Rf 3D1X3 CDC Vol 1 Unit 1-4

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  • 1/64 Questions

    (002) The bandwidth of an amplitude modulated signal is

    • Two times the modulating signal
    • The same as the modulating signal
    • Determined by the modulation index
    • Defined in terms of maximum amount of modulation
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About This Quiz

This RF 3d1x3 CDC Vol 1 Unit 1-4 quiz assesses knowledge on modulation techniques and RF transmission, focusing on the reasons for modulation, categories of modulation, and calculating signal bandwidth. It is essential for learners in military communications roles, enhancing their understanding of RF signal processing.

Rf 3D1X3 CDC Vol 1 Unit 1-4 - Quiz

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  • 2. 

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

    • Binary amplitude shift keying, frequency shift keying, and phase shift keying

    • Pulse amplitude, frequency, and phase

    • Amplitude, frequency, and phase

    • Analog, digital and shift keying

    Correct Answer
    A. 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 amplitude of the carrier signal to transmit information. Frequency modulation (FM) involves varying the frequency of the carrier signal. Phase modulation (PM) involves varying the phase of the carrier signal. These modulation techniques are widely used in radio frequency transmission to encode and transmit information efficiently and reliably.

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  • 3. 

    (001) What reason for modulation involves modulating low frequency signals for transmission over long distances?

    • Spectrum conservation

    • Channel allocation

    • Ease of radiation

    • Companding

    Correct Answer
    A. 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 efficiently transmitted and radiated without significant loss or distortion. By modulating the low frequency signals, the signal can be effectively transmitted over long distances without experiencing significant degradation or interference. This is important for ensuring clear and reliable communication over long distances.

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  • 4. 

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

    • Modulating signal, upper sideband, lower sideband

    • Carrier, upper sideband, and lower sideband

    • Upper sideband and modulating signal

    • Carrier and modulating signal

    Correct Answer
    A. Carrier, upper sideband, and lower sideband
    Explanation
    When the modulating signal and carrier signal are combined within a modulator, the output signals contain a carrier signal, an upper sideband, and a lower sideband. This is because the modulating signal is used to modulate the carrier signal, resulting in the creation of sidebands above and below the carrier frequency. These sidebands carry the information from the modulating signal. Therefore, the output signals consist of the original carrier signal along with the upper and lower sidebands.

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  • 5. 

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

    • Light emitting diode (LED)

    • Avalanche photodiode

    • Positive intrinsic negative (PIN) diode

    • Integrated photodiode/preamplifier (IDP)

    Correct Answer
    A. Positive intrinsic negative (PIN) diode
    Explanation
    The correct answer is positive intrinsic negative (PIN) diode. A PIN diode is a type of photo detector that converts one photon to one electron. It is designed with an intrinsic layer between the p-type and n-type layers, which allows for efficient photon absorption and electron-hole pair generation. This makes it suitable for applications that require high sensitivity and low noise, such as optical communication systems and photovoltaic devices.

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  • 6. 

    (010) What is used to extend the distance of a fiber optic communication systems link?

    • Receiver

    • Transmitter

    • Repeater

    • Patch cords

    Correct Answer
    A. Repeater
    Explanation
    A repeater is used to extend the distance of a fiber optic communication system's link. A repeater receives the optical signal, converts it to an electrical signal, amplifies it, and retransmits it as an optical signal. This process allows the signal to travel over longer distances without losing its strength or quality. By placing repeaters at intervals along the fiber optic link, the signal can be effectively transmitted over long distances, making it an essential component for extending the reach of fiber optic communication systems.

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  • 7. 

    (015) Who is initially responsible for reporting an EMI?

    • The operator

    • MAJCOM

    • Frequency manager (FM)

    • FCC

    Correct Answer
    A. The operator
    Explanation
    The operator is initially responsible for reporting an EMI. This means that it is the operator's duty to report any instances of electromagnetic interference that they encounter. They are the first line of defense in identifying and addressing EMI issues, and it is their responsibility to bring it to the attention of the appropriate authorities for further investigation and resolution.

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  • 8. 

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

    • Photo transistors

    • Hybrid photodiodes

    • Semiconductor laser diodes

    • Integrated photodiode/preamplifiers

    Correct Answer
    A. Semiconductor laser diodes
    Explanation
    Semiconductor laser diodes are applicable to fiber optic waveguides because they provide a concentrated and coherent beam of light that can efficiently transmit through the fiber optic cable. LED light sources are also applicable, but they have a wider beam and are less efficient for long-distance transmission. Photo transistors and hybrid photodiodes are not used as light sources, but rather as detectors to receive the light signal at the end of the fiber optic cable. Integrated photodiode/preamplifiers are also used as detectors, but not as light sources.

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  • 9. 

    (013) Which one of the following statements are true concerning shielding?

    • Cables should be of unshielded construction

    • Only ventilation ports are shielded along the walls

    • Sensitive equipment will be located within the shielded barrier

    • All power lines supplying shielded areas does not require filters

    Correct Answer
    A. Sensitive equipment will be located within the shielded barrier
    Explanation
    Sensitive equipment needs to be located within a shielded barrier to protect it from electromagnetic interference. Shielding helps to block or reduce the electromagnetic radiation that can interfere with the proper functioning of sensitive equipment. By placing the equipment within a shielded barrier, it is protected from external electromagnetic interference, ensuring its performance and reliability.

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  • 10. 

    (014) What is an example of intentionally induced electromagnetic interference (EMI)?

    • Jamming

    • Spurious responses

    • Intermodulation

    • Power line noise

    Correct Answer
    A. Jamming
    Explanation
    An example of intentionally induced electromagnetic interference (EMI) is jamming. Jamming refers to the deliberate disruption or interference of electronic communications, such as radio signals or wireless networks, by transmitting a strong interfering signal. This interference can disrupt or block the intended communication, causing interference and rendering the system ineffective.

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  • 11. 

    (015) At what level does the AF want EMI interference problems resolved?

    • Affected unit

    • Affected major command

    • Electromagnetic environmental effects office

    • Spectrum interference resolution office

    Correct Answer
    A. Affected unit
    Explanation
    The AF wants EMI interference problems resolved at the affected unit level. This means that the responsibility for resolving these issues lies with the specific unit or organization that is experiencing the interference problem. They are expected to take appropriate measures to mitigate and resolve the interference to ensure smooth operations.

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  • 12. 

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

    • Deviation divided by frequency of modulation

    • Deviation times frequency of modulation

    • Sideband divide by carrier frequency

    • Sideband times carrier frequency

    Correct Answer
    A. Deviation divided by frequency of modulation
    Explanation
    The formula to find the modulating index is the deviation divided by the frequency of modulation. The modulating index represents the ratio of the maximum deviation of the carrier frequency to the frequency of the modulating signal. By dividing the deviation by the frequency of modulation, we can calculate the modulating index, which is a crucial parameter in frequency modulation (FM) systems.

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  • 13. 

    (015) What is the first step in the AF spectrum interference resolution (SIR) program?

    • Identify the source

    • Verifying the source

    • Resolving the interference

    • Reporting the interference

    Correct Answer
    A. Identify the source
    Explanation
    The first step in the AF spectrum interference resolution (SIR) program is to identify the source of the interference. This involves determining the specific device or system that is causing the interference in order to effectively address and resolve the issue. Once the source is identified, further steps can be taken to verify, resolve, and report the interference.

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  • 14. 

    (017) When testing a diode with the 8025A, the leads across a "good" diode produces an "OL" (open) on the display in one direction while reversing the leads produces

    • A continuous audible tone

    • "SL" (short) on he display

    • A wavering audible tone

    • Three short beeps

    Correct Answer
    A. A continuous audible tone
    Explanation
    When testing a diode with the 8025A, a "good" diode will produce an "OL" (open) on the display in one direction, indicating that there is no current flow. However, when the leads are reversed, a continuous audible tone is produced. This indicates that the diode is functioning properly and allowing current to flow in the reverse direction.

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  • 15. 

    (002) The amount of effect or change that intelligence has on the carrier in an amplitude modulated signal is expressed as the

    • Percent of modulation

    • Modulation index

    • Bandwidth

    • Deviation

    Correct Answer
    A. Percent of modulation
    Explanation
    The correct answer is percent of modulation. In amplitude modulation, the amount of effect or change that intelligence has on the carrier signal is expressed as the percent of modulation. This refers to the percentage of change in the amplitude of the carrier signal caused by the modulation process. The percent of modulation is a measure of the strength or intensity of the modulating signal in relation to the carrier signal. It determines the depth of modulation and affects the overall quality and fidelity of the modulated signal.

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  • 16. 

    (011) Short sections of signle fiber cables that has a connector at each end is called a

    • Pigtail

    • Patch cord

    • Jumper

    • Breakout cables

    Correct Answer
    A. Patch cord
    Explanation
    A short section of single fiber cables that has a connector at each end is called a patch cord. It is used to connect devices or components in a network or communication system. Patch cords are typically used for temporary or semi-permanent connections and are often color-coded for easy identification. They are commonly used in data centers, telecommunications, and computer networking environments.

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  • 17. 

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

    • Susceptible to the wideband frequency phenomenon

    • Directly exposed to nuclear radiations from a high-altitude burst

    • Affected by the azimuthal magnetic fields and time-varying air conductivity

    • Influenced by the signal fading or waveform distortion caused by the structured plasma field

    Correct Answer
    A. Directly exposed to nuclear radiations from a high-altitude burst
    Explanation
    Satellites and reentry vehicles that are directly exposed to nuclear radiations from a high-altitude burst are susceptible to a system-generated electromagnetic pulse. This is because the nuclear radiation from the burst can generate an electromagnetic pulse that can disrupt or damage the electronic components of the satellites and reentry vehicles.

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  • 18. 

    (013) What is the purpose of bonding?

    • To isolate facility from any external electrical electromagnetic propagation

    • To reduce interference coupling around circuits and around interconnecting lines

    • To ensure a mechanically strong, low impedance interconnection between metal objects

    • To eliminate harmful differences of potential between the various telephone cables entering facility

    Correct Answer
    A. To ensure a mechanically strong, low impedance interconnection between metal objects
    Explanation
    The purpose of bonding is to ensure a mechanically strong, low impedance interconnection between metal objects. This helps to create a reliable and efficient electrical pathway, reducing resistance and preventing the buildup of harmful differences in potential. By establishing a solid bond between metal objects, interference coupling is also minimized, leading to better overall performance and reduced electromagnetic propagation.

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  • 19. 

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

    • Request engineering assistance

    • Contact the base frequency manager

    • Systematically gather data for analysis

    • Contact the spectrum interference resolution (SIR) office

    Correct Answer
    A. Systematically gather data for analysis
    Explanation
    When you are reasonably sure electromagnetic interference (EMI) exists, the best course of action is to systematically gather data for analysis. This means collecting relevant information and evidence related to the interference, such as the timing, location, and nature of the interference. By gathering this data, you can analyze and identify the source of the EMI, which will help in finding a solution to mitigate or eliminate the interference. Requesting engineering assistance, contacting the base frequency manager, or reaching out to the spectrum interference resolution (SIR) office may be necessary steps in the process, but the initial step should be to systematically gather data for analysis.

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  • 20. 

    (003) In frequency modulation (FM), what is considered a significant sideband?

    • Sidebands containing at least 1 percent of the total transmitted power

    • Sidebands containing at least 3 percent of the total transmitted power

    • Sidebands containing at least 10 percent of the total transmitted power

    • Sidebands containing at least 0.1 percent of the total transmitted power

    Correct Answer
    A. Sidebands containing at least 1 percent of the total transmitted power
    Explanation
    In frequency modulation (FM), a significant sideband is considered to be one that contains at least 1 percent of the total transmitted power. This means that the sideband carries a substantial amount of the signal information and contributes significantly to the overall transmission. Sidebands containing less than 1 percent of the total transmitted power may not be strong enough to effectively convey the desired information.

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  • 21. 

    (005) A type of pulse modulation (PM) that changes the amplitude of the pulse train to vary according to the amplitude of the input signal is called

    • Pulse width modulation (PWM)

    • Pulse position modulation

    • Pulse duration modulation

    • Pulse amplitude modulation

    Correct Answer
    A. Pulse amplitude modulation
    Explanation
    Pulse Amplitude Modulation (PAM) is a type of pulse modulation where the amplitude of the pulse train is varied according to the amplitude of the input signal. In PAM, the amplitude of the pulses represents the information being transmitted. By varying the amplitude of the pulses, the signal can be modulated to carry different levels of information. Hence, pulse amplitude modulation is the correct answer in this case.

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  • 22. 

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

    • Receiving end

    • In the oscillator

    • Transmitting end

    • 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.

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  • 23. 

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

    • Repeaters

    • Regenerators

    • Optical amplifiers

    • Receiver

    Correct Answer
    A. Optical amplifiers
    Explanation
    Optical amplifiers are devices that amplify optical signals without converting them to and from the electrical domain. Unlike repeaters and regenerators, which regenerate and amplify electrical signals, optical amplifiers directly amplify the optical signal itself. Receivers, on the other hand, are used to detect and convert optical signals back into electrical signals. Therefore, optical amplifiers are the correct answer as they specifically amplify optical signals without any electrical conversion.

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  • 24. 

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

    • Relays

    • Lighting

    • Power line

    • Switching equipment

    Correct Answer
    A. Power line
    Explanation
    Power line noise is the correct answer because voltage surges, arcing, and corona discharges can cause disruptions in the flow of electricity through power lines, resulting in noise. This noise can interfere with the transmission and reception of signals in electronic devices, causing disturbances or poor quality in audio and visual equipment.

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  • 25. 

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

    • Change the bulb

    • Ground out the light fixture

    • Install a noise reject filter on the light

    • Install a noise reject filter on the receiver

    Correct Answer
    A. Change the bulb
    Explanation
    Sodium and mercury vapor lights can produce electromagnetic interference (EMI) noise bursts when they are not functioning properly. This interference can be eliminated by simply changing the bulb. By replacing the faulty bulb, the EMI noise bursts caused by the malfunctioning light will no longer occur, thus resolving the issue. Grounding out the light fixture or installing a noise reject filter may not be effective in this scenario, as the problem lies with the bulb itself. Similarly, installing a noise reject filter on the receiver may not address the issue directly, as the source of the interference is the malfunctioning light.

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  • 26. 

    (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 measurment?

    • Rotary switch

    • Range push button

    • Power-up self-test

    • Touch-hold push button

    Correct Answer
    A. Touch-hold push button
    Explanation
    The touch-hold push button feature of 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 the user decides to take a new measurement or clear the display. This feature allows for easy viewing and recording of measurements without the need to constantly hold down a button or switch.

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  • 27. 

    (017) Which current range on the Fluke 8025A do you select to measure 250 milliamps alternating current (AC)?

    • Microamps DC

    • Microamps AC

    • Milliamps/amp DC

    • Milliamps/amp AC

    Correct Answer
    A. Milliamps/amp AC
    Explanation
    To measure 250 milliamps alternating current (AC) on the Fluke 8025A, you would select the "milliamps/amp AC" current range. This range allows for measuring current in milliamps and is specifically designed for alternating current.

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  • 28. 

    (002) If the modulating audio signal is 10 kHz wide, what is the bandwidth of the transmitted amplitude modulated signal?

    • 5 kHz

    • 10 kHz

    • 15 kHz

    • 20 kHz

    Correct Answer
    A. 20 kHz
    Explanation
    The bandwidth of an amplitude modulated signal is determined by the sum of the highest frequency component of the modulating signal and the carrier frequency. In this case, the modulating audio signal is 10 kHz wide, so the highest frequency component is 10 kHz. If we assume a carrier frequency of 10 kHz, the bandwidth would be the sum of the highest frequency component and the carrier frequency, which is 20 kHz. Therefore, the correct answer is 20 kHz.

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  • 29. 

    (002) Which statement concerning bandwidth is true?

    • Overmodulating increases bandwidth due to the production of harmonics

    • Undermodulating increases bandwidth due to the production of harmonics

    • Overmodulating increases bandwidth due to the output's increased amplitude

    • Undermodulating increases bandwidth due to the output's decreased amplitude

    Correct Answer
    A. Overmodulating increases bandwidth due to the production of harmonics
    Explanation
    Overmodulating increases bandwidth due to the production of harmonics. When a signal is overmodulated, it means that the amplitude of the signal is exceeding the maximum limit. This causes distortion in the signal, resulting in the production of harmonics. These harmonics contain additional frequency components that increase the overall bandwidth of the signal. Therefore, overmodulation leads to an increase in bandwidth due to the presence of harmonics.

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  • 30. 

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

    • Determines parity

    • Determines transmission rate

    • Determines whether transmission is in American Standard code for information Interchange (ASCII) format

    • Determines whether transmission is synchronous or asynchronous

    Correct Answer
    A. Determines parity
    Explanation
    The amount of ones in a data bit pattern determines parity. Parity is a form of error checking where an extra bit, either 0 or 1, is added to a group of bits to make the total number of ones even or odd. This allows the receiver to detect if any errors occurred during transmission. By counting the number of ones in the data bit pattern, the receiver can determine whether the transmission is error-free or if there was a bit error.

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  • 31. 

    (008) What does an optical source do?

    • Terminates fiber optics cable

    • Converts electrical energy into optical energy

    • Extends the distance and to preserve integrity

    • Accepts optical signals and converts them into electrical signals

    Correct Answer
    A. Converts electrical energy into optical energy
    Explanation
    An optical source is a device that converts electrical energy into optical energy. This means that it takes electrical signals and converts them into light signals, which can then be transmitted through fiber optic cables. This conversion is necessary for the transmission of data over long distances and helps to preserve the integrity of the signal.

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  • 32. 

    (008) Laser diode power coupling is measured in which range

    • Megawatt

    • Mircowatt

    • Milliwatt

    • Kilowatt

    Correct Answer
    A. Milliwatt
    Explanation
    Laser diode power coupling is measured in milliwatts. Milliwatt is the unit of power that is equal to one thousandth of a watt. Laser diodes are typically low-power devices, and their power output is usually in the milliwatt range. This measurement is important in determining the efficiency and performance of laser diodes in various applications such as telecommunications, laser pointers, and optical data storage.

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  • 33. 

    (012) What initial nuclear radiation elements generate electromagnetic pulses?

    • Gamma rays and neutrons

    • Thermally generated x-rays

    • Transient radiation effects on electronics

    • Neutrons and thermally generated x-rays

    Correct Answer
    A. Gamma rays and neutrons
    Explanation
    Gamma rays and neutrons are capable of generating electromagnetic pulses. Gamma rays are high-energy photons that can cause ionization and excitation of atoms, leading to the production of electromagnetic pulses. Neutrons, on the other hand, can induce electromagnetic pulses through the process of neutron-induced electromagnetic radiation (NIER). When neutrons interact with materials, they can generate secondary radiation, including electromagnetic pulses. Therefore, gamma rays and neutrons are the initial nuclear radiation elements that can generate electromagnetic pulses.

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  • 34. 

    (012) Atmospheric disturbances from initial nuclear radiation on higher frequencies affect communications by which types of effects?

    • Blackout

    • Absorption

    • Scintillation

    • Attenuation

    Correct Answer
    A. Scintillation
    Explanation
    Scintillation refers 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 the radio waves to scatter and change direction, leading to fluctuations in signal strength. This can disrupt communications by causing signal fading and interference, making it difficult for the receiver to accurately decode the transmitted information.

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  • 35. 

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

    • Sampling

    • Rectifying

    • Oscillating

    • Band limiting

    Correct Answer
    A. Sampling
    Explanation
    The part of the pulse code modulation (PCM) process that converts a continuous time signal into a discrete time signal is sampling. Sampling involves taking regular intervals of the continuous signal and converting them into discrete values. This allows the signal to be represented digitally and processed by a computer or other digital devices. Sampling is a fundamental step in PCM and is necessary to accurately capture and reproduce the original analog signal.

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  • 36. 

    (007) What error detection method adds stacked characters, divides it by 255, and disregards the answer except for the remainder?

    • Checksum

    • Block check character

    • Cyclic redundancy check

    • Vertical redundancy check

    Correct Answer
    A. Checksum
    Explanation
    Checksum is an error detection method that involves adding up all the characters in a message, dividing the sum by 255, and considering only the remainder. This remainder is then appended to the message and sent along with it. At the receiving end, the same process is performed, and if the remainder obtained matches the one received, it indicates that no errors were introduced during transmission. The checksum method is simple and efficient for detecting errors in data transmission.

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  • 37. 

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

    • Incoherent

    • Coherent

    • Ordinary

    • Invisible

    Correct Answer
    A. Coherent
    Explanation
    A laser emits coherent light. Coherent light refers to light waves that have a fixed phase relationship with each other, meaning they are in sync and have the same frequency and wavelength. This allows the light to travel in a narrow, focused beam with minimal spreading or divergence. In contrast, incoherent light consists of waves with random phase relationships, which results in light that is not focused and spreads out in various directions. Therefore, the correct answer is coherent.

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  • 38. 

    (009) A device that accepts optical signals from an optical fiber and converts them into electrical signals is called an optical

    • Regenerator

    • Transmitter

    • Amplifier

    • Receiver

    Correct Answer
    A. Receiver
    Explanation
    A device that accepts optical signals from an optical fiber and converts them into electrical signals is called a receiver. Receivers are an essential component in optical communication systems as they are responsible for converting the optical signals back into electrical signals that can be processed and interpreted by electronic devices. This conversion allows for the transmission of data over long distances using optical fibers.

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  • 39. 

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

    • Biconic

    • Field connector (FC)

    • Straight tip (ST)

    • Sub-miniature, type A (SMA)

    Correct Answer
    A. Straight tip (ST)
    Explanation
    The straight tip (ST) fiber-optic connector uses a quick-release, keyed bayonet design that is preferred in situations where severe vibrations are not expected. This type of connector provides a secure and reliable connection, but it is not as resistant to vibrations as other connectors like the biconic or field connector (FC). The ST connector is commonly used in telecommunications and data networks where stability and ease of installation are important factors.

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  • 40. 

    (014) What type of equioment often generates many spurious emissions?

    • Slow tuning receiver

    • Rapid tuning receiver

    • Slow tuning transmitter

    • Rapid tuning transmitter

    Correct Answer
    A. Rapid tuning transmitter
    Explanation
    A rapid tuning transmitter often generates many spurious emissions. Spurious emissions refer to unwanted radio frequency signals that are generated as a byproduct of the main transmission. Rapid tuning transmitters, due to their ability to quickly change frequencies, may produce additional unintended emissions that can interfere with other communication systems or cause interference. These emissions can be disruptive and can potentially violate regulatory requirements for radio frequency interference.

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  • 41. 

    (015) What AF program is used to resolve an EMI incident?

    • Mishap prevention

    • Frequency management (FM)

    • Electrostatic discharge (ESD) control

    • Spectrum interference resolution (SIR)

    Correct Answer
    A. Spectrum interference resolution (SIR)
    Explanation
    The correct answer is spectrum interference resolution (SIR). SIR is the AF program that is used to resolve an EMI (Electromagnetic Interference) incident. EMI incidents can occur when electromagnetic radiation from one electronic device interferes with the operation of another device. The SIR program is responsible for identifying and resolving these interference issues, ensuring that all electronic systems and equipment in the Air Force operate effectively and without disruption.

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  • 42. 

    (015) What program addresses persistent and recurring interferences problem in joint operations?

    • The reliability and maintainability

    • Joint spectrum interference resolution (SIR)

    • AF spectrum interference resolution (AFSIR)

    • Quick fix interference reduction capability (QFIRC)

    Correct Answer
    A. Joint spectrum interference resolution (SIR)
    Explanation
    Joint spectrum interference resolution (SIR) is the program that addresses persistent and recurring interferences problem in joint operations. This program focuses on resolving interferences in the joint spectrum, which is crucial for effective communication and coordination among different military forces. By identifying and mitigating interferences, SIR helps to improve the reliability and maintainability of communication systems, ensuring smooth joint operations. The other options mentioned, such as reliability and maintainability, AF spectrum interference resolution (AFSIR), and quick fix interference reduction capability (QFIRC), do not specifically address the persistent and recurring interferences problem in joint operations.

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  • 43. 

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

    • Operator

    • Joint spectrum center (JSC)

    • Installation manager (ISM)

    • Federal communications commission (FCC)

    Correct Answer
    A. Joint spectrum center (JSC)
    Explanation
    The joint spectrum center (JSC) is tasked with providing interference resolution support to the unified commanders. This means that they are responsible for helping the commanders address any issues related to interference in the use of the electromagnetic spectrum. The JSC works to ensure that the spectrum is effectively managed and that there is no interference that could disrupt military operations. They provide technical expertise and assistance to help identify and resolve any interference problems that may arise.

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  • 44. 

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

    • 1.01 MHz, 1 MHz, and 0.99 MHz

    • 1.1 MHz, 1 MHz, and 0.9 MHz

    • 1.11 MHz, 1 MHz, 0.99 MHz

    • 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 fed into the modulator, the output signal will include frequencies that are the sum and difference of the carrier frequency and the modulating tone. In this case, the output signal will consist of 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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  • 45. 

    (002) Reducing modulation to less than 100 percent gives

    • More total power

    • A reduction in carrier power

    • No reduction in carrier power

    • A reduction in carrier and sideband power

    Correct Answer
    A. No reduction in carrier power
    Explanation
    Reducing modulation to less than 100 percent means that the amplitude of the modulating signal is reduced, resulting in a decrease in the depth of modulation. This reduction in modulation does not affect the carrier power, as the carrier signal remains unchanged in amplitude. Therefore, there is no reduction in carrier power when modulation is reduced to less than 100 percent.

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  • 46. 

    (009) Small current that flows from a photodiode even with no light is called

    • Dark current

    • Dispersion

    • Distortion

    • Ionization

    Correct Answer
    A. Dark current
    Explanation
    Dark current refers to the small current that flows through a photodiode even in the absence of light. This current is caused by the thermal generation of electron-hole pairs within the photodiode's semiconductor material. As temperature increases, more electron-hole pairs are generated, leading to an increase in dark current. Dark current can affect the accuracy and sensitivity of photodiodes, especially in low-light conditions, and measures are taken to minimize its impact in various applications.

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  • 47. 

    (009) The responsivity of a photo detector is dependent on the

    • Emitter rise time

    • Wavelength of light

    • Signal-to-noise ratio (SNR)

    • Emitter modulation speed

    Correct Answer
    A. Wavelength of light
    Explanation
    The responsivity of a photo detector is dependent on the wavelength of light. Responsivity refers to the ability of a device to convert incident light into an electrical signal. Different photo detectors are designed to be sensitive to specific wavelengths of light. The responsivity is highest at the wavelength that the detector is designed for, and decreases as the wavelength deviates from this value. Therefore, the wavelength of light plays a crucial role in determining the responsivity of a photo detector.

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  • 48. 

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

    • Rusty bolt

    • Co-channel

    • Brute force

    • Spurious responses

    Correct Answer
    A. Spurious responses
    Explanation
    Spurious responses refer to a type of electromagnetic interference (EMI) that occurs when a receiver responds to off-frequency signals. This means that the receiver picks up and responds to signals that are not within its intended frequency range. These off-frequency signals can cause disruptions or distortions in the receiver's performance, leading to interference with the desired signals. Therefore, spurious responses can negatively impact the overall functionality and reliability of the receiver.

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  • 49. 

    (003) In frequency modulation (FM), the amount of oscillator frequency change is

    • Inversely proportional to the amplitude of the modulating signal

    • Directly proportional to the amplitude of the modulating signal

    • Inversely proportional to the phase of the modulating signal

    • Directly proportional to the phase of the modulating signal

    Correct Answer
    A. Directly proportional to the amplitude of the modulating signal
    Explanation
    In frequency modulation (FM), 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 of the oscillator also increases, and vice versa. This relationship allows for the encoding of information in the frequency variations of the FM signal.

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Quiz Review Timeline (Updated): Oct 18, 2023 +

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

  • Current Version
  • Oct 18, 2023
    Quiz Edited by
    ProProfs Editorial Team
  • Nov 23, 2011
    Quiz Created by
    Brocj357
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