with the expected parity, errors can be detected.

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  • 45. 

    Using the longitudinal redundancy check method of error correction, what does the receiver compare with the transmitter to ensure an accurate transmission of data?

    • A.

      The checksum

    • B.

      Block check character

    • C.

      The ASCII character set

    • D.

      The sum of transmitted bits

    Correct Answer
    B. Block check character
    Explanation
    The receiver compares the block check character with the transmitter to ensure an accurate transmission of data. The block check character is a form of error detection code that is added to the data being transmitted. By comparing the block check character received with the one generated by the transmitter, the receiver can determine if any errors have occurred during transmission. This helps ensure the integrity and accuracy of the transmitted data.

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  • 46. 

    When used together, what two error detection methods are 98 percent effective in detecting errors?

    • A.

      Checksum and cyclic redundancy check

    • B.

      Longitudinal redundancy check and checksum

    • C.

      Cyclic redundancy check and vertical redundancy check

    • D.

      Vertical redundancy check and longitudinal redundancy check

    Correct Answer
    D. Vertical redundancy check and longitudinal redundancy check
  • 47. 

    What error detection method is used for checking a data block greater than 512 and is about 99 percent effective in most applications?

    • A.

      Checksum

    • B.

      Cyclic redundancy

    • C.

      Vertical redundancy

    • D.

      Longitudinal redundancy

    Correct Answer
    B. Cyclic redundancy
    Explanation
    Cyclic redundancy is an error detection method used for checking data blocks greater than 512 and is about 99 percent effective in most applications. It involves generating a short check value, or checksum, from the data and appending it to the data block. When the data is received, the checksum is recalculated and compared to the received checksum. If they match, it is assumed that the data was transmitted correctly. If they do not match, it indicates that an error has occurred during transmission.

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  • 48. 

    When using forward error control as a method of error correction, where does error correction take place?

    • A.

      Receiving end

    • B.

      In the oscillator

    • C.

      Transmitting end

    • D.

      In the primary buffers

    Correct Answer
    A. Receiving end
    Explanation
    Error correction takes place at the receiving end when using forward error control as a method of error correction. This means that the errors in the transmitted data are detected and corrected at the destination or receiver of the data. The receiving end analyzes the received data and applies the necessary error correction techniques to ensure the accuracy and integrity of the transmitted information.

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  • 49. 

    Which statement describes an advantage of using fiber optic cable?

    • A.

      The easy tap-ability of fiber optic cables reduces security risks

    • B.

      Fiber optic cable has a higher attenuation than coaxial cable

    • C.

      Electromagnetic fields do not affect fiber optic cables

    • D.

      Nuclear radiation does not affect fiber optic cable

    Correct Answer
    C. Electromagnetic fields do not affect fiber optic cables
    Explanation
    Fiber optic cables are not affected by electromagnetic fields, which is an advantage over other types of cables. Electromagnetic interference can disrupt the signal transmission in traditional copper cables, leading to signal degradation and data loss. However, fiber optic cables use light signals instead of electrical signals, making them immune to electromagnetic interference. This allows for more reliable and secure data transmission, especially in environments with high electromagnetic activity such as power plants or industrial facilities.

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  • 50. 

    Which statement describes a security feature of using fiber optic cable?

    • A.

      Easy to encrypt data

    • B.

      Low signal attenuation

    • C.

      Virtually impossible to tap a fiber optic cable unnoticed

    • D.

      Fiber optic cables are considerably smaller than metallic cable

    Correct Answer
    C. Virtually impossible to tap a fiber optic cable unnoticed
    Explanation
    Fiber optic cables are virtually impossible to tap unnoticed because they do not emit any electromagnetic signals that can be intercepted. Unlike traditional metallic cables, fiber optic cables use light to transmit data, making it extremely difficult for hackers to tap into the cable without being detected. This provides a high level of security for transmitting sensitive information.

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Quiz Review Timeline +

Our quizzes are rigorously reviewed, monitored and continuously updated by our expert board to maintain accuracy, relevance, and timeliness.

  • Current Version
  • Mar 21, 2023
    Quiz Edited by
    ProProfs Editorial Team
  • Jul 03, 2012
    Quiz Created by
    Huroku
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