3D1X3 Vol 1 CDC Ed 2

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Quizzes Created: 4 | Total Attempts: 1,039

Questions: 100 | Attempts: 201 | Updated: Mar 21, 2023

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3d1x3 Vol 1 CDC Ed 2

Questions and Answers

1.

(001) What is one reason for modulation that involves modulatiing low frequency signals for transmission over long distances?
- A.
  
  Spectrum Conservation
- B.
  
  Channel allocation
- C.
  
  Ease of radiation
- D.
  
  Companding
Correct Answer
C. Ease of radiation

Explanation
Modulating low frequency signals for transmission over long distances allows for ease of radiation. This means that the modulated signal can be easily transmitted and propagated through the air or other medium without significant loss or degradation. By modulating the low frequency signals, they can be converted into higher frequency signals that are more suitable for long distance transmission. This process makes it easier to transmit the signals over long distances without the need for complex and expensive equipment.

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2.

(001) What are the three general categories used to produce modulation in radio frequency (RF) transmission today?
- A.
  
  Binary amplitude shift keying, frequency shift keying, and phase shift keying.
- B.
  
  Pulse amplitude, pulse width, and pulse position.
- C.
  
  Amplitude, frequency, and phase.
- D.
  
  Analog, digital and shift keying.
Correct Answer
C. Amplitude, frequency, and pHase.

Explanation
The correct answer is amplitude, frequency, and phase. These three general categories are used to produce modulation in radio frequency transmission today. Amplitude modulation (AM) involves varying the strength of the radio wave to carry information. Frequency modulation (FM) involves varying the frequency of the radio wave. Phase modulation (PM) involves varying the phase of the radio wave. These modulation techniques allow for the encoding and decoding of information in radio frequency transmission.

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3.

(002) When the modulating signal and carrier signal are combined within a modulator, the output signal contains
- A.
  
  Modulating signal, upper sideband, and lower sideband.
- B.
  
  Carrier, upper sideband, and lower sideband.
- C.
  
  Upper sideband and modulating signal.
- D.
  
  Carrier and modulating signal.
Correct Answer
B. Carrier, upper sideband, and lower sideband.

Explanation
When the modulating signal and carrier signal are combined within a modulator, the resulting output signal will contain the carrier signal as well as the upper and lower sidebands. The carrier signal is the original unmodulated signal, while the upper sideband represents the frequencies above the carrier frequency and the lower sideband represents the frequencies below the carrier frequency. Therefore, the correct answer is that the output signal contains the carrier, upper sideband, and lower sideband.

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4.

(002) If a carrier frequency of 1 MHz and a modulating tone of 10 kHz goes to the modulator, the output signal include
- A.
  
  1.01 MHz, 1 MHz, and 0.99 MHz.
- B.
  
  1.1 MHz, 1 MHz, and 0.9 MHz.
- C.
  
  1.11 MHz, 1 MHz, 0.99 MHz.
- D.
  
  1.111 MHz, 1 MHz, 0.999 MHz.
Correct Answer
A. 1.01 MHz, 1 MHz, and 0.99 MHz.

Explanation
When a carrier frequency of 1 MHz and a modulating tone of 10 kHz are input into the modulator, the output signal will include the carrier frequency (1 MHz), the sum of the carrier frequency and the modulating tone (1.01 MHz), and the difference between the carrier frequency and the modulating tone (0.99 MHz).

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5.

(002) The bandwidth of an amplitude modulated signal is
- A.
  
  Two times the modulating signal.
- B.
  
  The same as the modulating signal.
- C.
  
  Determined by the modulation index.
- D.
  
  Defined in terms of maximum amount of modulation.
Correct Answer
A. Two times the modulating signal.

Explanation
The bandwidth of an amplitude modulated signal is two times the modulating signal. This means that the range of frequencies needed to accurately represent the modulating signal is twice the highest frequency present in the modulating signal. This is because in amplitude modulation, the sidebands are located above and below the carrier frequency, and their width is equal to the highest frequency in the modulating signal. Therefore, the total bandwidth required to transmit the modulated signal is twice the modulating signal's bandwidth.

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6.

(002) Use the formula on page 1–3. If an oscilloscope displays a modulation envelope having an Emax of 200 volts and an Emin of 20 volts, what is the modulation percentage?
- A.
  
  81.8
- B.
  
  85.5
- C.
  
  88
- D.
  
  122
Correct Answer
A. 81.8

Explanation
The modulation percentage can be calculated using the formula: (Emax - Emin) / (Emax + Emin) * 100. In this case, the Emax is 200 volts and the Emin is 20 volts. Plugging these values into the formula, we get (200 - 20) / (200 + 20) * 100 = 180 / 220 * 100 = 81.8. Therefore, the modulation percentage is 81.8.

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7.

(002) Which statement concerning bandwidth is true?
- A.
  
  Overmodulating increases bandwidth because the distortion produces harmonics.
- B.
  
  Undermodulating increases bandwidth because the distortion produces harmonics.
- C.
  
  Overmodulating increases bandwidth because the output’s increased amplitude.
- D.
  
  Undermodulating increases bandwidth because the output’s decreased amplitude.
Correct Answer
A. Overmodulating increases bandwidth because the distortion produces harmonics.

Explanation
Overmodulating increases bandwidth because the distortion produces harmonics. When a signal is overmodulated, the amplitude of the signal exceeds the maximum limit, causing distortion. This distortion results in the creation of additional frequencies known as harmonics. These harmonics increase the overall bandwidth of the signal as they occupy additional frequency space. Therefore, overmodulating a signal leads to an increase in bandwidth due to the presence of harmonics.

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8.

(003) The output of the oscillator in a frequency modulation (FM) modulator increases in frequency with each
- A.
  
  Positive half cycle of the carrier.
- B.
  
  Negative half cycle of the carrier.
- C.
  
  Positive half cycle of the modulating signal.
- D.
  
  Negative half cycle of the modulating signal.
Correct Answer
A. Positive half cycle of the carrier.

Explanation
In frequency modulation (FM), the frequency of the output of the oscillator increases with each positive half cycle of the carrier signal. This means that as the carrier signal goes through its positive half cycle, the frequency of the output signal from the oscillator increases. This is a characteristic of FM modulation, where the frequency of the carrier signal is varied based on the amplitude of the modulating signal.

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9.

(003) In frequency modulation, a significant sideband contains at least what percentage of the total transmitted power?
- A.
  
  1
- B.
  
  3
- C.
  
  10
- D.
  
  0.1
Correct Answer
A. 1

Explanation
In frequency modulation, a significant sideband contains at least 1% of the total transmitted power.

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10.

(003) What is the formula to find the modulating index?
- A.
  
  Deviation divided by frequency of modulation.
- B.
  
  Deviation times frequency of modulation.
- C.
  
  Sideband divide by carrier frequency.
- D.
  
  Sideband times carrier frequency.
Correct Answer
A. Deviation divided by frequency of modulation.

Explanation
The formula to find the modulating index is deviation divided by frequency of modulation. This formula is used to calculate the extent of variation in the carrier wave caused by the modulating signal. The modulating index represents the ratio of the maximum frequency deviation to the frequency of the modulating signal. By dividing the deviation by the frequency of modulation, we can determine the modulating index and understand the degree of modulation in the carrier wave.

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11.

(003) A 5 kHz modulating signal has enough peak voltage to cause a deviation of 15 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 frequency deviation in a frequency modulation (FM) signal. It is calculated by dividing the peak frequency deviation by the modulating frequency. In this case, the modulating signal has a frequency of 5 kHz and causes a deviation of 15 kHz. Therefore, the modulation index is 15 kHz / 5 kHz = 3.

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12.

(003) What is it called when a narrow frequency band between adjacent stations prevent frequency modulated sidebands from overlapping?
- A.
  
  Space
- B.
  
  Guard Band
- C.
  
  Buffer zone
- D.
  
  Prevention field
Correct Answer
B. Guard Band

Explanation
A guard band is a narrow frequency band that is used to prevent frequency modulated sidebands from overlapping between adjacent stations. It acts as a buffer zone or prevention field to ensure that the signals do not interfere with each other. This helps to maintain the clarity and integrity of the transmitted signals and prevents any distortion or overlap that could occur if the frequencies were not properly separated.

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13.

(004) In phase modulation, what part of the carrier signal is varied?
- A.
  
  Frequency
- B.
  
  Amplitude
- C.
  
  Height
- D.
  
  Phase
Correct Answer
D. pHase

Explanation
In phase modulation, the part of the carrier signal that is varied is the phase. This means that the timing of the carrier signal is adjusted in order to encode the information being transmitted. By changing the phase of the carrier signal, different symbols or bits can be represented, allowing for the transmission of data.

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14.

(004) In phase modulation, the carrier’s
- A.
  
  Phase is shifted at the rate of the modulating signal.
- B.
  
  Phase shifted with the phase of the modulating signal.
- C.
  
  Amplitude is shifted at the rate of the modulating signal.
- D.
  
  Amplitude is shifted with the phase of the modulating signal.
Correct Answer
A. pHase is shifted at the rate of the modulating signal.

Explanation
In phase modulation, the phase of the carrier signal is shifted at the rate of the modulating signal. This means that the instantaneous phase of the carrier signal is varied according to the amplitude of the modulating signal. This allows for the transmission of information by encoding it in the changes in phase of the carrier signal.

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15.

(005) What is the first step in the pulse code modulation process?
- A.
  
  Discrete amplitudes are assigned to the sampling pulses.
- B.
  
  A binary code number is assigned to the sample.
- C.
  
  The quantizer limits the amplitude of the pulses.
- D.
  
  The analog signal is band limited.
Correct Answer
D. The analog signal is band limited.

Explanation
The first step in the pulse code modulation process is to band limit the analog signal. Band limiting refers to the process of restricting the frequency range of the analog signal to a specific range. This is done to ensure that the signal can be accurately represented and reconstructed using a digital code. By limiting the bandwidth of the analog signal, it becomes easier to sample and quantize the signal, which are subsequent steps in the pulse code modulation process.

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16.

(005) 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 to obtain a series of discrete samples. These samples represent the amplitude of the signal at specific points in time. Sampling is essential to convert analog signals into digital signals, which can be processed and transmitted more efficiently.

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17.

(006) In asynchronous transmissions, what bit is used by the receiving device to verify that the transmission was received correctly?
- A.
  
  Control
- B.
  
  Parity
- C.
  
  Start
- D.
  
  Stop
Correct Answer
B. Parity

Explanation
Parity is used in asynchronous transmissions to verify that the transmission was received correctly. Parity is a bit that is added to the data being transmitted. The receiving device checks the parity bit to ensure that the number of bits set to 1 in the data is either even or odd, depending on the type of parity being used. If the parity check fails, it indicates that there was an error in the transmission.

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18.

(006) If an error should occur, what transmission is lost in an synchronous transmission?
- A.
  
  One Character
- B.
  
  Block of data
- C.
  
  A parity bit
- D.
  
  A stop bit
Correct Answer
B. Block of data

Explanation
In synchronous transmission, data is sent in blocks rather than individual characters. Each block of data is transmitted as a single unit and is synchronized with the clock signal. If an error occurs during transmission, the entire block of data may be lost, resulting in the loss of multiple characters. Therefore, in synchronous transmission, the block of data is lost if an error occurs.

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19.

(007) When using vertical redundancy check, what significance does the amount of ones 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 ones in a data bit pattern determines the parity. Parity is a form of error checking where an extra bit is added to a data transmission to ensure that the number of ones in the transmission is always even or odd. By checking the parity bit, the receiver can detect if any errors occurred during transmission.

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20.

(007) What error detection method is used for checking a data block greater than 512 and is about 99percent effective in most applications?
- A.
  
  Checksum.
- B.
  
  Cyclic redundancy check
- C.
  
  Vertical redundancy check.
- D.
  
  Longitudinal redundancy check.
Correct Answer
B. Cyclic redundancy check

Explanation
Cyclic redundancy check (CRC) is an error detection method used for checking a data block greater than 512 and is about 99% effective in most applications. CRC involves generating a checksum by performing mathematical calculations on the data block, which is then compared with the checksum received at the receiving end. If the checksums match, it is highly likely that the data block was transmitted without errors. CRC is widely used in various communication protocols and storage systems to ensure data integrity.

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21.

(007) 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 are detected and corrected after the data has been transmitted and received by the intended recipient. The receiving end is responsible for identifying any errors in the received data and applying the necessary corrections to ensure the accuracy and integrity of the transmitted information.

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22.

(008) Light sources that are applicable to fiber optic waveguide are light-emitting diodes and
- A.
  
  Photo transistors.
- B.
  
  Hybrid photodiodes.
- C.
  
  Semiconductor laser diodes.
- D.
  
  Integrated photodiode/preamplifiers.
Correct Answer
C. Semiconductor laser diodes.

Explanation
Semiconductor laser diodes are applicable to fiber optic waveguides because they can generate coherent light with a narrow beam divergence. This makes them suitable for transmitting light signals over long distances through the fiber optic cables. Light-emitting diodes (LEDs) can also be used, but they are less efficient and have a wider beam divergence. Photo transistors and integrated photodiode/preamplifiers are used for detecting the light signals in the fiber optic system, but they are not used as the light source. Hybrid photodiodes are not commonly used in fiber optic waveguides.

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23.

(008) What type of light is emitted from a laser?
- A.
  
  Incoherent.
- B.
  
  Coherent.
- C.
  
  Ordinary.
- D.
  
  Invisible.
Correct Answer
B. Coherent.

Explanation
A laser emits coherent light. Coherent light is characterized by its uniformity in wavelength and phase, meaning that all the light waves are in sync and have a consistent frequency. This is achieved through a process called stimulated emission, where photons are released in a controlled manner. Unlike ordinary light sources, such as a light bulb, which emit incoherent light with various wavelengths and phases, a laser produces a narrow, focused beam of light that is highly concentrated and can travel long distances without significant spreading or divergence.

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24.

(009) What are the two main types of photodetectors?
- A.
  
  Positive intrinsic negative and avalanche photodiode.
- B.
  
  Light-emitting diode and avalanche photodiode.
- C.
  
  Light emitting diode and semiconductor laser.
- D.
  
  Tunnel and zener diodes.
Correct Answer
A. Positive intrinsic negative and avalanche pHotodiode.

Explanation
The correct answer is positive intrinsic negative and avalanche photodiode. These are the two main types of photodetectors used in various applications. Positive intrinsic negative (PIN) photodiodes are widely used for low-light-level detection and have a high responsivity. Avalanche photodiodes (APD) are used for high-speed and high-gain applications, as they can generate an internal avalanche gain. Both types of photodetectors are essential in different scenarios depending on the required sensitivity and speed of detection.

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25.

(009) What photo detector converts one photon to one electron?
- A.
  
  Light emitting diode.
- B.
  
  Avalanche photodiode.
- C.
  
  Positive intrinsic negative diode.
- D.
  
  Integrated photodiode/preamplifier.
Correct Answer
C. Positive intrinsic negative diode.

Explanation
The correct answer is Positive intrinsic negative diode because this type of diode, also known as PIN diode, is capable of converting one photon to one electron. It has a heavily doped P region and a heavily doped N region, with an intrinsic region in between. When a photon is absorbed by the intrinsic region, it creates an electron-hole pair, and the electric field in the diode causes the electron to move towards the N region, resulting in the conversion of one photon to one electron.

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26.

(010) Which repeater amplifies optical signal without converting to and from the electrical domain?
- A.
  
  Receiver.
- B.
  
  Repeaters.
- C.
  
  Regenerators.
- D.
  
  Optical amplifiers.
Correct Answer
D. Optical amplifiers.

Explanation
Optical amplifiers are devices that amplify optical signals directly without converting them to electrical signals. Unlike repeaters, which regenerate and amplify electrical signals, optical amplifiers work in the optical domain, amplifying the signal without the need for conversion. Therefore, optical amplifiers are the correct answer for this question.

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27.

(011) A short section of single fiber cable that has a connector at each end is called a
- A.
  
  Pigtail
- B.
  
  Jumper
- C.
  
  Patch cord
- D.
  
  Breakout cables
Correct Answer
C. Patch cord

Explanation
A short section of single fiber cable that has a connector at each end is called a patch cord. A patch cord is used to connect devices or components in a network or telecommunications system. It allows for easy and quick connections between devices without the need for splicing or permanent installations. Patch cords are commonly used in data centers, telecommunications rooms, and other networking environments to establish temporary or permanent connections between devices.

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28.

(011) Which fiber-optic connector uses quick-release, keyed bayonet couplings that are preferred in situations where severe vibrations are not expected?
- A.
  
  Biconic.
- B.
  
  Field (FC).
- C.
  
  Straight tip (ST).
- D.
  
  Sub-miniature, type A (SMA).
Correct Answer
C. Straight tip (ST).

Explanation
The straight tip (ST) fiber-optic connector uses quick-release, keyed bayonet couplings that are preferred in situations where severe vibrations are not expected. This means that the ST connector is designed to provide a secure and stable connection while still being easy to install and remove. The quick-release feature allows for quick and convenient installation and removal, while the keyed bayonet couplings ensure a secure and reliable connection. This makes the ST connector a suitable choice for applications where vibrations are not a concern.

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29.

___________ close your mouth.
- A.
  
  Mastro
- B.
  
  Scholten
- C.
  
  Kirk
- D.
  
  Feeley
Correct Answer
A. Mastro
30.

(012) High-altitude electromagnetic pulse is a wideband phenomenon that involves which frequency range?
- A.
  
  1 hertz to 1 kilohertz.
- B.
  
  1 hertz to 1 gigahertz.
- C.
  
  10 hertz to 10 kilohertz.
- D.
  
  10 hertz to 10 gigahertz.
Correct Answer
B. 1 hertz to 1 gigahertz.

Explanation
High-altitude electromagnetic pulse (HEMP) is a phenomenon that occurs when a nuclear explosion happens at high altitudes, creating a burst of electromagnetic radiation. HEMP is a wideband phenomenon, meaning it covers a wide range of frequencies. The correct answer, 1 hertz to 1 gigahertz, reflects the frequency range in which HEMP occurs. This range includes both low frequencies (1 hertz) and high frequencies (1 gigahertz), encompassing a broad spectrum of electromagnetic radiation.

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31.

(012) A system-generated electromagnetic pulse is a problem for satellites and reentry vehicles that are
- A.
  
  Susceptible to the wideband frequency phenomenon.
- B.
  
  Directly exposed to nuclear radiations from a high-altitude burst.
- C.
  
  Affected by the azimuthal magnetic fields and time-varying air conductivity.
- D.
  
  Influenced by the signal fading or waveform distortion caused by the structured plasma field.
Correct Answer
B. Directly exposed to nuclear radiations from a high-altitude burst.

Explanation
Satellites and reentry vehicles can be affected by a system-generated electromagnetic pulse if they are directly exposed to nuclear radiations from a high-altitude burst. This means that if these vehicles are in close proximity to a high-altitude nuclear explosion, the resulting radiation can cause disruptions to their systems. This is because the electromagnetic pulse generated by the explosion can interfere with the electronics and communication systems of these vehicles, potentially causing malfunctions or damage.

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32.

(012) High-altitude electromagnetic pulse environment protection is important for critical, time urgent mission systems because it
- A.
  
  Is a problem for electronic components in satellites and reentry vehicles.
- B.
  
  Has a vertical amplitude that decreases inversely with distance, but remains significant for many kilometers.
- C.
  
  Has very intense radial electrical fields, azimuthal magnetic fields, and time-varying air conductivity.
- D.
  
  Is the only nuclear environment that may be imposed on many systems simultaneously with the expenditure of very few weapons.
Correct Answer
D. Is the only nuclear environment that may be imposed on many systems simultaneously with the expenditure of very few weapons.

Explanation
The given correct answer states that high-altitude electromagnetic pulse (HEMP) is the only nuclear environment that can affect many systems at once with only a few weapons. This means that HEMP has the potential to disrupt a large number of critical, time-urgent mission systems simultaneously, making it crucial to protect against its effects. The other options mentioned in the question, such as the problem for electronic components in satellites and reentry vehicles, the vertical amplitude decreasing inversely with distance, and the intense radial electrical fields and time-varying air conductivity of HEMP, are not the main reasons why HEMP protection is important for critical mission systems.

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33.

(012) Which distinct region of the source region electromagnetic pulse is produced by the interactions between the weapon products and the earth’s atmosphere?
- A.
  
  Secondary.
- B.
  
  Radiated.
- C.
  
  Plasma.
- D.
  
  Source
Correct Answer
D. Source

Explanation
The correct answer is "Source." The source region of the electromagnetic pulse (EMP) is where the EMP is initially produced. It is the distinct region where the interactions between the weapon products and the earth's atmosphere occur, resulting in the generation of the EMP.

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34.

(012) Atmospheric disturbances from initial nuclear radiation on higher frequencies affect communications by
- A.
  
  Blackout effects.
- B.
  
  Absorption effects.
- C.
  
  Scintillation effects.
- D.
  
  Attenuation effects.
Correct Answer
C. Scintillation effects.

Explanation
Scintillation effects refer to the rapid fluctuations in the amplitude and phase of radio waves caused by atmospheric disturbances. These disturbances, which are a result of initial nuclear radiation, can cause signal fading and interruptions in communication systems. Therefore, scintillation effects are the most likely explanation for how atmospheric disturbances from initial nuclear radiation affect communications.

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35.

(013) Currents and voltages induced on power lines, cable links, and pipelines by electromagnetic pulse are called
- A.
  
  Scintillation.
- B.
  
  Local effects.
- C.
  
  Source region.
- D.
  
  Long-line effects.
Correct Answer
D. Long-line effects.

Explanation
The currents and voltages induced on power lines, cable links, and pipelines by electromagnetic pulses are referred to as "long-line effects." This term is used to describe the phenomenon where the electromagnetic pulse causes disturbances and fluctuations in the electrical and magnetic fields along the entire length of the power lines, cables, and pipelines. These effects can lead to damage or disruption of the infrastructure and can have significant impacts on the operation of electrical and communication systems.

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36.

(013) Which type of filters are always used in combination with surge arresters?
- A.
  
  Linear
- B.
  
  AC line.
- C.
  
  DC line.
- D.
  
  Power line.
Correct Answer
A. Linear

Explanation
Surge arresters are used to protect electrical systems from voltage spikes or surges. Linear filters are always used in combination with surge arresters to filter out any high-frequency noise or harmonics that may be present in the system. This ensures that the electrical equipment is protected from both voltage surges and unwanted electrical disturbances. AC line, DC line, and power line filters may also be used in certain applications, but linear filters are always used in combination with surge arresters.

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37.

(014) If the interference can be eliminated by disconnecting the receiving antenna, the source of the disturbance is most likely
- A.
  
  Line noise.
- B.
  
  Internal to the radio.
- C.
  
  External to the radio.
- D.
  
  Radio receiver trouble.
Correct Answer
C. External to the radio.

Explanation
If disconnecting the receiving antenna eliminates the interference, it suggests that the source of the disturbance is external to the radio. This means that the interference is coming from an external source, such as another electronic device or a nearby power line, rather than being caused by a fault within the radio itself.

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38.

(014) Little or no variations in the strength of the interfering signal when moving the receiving antenna for short distance normally indicates
- A.
  
  Enemy jamming.
- B.
  
  Internal interference.
- C.
  
  Radio receiver trouble.
- D.
  
  Unintentional interference.
Correct Answer
A. Enemy jamming.

Explanation
Little or no variations in the strength of the interfering signal when moving the receiving antenna for a short distance normally indicates enemy jamming. This means that the interfering signal remains constant regardless of the movement of the antenna, suggesting that it is intentionally being transmitted to disrupt or interfere with the communication. This is different from internal interference, which would likely vary in strength as the antenna is moved. Radio receiver trouble would also result in inconsistent signal strength, and unintentional interference would not necessarily remain constant when the antenna is moved.

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39.

(014) What type of electromagnetic interference occurs when a receiver responds to off-frequency signals?
- A.
  
  Rusty bolt.
- B.
  
  Co-channel.
- C.
  
  Brute force.
- D.
  
  Spurious responses.
Correct Answer
D. Spurious responses.

Explanation
Spurious responses refer to the occurrence of a receiver responding to off-frequency signals. This type of electromagnetic interference can cause unintended responses or disruptions in the receiver's operation.

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40.

(014) Which type of intermodulation interference varies significantly with temperature and weather conditions?
- A.
  
  Transmitter.
- B.
  
  Rusty-bolt.
- C.
  
  Spurious
- D.
  
  Receiver.
Correct Answer
B. Rusty-bolt.

Explanation
Rusty-bolt interference is a type of intermodulation interference that is caused by the presence of rusty or corroded metal objects in the vicinity of the radio communication system. This type of interference can vary significantly with temperature and weather conditions because these factors can affect the conductivity and resistance of the rusty metal, leading to changes in the level of interference.

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41.

(014) How can you normally eliminate electromagnetic interference noise bursts caused by sodium and mercury vapor lights that have stopped working while the power is still applied?
- A.
  
  Change the bulb.
- B.
  
  Ground out the light fixture.
- C.
  
  Install a noise reject filter on the light.
- D.
  
  Install a noise reject filter on the receiver.
Correct Answer
A. Change the bulb.

Explanation
Sodium and mercury vapor lights can emit electromagnetic interference when they are not functioning properly. This interference can cause noise bursts in electronic devices. By changing the bulb, the issue can be resolved as a faulty bulb may be the cause of the interference.

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42.

What man-made noise results from voltage surges, arcing, or corona discharges?
- A.
  
  Relays.
- B.
  
  Lighting.
- C.
  
  Power line.
- D.
  
  Switching equipment.
Correct Answer
C. Power line.

Explanation
Voltage surges, arcing, and corona discharges can cause disturbances in power lines, resulting in man-made noise. This noise can be generated due to the fluctuations in voltage, the arcing of electricity, or the corona discharges occurring along the power line. Therefore, the correct answer is power line.

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43.

(015) What Air Force program is used to resolve an electromagnetic interference incident?
- A.
  
  Mishap prevention.
- B.
  
  Frequency management.
- C.
  
  Electrostatic discharge control.
- D.
  
  Spectrum interference resolution.
Correct Answer
D. Spectrum interference resolution.

Explanation
The correct answer is Spectrum interference resolution. This program is used by the Air Force to resolve incidents of electromagnetic interference. It helps in identifying and resolving issues related to spectrum interference, which can disrupt communication and other electronic systems. By using this program, the Air Force can effectively manage and mitigate any interference that may occur, ensuring the smooth operation of their equipment and systems.

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44.

(015) At what level does the Air Force want electromagnetic interference problems resolved?
- A.
  
  Affected unit.
- B.
  
  Affected major command.
- C.
  
  Electromagnetic environmental effects office.
- D.
  
  Spectrum interference resolution office.
Correct Answer
A. Affected unit.

Explanation
The Air Force wants electromagnetic interference problems to be resolved at the level of the affected unit. This means that the responsibility for resolving these problems lies with the specific unit that is experiencing the interference. It is important for the affected unit to address and resolve these issues in order to ensure proper functioning of their equipment and operations.

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45.

(015) What do you do when you are reasonably sure electromagnetic interference exists?
- A.
  
  Request engineering assistance.
- B.
  
  Contact the base frequency manager.
- C.
  
  Systematically gather data for analysis.
- D.
  
  Contact the spectrum interference resolution office.
Correct Answer
C. Systematically gather data for analysis.

Explanation
When you are reasonably sure electromagnetic interference exists, the best course of action is to systematically gather data for analysis. This involves collecting information about the interference, such as its frequency, intensity, and duration, in order to better understand its source and potential impact on the system. This data can then be analyzed to determine the appropriate steps to mitigate or resolve the interference. Requesting engineering assistance or contacting the base frequency manager or spectrum interference resolution office may be necessary at a later stage, but the initial step is to gather data for analysis.

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46.

(015) Who is initially responsible for reporting an electromagnetic interference?
- A.
  
  The operator.
- B.
  
  Major command.
- C.
  
  The frequency manager.
- D.
  
  Federal Communications Commission.
Correct Answer
A. The operator.

Explanation
The operator is initially responsible for reporting an electromagnetic interference. This means that it is the operator's duty to identify and report any instances of electromagnetic interference that may occur. The operator plays a crucial role in ensuring that any interference is promptly reported and addressed, as they are the first line of defense in maintaining the integrity and effectiveness of the electromagnetic spectrum.

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47.

(015) Who is tasked to provide interference resolution support to the unified commanders?
- A.
  
  The operator.
- B.
  
  Joint spectrum center.
- C.
  
  Installation spectrum manager.
- D.
  
  Federal Communications Commission.
Correct Answer
B. Joint spectrum center.

Explanation
The correct answer is the Joint spectrum center. The Joint spectrum center is responsible for providing interference resolution support to the unified commanders. They coordinate and manage the electromagnetic spectrum for military operations, ensuring that different systems and devices can operate without interference. They work closely with the operators and installation spectrum managers to identify and resolve any interference issues that may arise. The Federal Communications Commission also plays a role in managing the electromagnetic spectrum, but their primary focus is on civilian communications and not specifically on providing interference resolution support to the unified commanders.

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48.

(016) Which feature of the Fluke 8025A multimeter do you use to select various measurement functions?
- A.
  
  Circuit jacks.
- B.
  
  Rotary switch.
- C.
  
  Range push button.
- D.
  
  Touch-hold button.
Correct Answer
B. Rotary switch.

Explanation
The rotary switch is the feature of the Fluke 8025A multimeter that allows you to select various measurement functions. The rotary switch is a dial that can be turned to different positions, each corresponding to a specific measurement function such as voltage, current, resistance, or continuity. By rotating the switch to the desired function, you can easily select and switch between different measurement modes on the multimeter.

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49.

(016) Which part of the Fluke 8025A’s display section indicates the absolute value of the input?
- A.
  
  Digital.
- B.
  
  Annunciator.
- C.
  
  Range indicator.
- D.
  
  Analog bar graph.
Correct Answer
D. Analog bar grapH.

Explanation
The analog bar graph on the Fluke 8025A's display section indicates the absolute value of the input.

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50.

(016) Which feature of the Fluke 8025A locks the measurement into the display for viewing and automatically updates the display when you take a new measurement?
- A.
  
  Rotary switch.
- B.
  
  Range push button.
- C.
  
  Power-up self-test.
- D.
  
  Touch-hold push button.
Correct Answer
D. Touch-hold push button.

Explanation
The touch-hold push button feature on the Fluke 8025A locks the measurement into the display for viewing and automatically updates the display when a new measurement is taken. This means that once a measurement is made, it will remain on the screen until a new measurement is taken, ensuring that the user can easily view and compare the results without the need to constantly hold down a button.

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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
Oct 21, 2013

Quiz Created by
Fjeffkirk

3D1X3 Vol 1 CDC Ed 2

(001) What is one reason for modulation that involves modulatiing low frequency signals for transmission over long distances?

(001) What are the three general categories used to produce modulation in radio frequency (RF) transmission today?

(002) When the modulating signal and carrier signal are combined within a modulator, the output signal contains

(002) If a carrier frequency of 1 MHz and a modulating tone of 10 kHz goes to the modulator, the output signal include

(002) The bandwidth of an amplitude modulated signal is

(002) Use the formula on page 1–3. If an oscilloscope displays a modulation envelope having an Emax of 200 volts and an Emin of 20 volts, what is the modulation percentage?

(002) Which statement concerning bandwidth is true?

(003) The output of the oscillator in a frequency modulation (FM) modulator increases in frequency with each

(003) In frequency modulation, a significant sideband contains at least what percentage of the total transmitted power?

(003) What is the formula to find the modulating index?

(003) A 5 kHz modulating signal has enough peak voltage to cause a deviation of 15 kHz. What is the modulation index?

(003) What is it called when a narrow frequency band between adjacent stations prevent frequency modulated sidebands from overlapping?

(004) In phase modulation, what part of the carrier signal is varied?

(004) In phase modulation, the carrier’s

(005) What is the first step in the pulse code modulation process?

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

(006) In asynchronous transmissions, what bit is used by the receiving device to verify that the transmission was received correctly?

(006) If an error should occur, what transmission is lost in an synchronous transmission?

(007) When using vertical redundancy check, what significance does the amount of ones have in a data bit pattern?

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

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

(008) Light sources that are applicable to fiber optic waveguide are light-emitting diodes and

(008) What type of light is emitted from a laser?

(009) What are the two main types of photodetectors?

(009) What photo detector converts one photon to one electron?

(010) Which repeater amplifies optical signal without converting to and from the electrical domain?

(011) A short section of single fiber cable that has a connector at each end is called a

(011) Which fiber-optic connector uses quick-release, keyed bayonet couplings that are preferred in situations where severe vibrations are not expected?

___________ close your mouth.

(012) High-altitude electromagnetic pulse is a wideband phenomenon that involves which frequency range?

(012) A system-generated electromagnetic pulse is a problem for satellites and reentry vehicles that are

(012) High-altitude electromagnetic pulse environment protection is important for critical, time urgent mission systems because it

(012) Which distinct region of the source region electromagnetic pulse is produced by the interactions between the weapon products and the earth’s atmosphere?

(012) Atmospheric disturbances from initial nuclear radiation on higher frequencies affect communications by

(013) Currents and voltages induced on power lines, cable links, and pipelines by electromagnetic pulse are called

(013) Which type of filters are always used in combination with surge arresters?

(014) If the interference can be eliminated by disconnecting the receiving antenna, the source of the disturbance is most likely

(014) Little or no variations in the strength of the interfering signal when moving the receiving antenna for short distance normally indicates

(014) What type of electromagnetic interference occurs when a receiver responds to off-frequency signals?

(014) Which type of intermodulation interference varies significantly with temperature and weather conditions?

(014) How can you normally eliminate electromagnetic interference noise bursts caused by sodium and mercury vapor lights that have stopped working while the power is still applied?

What man-made noise results from voltage surges, arcing, or corona discharges?

(015) What Air Force program is used to resolve an electromagnetic interference incident?

(015) At what level does the Air Force want electromagnetic interference problems resolved?

(015) What do you do when you are reasonably sure electromagnetic interference exists?

(015) Who is initially responsible for reporting an electromagnetic interference?

(015) Who is tasked to provide interference resolution support to the unified commanders?

(016) Which feature of the Fluke 8025A multimeter do you use to select various measurement functions?

(016) Which part of the Fluke 8025A’s display section indicates the absolute value of the input?

(016) Which feature of the Fluke 8025A locks the measurement into the display for viewing and automatically updates the display when you take a new measurement?