3D152 Vol. 1 Unit Review Exercises

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  • 1/69 Questions

    Three categories of synchronization used in digital data circuits are

    • Synchronous, asynchronous, and isochronous
    • Isochronous, asynchronous, and bisynchronous
    • Nonsynchronous, bisynchronous, and synchronous
    • Asynchronous, bisynchronous, and nonsynchronous
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3D152 Quizzes & Trivia
About This Quiz

The 3D152 Vol. 1 Unit Review Exercises quiz assesses knowledge in analog and digital modulation techniques, including PCM, CVSD, and SSBSC. It covers essential concepts like sidebands and bandwidth requirements, crucial for professionals in telecommunications and signal processing.

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  • 2. 

    What converts analog signal information into an analog carrier signal?

    • Delta modulation (DM)

    • Digital modulation

    • Analog modulation

    • Adaptive modulation

    Correct Answer
    A. Analog modulation
    Explanation
    Analog modulation is the process of converting analog signal information into an analog carrier signal. This is achieved by varying one or more of the characteristics of the carrier signal, such as amplitude, frequency, or phase, in accordance with the input analog signal. By doing so, the analog signal is superimposed onto the carrier signal, allowing for the transmission of the original analog information over a communication channel.

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  • 3. 

    The information-carrying components that occur on either side of a cerrier are called

    • Sidebands

    • Sine waves

    • Frequency translators

    • Modulating frequencies

    Correct Answer
    A. Sidebands
    Explanation
    Sidebands are the information-carrying components that occur on either side of a carrier. In a modulated signal, the carrier wave is modified by adding or subtracting frequencies, resulting in the creation of sidebands. These sidebands contain the actual information being transmitted, while the carrier wave simply serves as a reference for the transmission. Therefore, sidebands accurately describe the components that occur on either side of a carrier.

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  • 4. 

    The only basic waveform in nature is a

    • Carrier wave.

    • Pure sine wave.

    • Resultant wave.

    • Composite wave.

    Correct Answer
    A. Pure sine wave.
    Explanation
    A pure sine wave is the only basic waveform in nature because it represents a single frequency without any harmonics or distortions. It is a smooth, continuous waveform that is commonly found in natural phenomena such as sound waves, electromagnetic waves, and vibrations. Other waveforms, such as composite waves, are made up of multiple frequencies and can be created by combining different sine waves. Therefore, a pure sine wave is the most fundamental and simplest waveform in nature.

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  • 5. 

    If 100 percen modulation is exceeded and there is distortion in the modulating signal, additional sidebands are generated. We identify these sidebands as what?

    • Transmitted intelligence

    • Intensity of speech

    • Composite waves

    • Splatter

    Correct Answer
    A. Splatter
    Explanation
    When the modulation signal exceeds 100 percent and distortion occurs, additional sidebands are generated. These additional sidebands are identified as "splatter." Splatter refers to unwanted and excessive sidebands that can cause interference and distortion in the transmitted signal.

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  • 6. 

    What is the main advantage of differential phase shift keying (DPSK)?

    • Carrier presence is required to detect changes.

    • It requires a less complex receiver than a basic phase shift keying (PSK) signal.

    • It requires a more complex receiver than a basic PSK signal.

    • The demodulator needs to detect changes in absolute phase values.

    Correct Answer
    A. It requires a less complex receiver than a basic phase shift keying (PSK) signal.
    Explanation
    Differential phase shift keying (DPSK) has the main advantage of requiring a less complex receiver compared to basic phase shift keying (PSK) signals. In DPSK, the receiver only needs to detect changes in the relative phase between consecutive symbols, rather than detecting absolute phase values. This simplifies the receiver design and reduces its complexity.

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  • 7. 

    What converts analog signal information into a digital carrier signal?

    • Delta modulation (DM)

    • Analog modulation

    • Digital modulation

    • Adaptive modulation

    Correct Answer
    A. Digital modulation
    Explanation
    Digital modulation is the process of converting analog signal information into a digital carrier signal. This involves encoding the analog signal into a series of discrete digital symbols, which can then be transmitted over a digital communication system. Digital modulation techniques, such as amplitude shift keying (ASK), frequency shift keying (FSK), and phase shift keying (PSK), are commonly used to achieve this conversion. These techniques allow for efficient and reliable transmission of digital data over long distances, and are widely used in modern communication systems.

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  • 8. 

    In Time Division Multiplexing (TDM), the transmitting multiplexer will put a bit or a byte from each of the incoming lines into a specifically allocated what?

    • Channel

    • Trunk

    • Time slot

    • Port

    Correct Answer
    A. Time slot
    Explanation
    In Time Division Multiplexing (TDM), the transmitting multiplexer will put a bit or a byte from each of the incoming lines into a specifically allocated time slot. This time slot is a designated portion of the overall transmission time that is assigned to each individual line. By allocating a specific time slot for each line, TDM ensures that multiple signals can be transmitted simultaneously over a single communication channel without interference.

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  • 9. 

    Any actions we take to protect our forces, facilities, and equipment for electronic action that can destory or degrade our capabilites is considered

    • Electronic combat

    • Electronic protection

    • Electronic attack

    • Electronic warfare support

    Correct Answer
    A. Electronic protection
    Explanation
    Electronic protection refers to the measures taken to safeguard our forces, facilities, and equipment from electronic actions that can either destroy or weaken our capabilities. This can include various techniques and technologies used to prevent or mitigate the effects of electronic attacks, such as encryption, firewalls, and signal jamming. By implementing electronic protection, we aim to ensure the integrity and effectiveness of our electronic systems and maintain a strong defense against potential threats.

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  • 10. 

    The upper sideband in a single-sideband suppressed carrier (SSBSC) modulation is eliminated by

    • Filtering.

    • Detection.

    • Compression.

    • Companding.

    Correct Answer
    A. Filtering.
    Explanation
    In a single-sideband suppressed carrier (SSBSC) modulation, the upper sideband is eliminated by filtering. Filtering refers to the process of selectively allowing certain frequencies to pass through while blocking or attenuating others. In the case of SSBSC modulation, a filter is used to remove the upper sideband, leaving only the lower sideband and the carrier signal. This filtering process helps in reducing bandwidth requirements and improving the efficiency of transmission.

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  • 11. 

    When using an ohmmeter to take a reisistance reading, what preliminary precaution should you take?

    • Properly seat the test lead into the current input terminal jack

    • Disconnect the power from the circuit being tested

    • Place the meter in the frequency mode

    • Set the range for maximum reading

    Correct Answer
    A. Disconnect the power from the circuit being tested
    Explanation
    Before using an ohmmeter to take a resistance reading, it is important to disconnect the power from the circuit being tested. This precaution is necessary to ensure the safety of the person conducting the measurement and to prevent any potential damage to the ohmmeter or the circuit. By disconnecting the power, the risk of electric shock or short-circuiting the circuit is minimized, allowing for accurate and safe resistance readings to be taken.

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  • 12. 

    Which statement best describes a binary with eight-zero substitution (B8ZS) signal?

    • The information is transmitted in three different voltage levels

    • A logic one is transmitted as positive voltage if the previous logic one was negative

    • The level always returns to zero for 50 percent of the bit cycle after every transition

    • Bipolar violations are intentionally inserted into a data signal to break up long strings of zeros

    Correct Answer
    A. Bipolar violations are intentionally inserted into a data signal to break up long strings of zeros
    Explanation
    B8ZS is a line code used in telecommunications to ensure that long strings of zeros are not transmitted. It intentionally inserts bipolar violations into the data signal, which breaks up the long strings of zeros. This helps in maintaining synchronization and prevents loss of signal.

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  • 13. 

    Which section of a bit error rate test (BERT) set measures the received test pattern?

    • Transmitter

    • Emitter

    • Detector

    • Receiver

    Correct Answer
    A. Receiver
    Explanation
    The receiver section of a bit error rate test (BERT) set measures the received test pattern. This is because the receiver is responsible for receiving the transmitted test pattern and comparing it to the expected pattern to determine the number of errors. The other options (transmitter, emitter, and detector) are not directly involved in measuring the received test pattern in a BERT set.

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  • 14. 

    The form of pulse modulation in which the pulse is varied within a set range of positions is known as

    • Pulse-amplitude modulation (PAM)

    • Pulse-duration modulation (PDM)

    • Pulse-position modulation (PPM)

    • Pulse-code modulation (PCM)

    Correct Answer
    A. Pulse-position modulation (PPM)
    Explanation
    Pulse-position modulation (PPM) is a form of pulse modulation where the position of the pulse within a set range is varied. In PPM, the amplitude and duration of the pulse remain constant, but the position of the pulse within a time slot is changed to represent different information. This allows for efficient use of the available bandwidth and enables the transmission of multiple signals simultaneously. PPM is commonly used in applications where timing accuracy is critical, such as in radar and communication systems.

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  • 15. 

    How many bits per character of a 16-step pulse-code modulation (PCM) system are used to describe the quantized analog sample?

    • 3

    • 4

    • 5

    • 8

    Correct Answer
    A. 4
    Explanation
    In a 16-step PCM system, there are 16 possible quantized analog samples. To describe these samples, each sample needs to be represented using a certain number of bits. Since there are 16 possible samples, the number of bits needed to represent them can be determined by finding the smallest power of 2 that is greater than or equal to 16. In this case, the smallest power of 2 greater than or equal to 16 is 2^4, which is 16. Therefore, 4 bits per character are used to describe the quantized analog sample in a 16-step PCM system.

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  • 16. 

    Wave-division multiplexing (WDM) creates the virtual channels for multiplexing them together for transmission by using different

    • Wavelengths or lambdas

    • Wavelengths or gammas

    • Frequencies or lambdas

    • Frequencies or gammas

    Correct Answer
    A. Wavelengths or lambdas
    Explanation
    Wavelength-division multiplexing (WDM) is a technology that combines multiple optical signals onto a single optical fiber by assigning each signal a different wavelength or lambda. This allows for the transmission of multiple channels of data simultaneously. The correct answer is "wavelengths or lambdas" because WDM uses different wavelengths or lambdas to create virtual channels and multiplex them together for transmission. Frequencies or gammas are not used in WDM.

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  • 17. 

    The most common wave-division multiplexing (WDM) system uses how many wavelengths?

    • One wavelength

    • Two wavelengths

    • Three wavelengths

    • Four wavelengths

    Correct Answer
    A. Two wavelengths
    Explanation
    The most common wave-division multiplexing (WDM) system uses two wavelengths. WDM is a technique that allows multiple optical signals to be transmitted simultaneously over a single fiber optic cable. Each signal is assigned a different wavelength, and these wavelengths are combined and transmitted together. By using two wavelengths, the WDM system can effectively double the capacity of the fiber optic cable, allowing for more data to be transmitted at the same time.

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  • 18. 

    What unit is most commonly used in data systems to express signaling speed?

    • Baud

    • Baudot

    • Sense interface

    • Bits per second

    Correct Answer
    A. Bits per second
    Explanation
    The unit most commonly used in data systems to express signaling speed is "bits per second". Baud is a unit used to measure the number of signal changes per second, but it does not directly correspond to the number of bits transmitted. Baudot is a character encoding scheme used in telegraphy, not a unit of signaling speed. Sense interface is not a commonly used unit in data systems.

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  • 19. 

    In what type of signal does the signal level move to one of the discrete signal levels, but returns to the zero level after a predetermined time?

    • Non-return-to-zero (NRZ) level

    • Non-return-to-zero mark

    • Non-return-to-zero space

    • Return-to-zero

    Correct Answer
    A. Return-to-zero
    Explanation
    Return-to-zero is the type of signal in which the signal level moves to one of the discrete signal levels, but returns to the zero level after a predetermined time. In this type of signal, the absence of a signal is represented by the zero level, and the presence of a signal is represented by a non-zero level. This allows for easier synchronization and clock recovery, as the signal returns to zero at regular intervals.

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  • 20. 

    What communications control signal uses a two-frequency dialing combination?

    • Pulse dialing

    • Tone dialing

    • Digit dialing

    • Address dialing

    Correct Answer
    A. Tone dialing
    Explanation
    Tone dialing is the correct answer because it uses a two-frequency dialing combination to send signals over a telephone line. Unlike pulse dialing, which uses a series of intermittent pulses, tone dialing uses specific tones for each digit on the telephone keypad. These tones are generated by pressing the buttons on the keypad, and they are then transmitted as a two-frequency signal to the telephone exchange, enabling the call to be connected. This method of dialing is more efficient and accurate compared to pulse dialing.

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  • 21. 

    When is the voltage applied in loop-start signaling?

    • When dial tone is present

    • On-hook condition

    • Off-hook condition

    • During the ringback signal

    Correct Answer
    A. Off-hook condition
    Explanation
    In loop-start signaling, the voltage is applied when the telephone receiver is off-hook. When the receiver is lifted off the hook, it indicates that the user wants to make a call, and the voltage is applied to establish the connection. The off-hook condition is necessary for the voltage to be applied in loop-start signaling.

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  • 22. 

    The definition of electronic attack can be found in which publication?

    • Air Force Doctrine Document 2-5.1

    • Air Force Instruction 10-101

    • Air Force Policy Memorandum 2-1

    • Air Force Manual 2-5.1

    Correct Answer
    A. Air Force Doctrine Document 2-5.1
    Explanation
    The correct answer is Air Force Doctrine Document 2-5.1. This publication is likely to contain the definition of electronic attack as it is a doctrine document, which typically provides guidance and information on specific subjects related to the Air Force's operations and procedures. This document is likely to be a comprehensive source of information on electronic attack, making it the most appropriate publication to find the definition.

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  • 23. 

    What form of modulation is insensitive to signal variations?

    • Delta

    • Frequency shift keying (FSK)

    • Pulse-amplitude modulation (PAM)

    • Binary-phase shift keying or bi-phase shift keying (BPSK)

    Correct Answer
    A. Binary-phase shift keying or bi-phase shift keying (BPSK)
    Explanation
    Binary-phase shift keying or bi-phase shift keying (BPSK) is insensitive to signal variations because it uses a single carrier frequency and shifts the phase of the carrier signal to represent the binary data. It does not rely on variations in signal frequency or amplitude to transmit information. Therefore, BPSK is not affected by signal variations such as changes in frequency or amplitude, making it a robust modulation technique.

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  • 24. 

    The method of multiplexing the T1 multiplexer uses is

    • Frequency division

    • Binary division

    • Pulse division

    • Time division

    Correct Answer
    A. Time division
    Explanation
    The method of multiplexing used by the T1 multiplexer is time division. Time division multiplexing involves dividing the available transmission time into multiple time slots and assigning each slot to a different input signal. In the case of T1 multiplexing, the time slots are used to combine multiple voice or data channels into a single high-speed transmission line. This allows for efficient utilization of the available bandwidth and simultaneous transmission of multiple signals over a single line.

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  • 25. 

    Which statement best describes an alternate mark inversion (AMI) signal?

    • The information is transmitted in three different voltage levels

    • A logic one is transmitted as positive voltage if the previous logic one was negative

    • The level always returns to zero for 50 percent of the bit cycle after every transition

    • Bipolar violations are intentionally inserted into a data signal to break up long strings of zeros

    Correct Answer
    A. A logic one is transmitted as positive voltage if the previous logic one was negative
    Explanation
    An alternate mark inversion (AMI) signal is a type of line code used for transmitting digital data. In this type of signal, a logic one is transmitted as a positive voltage if the previous logic one was negative. This helps in maintaining a balance between positive and negative voltage levels, preventing the accumulation of DC bias. By alternating the polarity of consecutive logic ones, it ensures that the level always returns to zero for 50 percent of the bit cycle after every transition. This helps in synchronization and error detection.

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  • 26. 

    In commin associated signaling (CAS), what is the seventh bit in frames 6 and 12 used to convey signaling information know as?

    • Bit robbing

    • Bit stuffing

    • Frame correction

    • Frame enhancement

    Correct Answer
    A. Bit robbing
    Explanation
    The seventh bit in frames 6 and 12 in common associated signaling (CAS) is used to convey signaling information known as "Bit robbing." Bit robbing refers to the practice of stealing one bit from each byte in a frame to be used for signaling purposes. This technique allows for the transmission of additional information without the need for additional bits or frames.

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  • 27. 

    What is an examplel of analog-to-digital and digital-to-analog techniques?

    • Amplitude modulation (AM) and frequency modulation (FM)

    • Pulse code modulation (PCM) and frequency shift keying (FSK)

    • Phase modulation (PM) and quadrature phase shift keying (QPSK)

    • Pulse code modulation (PCM) and continuously variable slope delta (CVSD) modulation

    Correct Answer
    A. Pulse code modulation (PCM) and continuously variable slope delta (CVSD) modulation
    Explanation
    Pulse code modulation (PCM) and continuously variable slope delta (CVSD) modulation are examples of analog-to-digital and digital-to-analog techniques. PCM is a method of converting analog signals into digital signals by sampling the amplitude of the signal at regular intervals. CVSD modulation is a technique that converts analog signals into digital signals by encoding the changes in the slope of the signal. Both techniques involve the conversion of analog signals to digital signals and vice versa, making them examples of analog-to-digital and digital-to-analog techniques.

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  • 28. 

    We can express the 6-to-1 improvement of the single-sideband suppressed carrier (SSBSC) modulation over conventional amplitude modulation (AM) as

    • 2 decibels (dB) of improvement.

    • 4 dB of improvement.

    • 6 dB of improvement.

    • 8 dB of improvement.

    Correct Answer
    A. 8 dB of improvement.
    Explanation
    The improvement of SSBSC modulation over AM can be expressed in terms of decibels (dB). Since the question states that the improvement is 6-to-1, it means that the power ratio of SSBSC to AM is 6:1. To convert this power ratio into decibels, we use the formula: dB = 10 * log10(power ratio). Plugging in the values, we get dB = 10 * log10(6/1) = 10 * log10(6) ≈ 7.78 dB. Since we are looking for the closest option, the correct answer is 8 dB of improvement.

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  • 29. 

    The process of coding pulse code modulation (PCM) quantized pulses to make them a constant duration and amplitude is

    • Encoding

    • Companding

    • Uniform quantizing

    • Nonuniform quantizing

    Correct Answer
    A. Encoding
    Explanation
    The process of coding pulse code modulation (PCM) quantized pulses to make them a constant duration and amplitude is encoding. This involves converting the analog signal into a digital format by assigning specific codes to each sample of the signal. The encoding process ensures that the quantized pulses maintain a consistent duration and amplitude, allowing for accurate transmission and reconstruction of the original signal.

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  • 30. 

    Individual pulses within a digital signal are

    • Bits

    • Bytes

    • Codes

    • Blocks

    Correct Answer
    A. Bits
    Explanation
    Individual pulses within a digital signal are referred to as bits. In digital communication, information is represented using binary digits or bits, which can have a value of either 0 or 1. These bits are used to encode and transmit data in the form of electrical or optical pulses. Each pulse represents a single bit, and the sequence of these bits forms the digital signal. Therefore, the correct answer is bits.

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  • 31. 

    Bit count integrity problems are primarily cause by

    • Impedance mismatch

    • System timing faults

    • Improper equipment settings

    • Changes in atmospheric conditions

    Correct Answer
    A. System timing faults
    Explanation
    Bit count integrity problems refer to issues with the accuracy and reliability of counting bits in a system. System timing faults can cause these problems by disrupting the synchronization and timing of the system, leading to errors in counting the bits accurately. This can result in data corruption, loss of information, or incorrect calculations. Impedance mismatch, improper equipment settings, and changes in atmospheric conditions may cause other types of system errors, but they are not directly related to bit count integrity problems.

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  • 32. 

    In what common channel signaling (CSS) mode are the messages relating to signaling between two points conveyed directly interconnecting these signaling points?

    • Associated mode

    • Nonassociated mode

    • Quasi-associated mode

    • Mulit-associated mode

    Correct Answer
    A. Associated mode
    Explanation
    In the associated mode of common channel signaling (CSS), the messages related to signaling between two points are conveyed directly through an interconnection between these signaling points. This means that the signaling messages are sent directly from one point to another without any intermediate nodes or routing. This mode is commonly used in telecommunication networks where a direct connection is established between the signaling points involved in the communication.

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  • 33. 

    Amplitude modulation (AM) requires a bandwidth that is

    • Twice that of the modulating signal.

    • Half that of the modulating signal.

    • Twice that of the carrier signal.

    • Half that of the carrier signal.

    Correct Answer
    A. Twice that of the modulating signal.
    Explanation
    Amplitude modulation (AM) requires a bandwidth that is twice that of the modulating signal because in AM, the modulating signal is used to vary the amplitude of the carrier signal. The modulating signal contains the information to be transmitted, and its bandwidth determines the range of frequencies needed to accurately represent that information. Since the modulating signal is used to modulate the carrier signal, the bandwidth of the AM signal must be able to accommodate the highest frequency components of the modulating signal, which requires a bandwidth that is twice as wide.

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  • 34. 

    What communications supervisory signal uses a continuous application of direct current voltage for signaling?

    • Record warning

    • Fast busy signal

    • Loop-start

    • E and M

    Correct Answer
    A. Loop-start
    Explanation
    Loop-start is the correct answer because it is a communications supervisory signal that uses a continuous application of direct current voltage for signaling. In loop-start signaling, a continuous current is applied to the signaling loop to indicate that the line is in use or off-hook. This type of signaling is commonly used in analog telephone systems to establish and terminate calls.

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  • 35. 

    Electronic warefare support includes devices such as

    • Anti-radiation missiles and directed energy weapons

    • Intelligence platforms and noise jamming systems

    • Radar warning receivers and intelligence systems

    • Directed energy weapons and radar warning receivers

    Correct Answer
    A. Radar warning receivers and intelligence systems
    Explanation
    Electronic warfare support includes devices such as radar warning receivers and intelligence systems. Radar warning receivers are used to detect and identify radar signals, allowing the operator to take appropriate countermeasures. Intelligence systems, on the other hand, gather and analyze information about enemy electronic systems, helping to identify vulnerabilities and develop effective strategies. Both radar warning receivers and intelligence systems play crucial roles in electronic warfare by providing situational awareness and enabling effective defensive and offensive actions.

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  • 36. 

    Which push-buttons would you select to get 125-ohm impedance on the time domain reflectometer?

    • 50-, 75-, and 125-ohm

    • 75- and 125-ohm

    • 50- and 125-ohm

    • 50- and 75-ohm

    Correct Answer
    A. 50- and 75-ohm
    Explanation
    To get a 125-ohm impedance on the time domain reflectometer, you would need to select the 50-ohm and 75-ohm push-buttons. The total impedance is determined by the sum of the selected push-button values, so by selecting the 50-ohm and 75-ohm push-buttons, you can achieve the desired 125-ohm impedance.

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  • 37. 

    What type of error is the result of two successive logic one pulses of the same polarity in violation of alternate mark inversion coding rules?

    • Cyclic redundancy check

    • Bipolar violation

    • Bit slip

    • Frame

    Correct Answer
    A. Bipolar violation
    Explanation
    A bipolar violation is the result of two successive logic one pulses of the same polarity in violation of alternate mark inversion coding rules. In alternate mark inversion coding, logic one pulses should alternate in polarity. When two consecutive logic one pulses have the same polarity, it is considered a bipolar violation. This violation can cause errors in data transmission and can affect the integrity of the transmitted signal.

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  • 38. 

    The purpose of the miniature ON/OFF switches on a breakout box is to 

    • Measure the individual interface signals

    • Change the voltage of individual interface signals

    • Allow the interruption of the individual interface conductors

    • Allow the cross-patching of the individual interface conductors

    Correct Answer
    A. Allow the interruption of the individual interface conductors
    Explanation
    The purpose of the miniature ON/OFF switches on a breakout box is to allow the interruption of the individual interface conductors. These switches provide a convenient way to open or close the circuit for each interface signal, allowing for easy troubleshooting or testing of individual connections. By interrupting the conductors, the switches can help identify any issues or faults in the interface signals.

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  • 39. 

    A digital signal that contains synchronizing bits within the signal stream describes

    • Synchronous operation

    • Asynchronous operation

    • Synchronous and/or isochronous operation

    • Asynchronous and/or synchronous operation

    Correct Answer
    A. Asynchronous operation
    Explanation
    A digital signal that contains synchronizing bits within the signal stream describes asynchronous operation. This means that the signal is not dependent on a common clock or timing mechanism to synchronize the transmission and reception of data. Instead, the synchronizing bits are used to indicate the start and end of each data packet, allowing the receiver to correctly interpret the information. Asynchronous operation is commonly used in serial communication protocols, such as UART, where data is transmitted bit by bit without a fixed clock signal.

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  • 40. 

    When using a multimeter, which mode should be used if the reading fluctuates and a more accurate reading is desired?

    • Minimum/maximum (MIN/MAX)

    • Display hold

    • Frequency

    • Range

    Correct Answer
    A. Minimum/maximum (MIN/MAX)
    Explanation
    When using a multimeter, the MIN/MAX mode should be used if the reading fluctuates and a more accurate reading is desired. This mode allows the multimeter to continuously measure and display the minimum and maximum values of the reading over a period of time. By doing so, it provides a more accurate representation of the range of values the reading is fluctuating between, allowing for a better understanding of the true measurement.

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  • 41. 

    Which of the following is not considered an analog modulation techniques?

    • Pulse-amplitude modulation (PAM)

    • Pulse-duration modulation (PDM)

    • Pulse-position modulation (PPM)

    • Pulse-code modulation (PCM)

    Correct Answer
    A. Pulse-code modulation (PCM)
    Explanation
    PCM is not considered an analog modulation technique because it is a digital modulation technique. Analog modulation techniques involve encoding analog signals onto a carrier wave, while PCM involves digitizing the analog signal into a series of binary numbers. PCM is commonly used in digital communication systems for transmitting and storing analog signals in a digital format.

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  • 42. 

    The two major types of frame structures are

    • Low speed and high speed

    • High speed and EBCDIC

    • CCITT and low speed

    • EBCDIC and CCITT

    Correct Answer
    A. CCITT and low speed
    Explanation
    The correct answer is CCITT and low speed. CCITT (International Telegraph and Telephone Consultative Committee) is a standard organization that develops recommendations for telecommunication systems. Low speed refers to slower data transmission rates. Therefore, the two major types of frame structures are CCITT, which represents a standard, and low speed, which represents the slower data transmission rate.

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  • 43. 

    Which option is a characteristic of synchronous data operation?

    • Timing pulses are transmitted within the signal stream.

    • Start and stop pulses control data transmission

    • System timing is not of critical importance

    • All data bits are the same length in time

    Correct Answer
    A. All data bits are the same length in time
    Explanation
    In synchronous data operation, all data bits are the same length in time. This means that each bit of data is transmitted for the same duration, ensuring that the receiver can accurately interpret and synchronize with the data stream. This characteristic allows for efficient and reliable data transmission, as it eliminates the need for complex timing mechanisms or adjustments.

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  • 44. 

    When using a multimeter, which mode should be used if the reading is unreadable due to fluctuations?

    • Range

    • Frequency

    • Display hold

    • Minimum/maximum (MIN/MAX)

    Correct Answer
    A. Display hold
    Explanation
    When using a multimeter, the display hold mode should be used if the reading is unreadable due to fluctuations. This mode allows the multimeter to freeze the displayed value, making it easier for the user to read and record the measurement. By holding the reading on the display, it prevents the fluctuations from affecting the accuracy of the measurement.

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  • 45. 

    How many bits are in the extended superframe format (ESF) framing sequence?

    • 8

    • 12

    • 24

    • 48

    Correct Answer
    A. 24
    Explanation
    The extended superframe format (ESF) framing sequence consists of 24 bits. This framing sequence is used in telecommunications to synchronize and frame T1 digital transmission. It helps in the accurate transmission and reception of data by providing a structure for framing and synchronization.

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  • 46. 

    What communications information signal uses a signal cycled on and off for 0.5 second and contains the generation of a 480- and 620-Hz frequency pair?

    • Dial tone

    • Busy signal

    • Off-hook alert

    • Call waiting

    Correct Answer
    A. Busy signal
    Explanation
    A busy signal is a communications information signal that is cycled on and off for 0.5 seconds. It indicates that the line is currently in use or unavailable. The busy signal also generates a frequency pair of 480 and 620 Hz, which is a characteristic feature of this signal.

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  • 47. 

    Jamming a portion of the frequency spectrum is an example of

    • Electronic combat

    • Electronic protection

    • Electronic attack

    • Electronic warfare support

    Correct Answer
    A. Electronic attack
    Explanation
    Jamming a portion of the frequency spectrum is an example of electronic attack. Electronic attack refers to the use of electromagnetic energy to disrupt, deceive, or destroy enemy electronic systems and infrastructure. By jamming a portion of the frequency spectrum, an attacker can interfere with the communication and operation of enemy electronic systems, causing disruption and potentially rendering them ineffective. This can be a critical tactic in modern warfare, as it can disrupt enemy command and control, intelligence gathering, and communication systems.

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  • 48. 

    What are the two major sections of a bit error rate test (BERT) set?

    • Emitter and detector

    • Emitter and receiver

    • Transmitter and detector generator

    • Transmitter and receiver

    Correct Answer
    A. Transmitter and receiver
    Explanation
    A bit error rate test (BERT) set is used to measure the quality of a digital communication system. The two major sections of a BERT set are the transmitter and the receiver. The transmitter is responsible for sending a known pattern of bits, while the receiver receives the transmitted bits and compares them to the original pattern. By analyzing the errors in the received bits, the BERT set can determine the bit error rate of the system. Therefore, the correct answer is "Transmitter and receiver."

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  • 49. 

    While timing makes sure the equipment is sending and receiving bits at the same time intervals, synchronization makes sure that the

    • Receive equipment timing is set properly

    • Transmit equipment timing is set properly

    • Receive equipment can find its place in the bit stream

    • Transmit equipment can find its place in the bit stream

    Correct Answer
    A. Receive equipment can find its place in the bit stream
    Explanation
    Synchronization ensures that the receive equipment can find its place in the bit stream. This means that the timing of the receive equipment is set properly so that it can accurately detect and interpret the incoming bits. Without synchronization, the receive equipment may struggle to identify the correct starting point of the bit stream, leading to errors in data transmission. By synchronizing the receive equipment, it can effectively locate its position in the bit stream and accurately receive the transmitted data.

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Quiz Review Timeline (Updated): Mar 20, 2023 +

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  • Current Version
  • Mar 20, 2023
    Quiz Edited by
    ProProfs Editorial Team
  • Nov 03, 2012
    Quiz Created by
    Konungre

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