3d1x2 Skt Book 1

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  • 1/109 Questions

    The only basic waveform in nature is a pure _____ wave; any other waveform is a "composite" or "resultant" wave.

    • Sine
    • Cosine
    • Tangent
    • Unmodulated
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3d1x2 Skt Book 1 - Quiz
About This Quiz

Explore key modulation techniques in '3D1X2 SKT Book 1'. This quiz assesses understanding of signal modification methods like Modulation, Analog Modulation, and Binary Phase-Shift Keying, vital for professionals in electronics and communication engineering.

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  • 2. 

    _____ is a digital communications link that enables the transmission of voice, data, and video signals at a rate of 1.544 Mbs.

    • OC3

    • T2

    • T1

    • OC12

    Correct Answer
    A. T1
    Explanation
    T1 is a digital communications link that enables the transmission of voice, data, and video signals at a rate of 1.544 Mbs. It is commonly used in North America and Japan for various applications such as telephone networks and internet connections. T1 provides a reliable and efficient means of transmitting data, making it suitable for both residential and business use.

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  • 3. 

    How many code bits are required to provide 16 quantized steps?

    • 3

    • 4

    • 5

    • 6

    Correct Answer
    A. 4
    Explanation
    To provide 16 quantized steps, we need to have enough code bits to represent each step. Since 2^4 equals 16, we need 4 code bits to represent 16 quantized steps. Each additional code bit would double the number of quantized steps, so 4 code bits is the correct answer.

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  • 4. 

    The information-carrying components that occur on either side of a carrier are called _______.

    • Sidebands

    • Sine Waves

    • Frequency Translators

    • Modulating Frequencies

    Correct Answer
    A. Sidebands
    Explanation
    The correct answer is "Sidebands". In a communication system, sidebands refer to the additional frequency components that are produced when a carrier signal is modulated with information. These sidebands carry the encoded information and occur on either side of the carrier frequency. They are essential for transmitting and receiving signals accurately. Sine waves are basic periodic waveforms and not specifically related to information-carrying components. Frequency translators are devices used for frequency conversion, and modulating frequencies are the frequencies used to modulate a carrier signal, but they do not specifically refer to the components occurring on either side of the carrier.

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  • 5. 

    What is the conversion of an analog signal into another analog signal?

    • Analog Modulation

    • Pulse Duration Modulation

    • Digital Modulation

    • Pulse Code Modulation

    Correct Answer
    A. Analog Modulation
    Explanation
    Analog modulation is the process of converting an analog signal into another analog signal. This is achieved by varying one or more properties of the carrier signal in accordance with the input signal. This modulation technique is commonly used in communication systems to transmit analog signals over long distances without significant loss or distortion.

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  • 6. 

    In FM, the modulating signal causes the oscillator to change frequency. How much the oscillator changes frequency is directly proportional to the amplitude of the modulating signal. The larger the modulating signal voltage, the greater is the deviation. The common term for this is __________. __________ is proportional to the amount (amplitude) of the modulating signal.

    • Amount of Deviation

    • Amount of Change

    • Amount of Difference

    • Amount of Signal

    Correct Answer
    A. Amount of Deviation
    Explanation
    The correct answer is "Amount of Deviation". In FM, the modulating signal causes the oscillator to change frequency, and the amount of frequency change is directly proportional to the amplitude of the modulating signal. This is commonly referred to as the "Amount of Deviation".

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  • 7. 

    The big advantage of PM over FM is that this circuit uses a _______-controlled oscillator to maintain a stable carrier frequency.

    • Crystal

    • User

    • CPU

    • Uranium

    Correct Answer
    A. Crystal
    Explanation
    The correct answer is Crystal. In frequency modulation (FM), the carrier frequency is generated by a voltage-controlled oscillator (VCO), which can be less stable compared to a crystal-controlled oscillator. On the other hand, phase modulation (PM) uses a crystal-controlled oscillator to maintain a stable carrier frequency. Crystals are known for their high stability and accuracy in generating frequencies, making them a preferred choice in applications where precise frequency control is required.

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  • 8. 

    In ______, a digital device that can select incoming bits digitally and apportion them over a particular higher-speed bit stream in the same time interval. The transmitting multiplexer will put a bit or a byte from each of the incoming lines into a specifically allocated time slot, and the demultipluxer at the other end of the system, outputs the bits or bytes to their appropriate lines (timeslots) at their operating speeds.

    • Time Divison Multiplexing

    • Frequency Division Multiplexing

    • Wave Division Multiplexing

    • Amplitude Division Multiplexing

    Correct Answer
    A. Time Divison Multiplexing
    Explanation
    Time Division Multiplexing is a technique used in telecommunications to transmit multiple signals over a single channel. In this technique, a digital device selects incoming bits and allocates them to specific time slots in a higher-speed bit stream. The transmitting multiplexer puts a bit or byte from each incoming line into its allocated time slot, and the demultiplexer at the receiving end separates the bits or bytes and outputs them to their appropriate lines. Time Division Multiplexing allows multiple signals to be transmitted simultaneously, increasing the efficiency and capacity of the communication channel.

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  • 9. 

    Amplitude Shift Keying(ASK) is also know as ______ because the amplitude of the carrier was either on or off depending on the state of the digital input.

    • On-Off Keying(OOK)

    • On Keying(OK)

    • Off Keying(OK)

    • Duplex Keying(DK)

    Correct Answer
    A. On-Off Keying(OOK)
    Explanation
    Amplitude Shift Keying (ASK) is a digital modulation technique where the amplitude of the carrier signal is varied to represent digital data. In ASK, the carrier amplitude is either on or off depending on the state of the digital input. This modulation scheme is also known as On-Off Keying (OOK) because the carrier amplitude is switched on and off to represent the digital information.

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  • 10. 

    When we express the term "bit" with regard to time, we have __________. This simply means that we can move a certain number of symbols, states, or conditions in 1 second.

    • Bytes per Second

    • Beats per second

    • Bits per Second

    • Baud per Second

    Correct Answer
    A. Bits per Second
    Explanation
    When we express the term "bit" with regard to time, it means that we can move a certain number of symbols, states, or conditions in 1 second. This is measured in bits per second, which indicates the rate at which data is transmitted or processed. The term "bits per second" is commonly used in telecommunications and computer science to quantify the speed of data transfer or processing.

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  • 11. 

    ______ applied to a digital signal means that when a signal is keyed to one level, it stays at that level until it's keyed to another level; that is, it doesn't return to the zero level during the bit time.

    • Non-Return to Zero

    • Return to Zero

    • Alternate Mark Inversion

    • Binary 8 Zero Substitution

    Correct Answer
    A. Non-Return to Zero
    Explanation
    Non-Return to Zero applied to a digital signal means that when a signal is keyed to one level, it stays at that level until it's keyed to another level. In other words, it doesn't return to the zero level during the bit time. This type of encoding is commonly used in digital communication systems to represent binary data. In Non-Return to Zero, the presence of a signal represents a binary 1, while the absence of a signal represents a binary 0. This encoding method allows for simple detection of the signal transitions and is relatively easy to implement.

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  • 12. 

    ______ allows for the multiple independent transmission of digital information to be sent over a single fiber. This is done through channel separation and the equipments ability to distinguish the separate wavelengths.

    • Wavelength Division Multiplexing

    • Frequency Division Multiplexing

    • Time Division Multiplexing

    • Amplitude Division Multiplexing

    Correct Answer
    A. Wavelength Division Multiplexing
    Explanation
    Wavelength Division Multiplexing allows for the multiple independent transmission of digital information to be sent over a single fiber. This is achieved by separating the channels and using equipment that can distinguish the separate wavelengths.

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  • 13. 

    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
    Wave-division multiplexing (WDM) is a technique used to combine multiple optical signals onto a single optical fiber by assigning each signal a different wavelength or lambda. This allows for the transmission of multiple signals simultaneously without interference. Therefore, the correct answer is wavelengths or lambdas.

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  • 14. 

    There are times when the number of bits received varies from what is transmitted. Let's say, for example, we receive 9,605 b/s (5 extra). We would need a buffer to store the extra bits. We call this a(n) _______ and, depending on the bit count specifications for the circuit or system, it could cause an alarm to be activated.

    • Overflow

    • Buffer

    • Storage

    • Cache

    Correct Answer
    A. Overflow
    Explanation
    When the number of bits received exceeds what is transmitted, it is referred to as overflow. In this scenario, if we receive 9,605 b/s instead of the expected amount, there would be 5 extra bits that need to be stored. To accommodate these extra bits, a buffer is used. Depending on the specifications of the circuit or system, this overflow condition could trigger an alarm to be activated.

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  • 15. 

    In PAM, the results of this analysis show that a rectangular pulse train contains many frequencies. The frequencies are all multiples of the fundamental frequency of the pulse train, f(o), which is equal to the reciprocal of the period, T(p), of the wave and expressed by the equation: f(o) = 1 / T(p).

    • Fourier Analysis

    • Johnson Analysis

    • Einstein Analysis

    • Douglas Analysis

    Correct Answer
    A. Fourier Analysis
    Explanation
    The given explanation states that in PAM (Pulse Amplitude Modulation), the analysis of a rectangular pulse train reveals that it contains multiple frequencies. These frequencies are all multiples of the fundamental frequency of the pulse train, which is equal to the reciprocal of the period of the wave. This concept is known as Fourier Analysis, which is a mathematical technique used to decompose a complex waveform into its constituent frequencies. Therefore, the correct answer is Fourier Analysis.

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  • 16. 

    What term do we use for the additional sidebands that cause unwanted bandwidth and distortion in the transmitted AM signal?

    • Splatter

    • Noise

    • Emanations

    • Bad Sidebands

    Correct Answer
    A. Splatter
    Explanation
    Splatter refers to the additional sidebands that cause unwanted bandwidth and distortion in the transmitted AM signal. These sidebands can result from various factors such as nonlinearities in the transmitter, improper modulation, or interference. Splatter can lead to poor signal quality and interference with other nearby frequencies, affecting the overall performance of the transmission.

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  • 17. 

    In ____, the amplitude of the modulated wave does not change---only the frequency is varied.

    • Frequency Modulation

    • Amplitude Modulation

    • Phase Modulation

    • Varied Modulation

    Correct Answer
    A. Frequency Modulation
    Explanation
    Frequency modulation (FM) is a type of modulation in which the frequency of the carrier wave is varied according to the amplitude of the modulating signal. In FM, the amplitude of the modulated wave remains constant while only the frequency changes. This means that as the amplitude of the modulating signal increases, the frequency of the carrier wave also increases, and vice versa. FM is commonly used in radio broadcasting as it provides better noise immunity and signal quality compared to other modulation techniques.

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  • 18. 

    With quantizing, the coded amplitude values are defined as steps of equal amplitude range, the quantizing is said to be ______.

    • Uniform

    • Equal

    • Independent

    • Non-Variable

    Correct Answer
    A. Uniform
    Explanation
    When the coded amplitude values are defined as steps of equal amplitude range, the quantizing is said to be uniform. This means that the intervals between each step are the same, resulting in a consistent and evenly spaced quantization of the amplitude values. This allows for easier interpretation and analysis of the quantized data.

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  • 19. 

    Which of these is not a form of analog modulation?

    • Frequency Modulation

    • Phase Modulation

    • Amplitude Modulation

    • Bandwidth Modulation

    Correct Answer
    A. Bandwidth Modulation
    Explanation
    Bandwidth modulation is not a form of analog modulation because it does not involve varying any of the fundamental properties of the carrier signal, such as its frequency, phase, or amplitude. Instead, bandwidth modulation refers to the process of varying the width of the frequency band that is used to transmit the signal. In other words, it involves changing the range of frequencies that are allowed to pass through a filter or channel, rather than directly manipulating the carrier signal itself.

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  • 20. 

    In DPSK, information is not represented by an absolute phase value but by a _______ in phase value.

    • Change

    • Jump

    • Reverse

    • Timing Source

    Correct Answer
    A. Change
    Explanation
    In DPSK (Differential Phase Shift Keying), information is represented by a change in phase value rather than an absolute phase value. This means that instead of directly encoding the phase of the signal, DPSK encodes the difference in phase between consecutive symbols. By detecting these changes in phase, the receiver can decode the transmitted information. Therefore, the correct answer is "Change" as it accurately describes how information is represented in DPSK.

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  • 21. 

    What is a digital signal that uses three voltage levels to represent data?

    • Tri

    • Ternary

    • Triple

    • Three

    Correct Answer
    A. Ternary
    Explanation
    A digital signal that uses three voltage levels to represent data is called ternary. In this encoding scheme, the signal can take on three different voltage levels, typically representing 0, 1, and a third value that can be used for error checking or other purposes. Ternary signaling allows for more efficient use of bandwidth compared to binary signaling, as it can transmit more information per unit of time.

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  • 22. 

    What uses four different carrier phases (0 degrees, 90 degrees, 180 degrees, and 270 degrees) to represent two data transmission bits. For example, to send 00, the phase changes by 0 degrees.

    • Differential Phase-Shift Keying(DPSK)

    • Binary Phase-Shift Keying(BPSK)

    • Quadrature Phase-Shift Keying(QPSK)

    • Phase Shift Keying(PSK)

    Correct Answer
    A. Quadrature Phase-Shift Keying(QPSK)
    Explanation
    Quadrature Phase-Shift Keying (QPSK) is the correct answer because it uses four different carrier phases (0 degrees, 90 degrees, 180 degrees, and 270 degrees) to represent two data transmission bits. Each phase shift represents a different combination of bits, allowing for efficient data transmission. This modulation scheme is commonly used in digital communication systems to achieve higher data rates while conserving bandwidth.

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  • 23. 

    What varies one or more parameters of a pulse according to a modulating signal to transmit the desired information?

    • Pulse Modulation

    • Phase Modulation

    • Frequency Modulation

    • Amplitude Modulation

    Correct Answer
    A. Pulse Modulation
    Explanation
    Pulse Modulation is the correct answer because it involves varying one or more parameters of a pulse according to a modulating signal to transmit the desired information. This modulation technique is commonly used in digital communication systems to encode and transmit digital data. By varying the parameters of the pulse, such as its amplitude, duration, or position, the information can be encoded and transmitted in the form of pulses.

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  • 24. 

    What is a unit of information based on two symbols, states, or conditions? Remember in technical school, they defined ______ as being the smallest amount of useful information.

    • Datagram

    • Packet

    • Frame

    • Bit

    Correct Answer
    A. Bit
    Explanation
    A bit is a unit of information based on two symbols, states, or conditions. In technical school, it is defined as the smallest amount of useful information.

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  • 25. 

    What is a combination of AM and PM? We use this to convert a digital signal to analog form by varying the amplitude and phase of the carrier signal. Using this method of modulation you are able to encode up to four data bits for transmission. This is also similar to QPSK.

    • Dual Modulation(DM)

    • Combined Modulation(CM)

    • Quadrature Amplitude Modulation(QAM)

    • AM-PM Modulation(AMPMM)

    Correct Answer
    A. Quadrature Amplitude Modulation(QAM)
    Explanation
    Quadrature Amplitude Modulation (QAM) is a combination of AM (Amplitude Modulation) and PM (Phase Modulation). It is used to convert a digital signal to analog form by varying the amplitude and phase of the carrier signal. QAM allows for the encoding of up to four data bits for transmission, making it an efficient modulation technique. QAM is also similar to QPSK (Quadrature Phase Shift Keying), another modulation scheme that encodes data by varying the phase of the carrier signal.

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  • 26. 

    ________ is the simultaneous transmission of several separate information channels over the same communications circuit without interface.

    • Multiplexing

    • Modulation

    • Trunking

    • Companding

    Correct Answer
    A. Multiplexing
    Explanation
    Multiplexing is the correct answer because it refers to the technique of combining multiple signals or data streams into a single transmission medium, such as a communication circuit, without causing interference or overlap. This allows for efficient use of the available bandwidth and enables simultaneous transmission of multiple information channels. Modulation is the process of modifying a carrier signal to carry information, but it does not specifically address the simultaneous transmission of separate channels. Trunking is a method of sharing a communication channel among multiple users, but it does not guarantee interference-free transmission. Companding is a technique used in audio signal processing and does not directly relate to the simultaneous transmission of separate information channels.

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  • 27. 

    What is the conversion of an analog signal into a digital signal? This is done by converting an analog wave into discrete pulses, taking multiple samples, and converting the samples into a digital signal.

    • Digital Modulation

    • Phase Modulation

    • Discrete Pulse Modulation

    • Sample Modulation

    Correct Answer
    A. Digital Modulation
    Explanation
    The correct answer is Digital Modulation. The process of converting an analog signal into a digital signal involves converting the continuous analog wave into discrete pulses. This is done by taking multiple samples of the analog signal at regular intervals and then converting these samples into a digital signal. Digital modulation is the technique used to achieve this conversion, where the discrete pulses are encoded and modulated to represent the original analog signal in a digital format.

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  • 28. 

    _____ is a complete digitization process since it converts an analog signal into one that is discrete with respect to both time and amplitude (or polarity). The signal is based on an analog signal that has already been modulated (by using PAM, PDM, or PPM).

    • Pulse-code Modulation

    • Pre-modulated Modulation

    • Analog Modulation

    • Complete Modulation

    Correct Answer
    A. Pulse-code Modulation
    Explanation
    Pulse-code Modulation (PCM) is the correct answer because it is a complete digitization process that converts an analog signal into a discrete signal in terms of both time and amplitude. PCM is used when the analog signal has already been modulated using techniques like PAM (Pulse Amplitude Modulation), PDM (Pulse Duration Modulation), or PPM (Pulse Position Modulation). PCM samples the analog signal at regular intervals and quantizes the amplitude of each sample, resulting in a digital representation of the original analog signal.

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  • 29. 

    What is a digital signal that has two voltage levels?

    • Binary Signal

    • Ternary Signal

    • Dual Signal

    • Double Signal

    Correct Answer
    A. Binary Signal
    Explanation
    A digital signal that has two voltage levels is called a binary signal. In binary signaling, there are only two possible states, typically represented as 0 and 1, or low and high voltage levels. This type of signal is commonly used in digital communication systems, computers, and electronic devices to represent and transmit information. The binary nature of the signal allows for efficient and reliable data transmission and processing.

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  • 30. 

    _____________ does as its name implies. The frequency spectrum is divided into 4 KHz increments, and, by means of multiplexing, many voice-frequency channels can be placed within the frequency spectrum. _______ combines more than one continuous audio signal into a single bandwidth or "group" for transmission.

    • Frequency Division Multiplexing (FDM)

    • Time Division Multiplexing (TDM)

    • Wave Division Multiplexing (WDM)

    • Amplitude Division Multiplexing (ADM)

    Correct Answer
    A. Frequency Division Multiplexing (FDM)
    Explanation
    Frequency Division Multiplexing (FDM) divides the frequency spectrum into 4 KHz increments and uses multiplexing to place multiple voice-frequency channels within the spectrum. This allows for the combination of multiple continuous audio signals into a single bandwidth or "group" for transmission. FDM is an effective technique for optimizing the use of the frequency spectrum and maximizing the capacity for transmitting multiple signals simultaneously.

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  • 31. 

    ______ encodes different digital values as changes in signal phase. This is easier to implement and is more robust than PSK because____ looks for differences, rather than specific values. This form of modulation can be found in local area network technologies.

    • Differential Phase-Shift Keying(DPSK)

    • Phase-Shift Keying(PSK)

    • Binary Phase-Shift Keying(BPSK)

    • Quadrature Phase-Shift Keying(QPSK)

    Correct Answer
    A. Differential Phase-Shift Keying(DPSK)
    Explanation
    Differential Phase-Shift Keying (DPSK) encodes different digital values as changes in signal phase. This is easier to implement and more robust than PSK because DPSK looks for differences, rather than specific values. In DPSK, the receiver only needs to detect whether the phase has changed or not, rather than determining the exact phase value. This makes DPSK more resistant to noise and other interference. DPSK is commonly used in local area network technologies.

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  • 32. 

    In FM, who establishes the amount of deviation?

    • Federal Communications Commission

    • The user

    • The deviation necessary to complete the modulation

    • Government

    Correct Answer
    A. Federal Communications Commission
    Explanation
    The Federal Communications Commission (FCC) establishes the amount of deviation in FM. The FCC is a government agency responsible for regulating communication technologies, including radio broadcasting. In the context of FM modulation, deviation refers to the maximum amount by which the carrier frequency can vary from its original frequency. The FCC sets standards and guidelines for FM broadcasting, including the maximum allowable deviation, to ensure that radio signals are transmitted within the allocated frequency spectrum and do not interfere with other radio services.

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  • 33. 

    The two main reasons for _________, despite its complexity, are as follows: 1. A ______ signal is not as seriously degraded as a bi-phase signal when passed through a nonlinear device simultaneously with interference. 2. The RF bandwidth for a _____ signal is half that required by a bi-phase signal, given the same data rate. Alternatively, twice as much data might be transmitted in the same bandwidth with a ______ signal as with a bi-phase signal.

    • Quadriphase (QPSK)

    • Frequency Modulation (FM)

    • Amplitude Modulation (AM)

    • Phase Modulation (PM)

    Correct Answer
    A. Quadriphase (QPSK)
    Explanation
    The two main reasons for choosing Quadriphase (QPSK), despite its complexity, are as follows:

    1. A QPSK signal is not as seriously degraded as a bi-phase signal when passed through a nonlinear device simultaneously with interference. This means that QPSK is more robust and can handle interference better than bi-phase signals.

    2. The RF bandwidth for a QPSK signal is half that required by a bi-phase signal, given the same data rate. Alternatively, twice as much data might be transmitted in the same bandwidth with a QPSK signal as with a bi-phase signal. This means that QPSK is more efficient in terms of bandwidth utilization and allows for higher data transmission rates.

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  • 34. 

    What are a set structure in which data is placed so data from different channels can be combined at one end of the communications link and taken apart at the other end with each character going to its proper port? The exact structure of this is dependent on aggregate rates and the number and rates of the individual ports.

    • Frames

    • Packets

    • Octets

    • Addresses

    Correct Answer
    A. Frames
    Explanation
    Frames are a set structure in which data is placed so that data from different channels can be combined at one end of the communications link and taken apart at the other end. Each character in the frame is directed to its proper port based on the aggregate rates and the number and rates of the individual ports. Frames provide a standardized format for transmitting data over a network, ensuring that the data is organized and can be correctly received and interpreted by the receiving end.

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  • 35. 

    What is the process, or result of the process, of modifying any characteristic of an information singal or carrier signal so that it varies in step with the instantaneous value of another information signal?

    • Multiplexing

    • Modulation

    • Conversion

    • Manipulating

    Correct Answer
    A. Modulation
    Explanation
    Modulation is the process of modifying a characteristic of an information signal or carrier signal so that it varies in step with the instantaneous value of another information signal. This allows for the transmission of information through different mediums, such as radio waves or optical fibers. Modulation is essential in telecommunications and broadcasting systems as it enables the efficient and reliable transfer of data.

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  • 36. 

    ____ is the simplest form of Phase Modulation. There are two phase shifts (0 degrees or 180 degrees) for data transmission depending on whether a binary 1 or 0 is to be transmitted.

    • Phase Shift Keying(PSK)

    • Differential Phase-Shift Keying(DPSK)

    • Quadrature Phase-Shift Keying(QPSK)

    • Binary Phase-Shift Keying(BPSK)

    Correct Answer
    A. Binary Phase-Shift Keying(BPSK)
    Explanation
    Binary Phase-Shift Keying (BPSK) is the simplest form of Phase Modulation. In BPSK, there are two phase shifts (0 degrees or 180 degrees) for data transmission depending on whether a binary 1 or 0 is to be transmitted. This means that the carrier signal is shifted in phase by either 0 degrees or 180 degrees to represent the binary data. BPSK is widely used in various communication systems due to its simplicity and robustness against noise.

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  • 37. 

    In Amplitude Modulation, we can show the output of the modulation that contain the following frequencies. Which of these is not an output?

    • F(c)

    • F(c) + F(m)

    • F(c) - F(m)

    • F(c) x F(m)

    Correct Answer
    A. F(c) x F(m)
    Explanation
    In Amplitude Modulation, the output of the modulation contains the sum (F(c) + F(m)) and the difference (F(c) - F(m)) of the carrier frequency (F(c)) and the modulating frequency (F(m)). However, the product (F(c) x F(m)) is not an output in Amplitude Modulation.

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  • 38. 

    In complex Amplitude Modulation, this sideband has the same shape and orientation as the band of modulating signal frequencies.

    • Upper Sideband(USB)

    • Lower Sideband(LSB)

    • Frequency Sideband(FSB)

    • Amplitude Sideband(ASB)

    Correct Answer
    A. Upper Sideband(USB)
    Explanation
    In complex Amplitude Modulation, the upper sideband (USB) has the same shape and orientation as the band of modulating signal frequencies. This means that the USB contains the same frequencies as the modulating signal, but shifted to higher frequencies. In complex AM, the modulating signal is multiplied by a carrier signal and the resulting signal is composed of the carrier frequency, the upper sideband, and the lower sideband. Since the USB has the same shape and orientation as the modulating signal, it carries the same information as the original signal but at higher frequencies.

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  • 39. 

    In complex Analog Modulation, this sideband is the mirror image of the original modulating signal. This sideband is said to be inverted, since its shape is the reverse of the modulating signal.

    • Lower Sideband(LSB)

    • Upper Sideband(USB)

    • Frequency Sideband(FSB)

    • Amplitude Sideband(ASB)

    Correct Answer
    A. Lower Sideband(LSB)
    Explanation
    In complex Analog Modulation, the lower sideband (LSB) is the mirror image of the original modulating signal. This means that the shape of the lower sideband is the reverse of the modulating signal.

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  • 40. 

    We can express the 6-to-1 improvement of SSBSC over DSBSC as __ decibels (dB) of improvement.

    • 8

    • 6

    • 4

    • 2

    Correct Answer
    A. 8
    Explanation
    The 6-to-1 improvement of SSBSC over DSBSC can be expressed as 8 decibels (dB) of improvement.

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  • 41. 

    The capability for regeneration of quantized pulses can be further enhanced by ________ the pulses to make them of constant duration and amplitude before transmission. This helps the signal to be recognized so it can be reproduced---whether the pulse is received or not.

    • Coding

    • Assistance

    • Helping

    • Changing

    Correct Answer
    A. Coding
    Explanation
    The capability for regeneration of quantized pulses can be further enhanced by coding the pulses to make them of constant duration and amplitude before transmission. This coding process helps in ensuring that the signal can be recognized and reproduced accurately, regardless of whether the pulse is received or not.

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  • 42. 

    _______ frames are used for rates below 384.2 kbps and is composed of a number of 8 bit slots with each slot holding one character.

    • Low Speed

    • High Speed

    • Fast

    • Slow

    Correct Answer
    A. Low Speed
    Explanation
    Low Speed frames are used for rates below 384.2 kbps and are composed of a number of 8 bit slots, with each slot holding one character. This means that Low Speed frames are designed for slower transmission rates and are capable of transmitting one character at a time.

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  • 43. 

    ________ is an expression of time of the shortest unit duration. Bit, on the other hand, carries no suggestion of time; it expresses the number of information pulses in one second, but it tells nothing about their duration.

    • Bit

    • Baud

    • Signaling Rate

    • Rate of Modulation

    Correct Answer
    A. Baud
    Explanation
    Baud is a unit of measurement that represents the number of signal changes per second in a communication channel. It is used to measure the rate of transmission of information, specifically in terms of the number of signal elements per second. Unlike bit, which only quantifies the number of information pulses in one second, baud also takes into account the duration of these pulses. Therefore, baud is a more comprehensive measure of the rate of transmission in a communication system.

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  • 44. 

    The pulses of PCM are grouped into any of a predefined number of different levels using a ______; each of the possible levels is represented by a unique bit stream. The number of possible values in this stream determines the granularity of the modulation.

    • Quantizer

    • Compander

    • Transformer

    • Converter

    Correct Answer
    A. Quantizer
    Explanation
    In PCM (Pulse Code Modulation), the pulses are grouped into different levels using a quantizer. The quantizer assigns each pulse to a specific level, and each level is represented by a unique bit stream. The number of possible values in this bit stream determines the granularity or resolution of the modulation. A higher number of possible values allows for more precise representation of the signal, while a lower number of values reduces the precision but requires less bandwidth. Therefore, the correct answer is "Quantizer".

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  • 45. 

    The ______ of a pulse train is determined only by the width of the pulse, not by its frequency. The frequency determines the number or the spacing of the ________.

    • Bandwidth, Harmonics

    • Harmonics, Bandwidth

    • Speed, Size

    • Size, Speed

    Correct Answer
    A. Bandwidth, Harmonics
    Explanation
    The bandwidth of a pulse train refers to the range of frequencies that the pulse train contains. It is determined by the width of the pulse, as a wider pulse will contain a wider range of frequencies. On the other hand, harmonics refer to the multiple frequencies that are integer multiples of the fundamental frequency. The frequency of the pulse train determines the number or spacing of these harmonics. Therefore, the correct answer is "Bandwidth, Harmonics."

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  • 46. 

    T1 uses the _____ process. These inputs can be a combination of digital, video, and audio signals. The input signals are multiplexed into a serial output, which consists of twenty-four 8-bit words and one framing bit used to maintain control and synchronization.

    • FDM

    • ADM

    • WDM

    • TDM

    Correct Answer
    A. TDM
    Explanation
    T1 uses the TDM (Time Division Multiplexing) process. In TDM, multiple signals are combined into a single stream by dividing the transmission time into smaller time slots. In the case of T1, the input signals, such as digital, video, and audio, are multiplexed into a serial output consisting of twenty-four 8-bit words and one framing bit. This allows for efficient transmission of multiple signals over a single communication channel by allocating each signal its own time slot.

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  • 47. 

    When a signal transition occurs, the signal levels moves to one of the discrete signal levels, but after a predetermined time (normally 50 percent of a bit), it returns to zero voltage. What kind of digital signaling is this?

    • CDI

    • AMI

    • NRZ

    • RZ

    Correct Answer
    A. RZ
    Explanation
    Return to Zero (RZ) is a type of digital signaling where the signal levels move to one of the discrete signal levels during a signal transition, but after a predetermined time (usually 50 percent of a bit), it returns to zero voltage. This means that the signal has distinct positive and negative voltage levels, with a clear zero voltage in between each bit. This type of signaling helps in accurately detecting the start and end of each bit, making it easier for the receiver to synchronize with the sender's signal.

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  • 48. 

    This is another method used for TDM. ____ is also known as pulse-width modulation(PWM), pulse-length modulation(PLM), or pulse-time modulation(PTM). In ____ the pulse duration, or width, of each sample pulse is varied to encode an analog signal at the point of sampling. This method is less affected by noise than the PAM method.

    • Pulse-duration Modulation

    • Pulse-amplitude Modulation

    • Pulse-position Modulation

    • Pulse-code Modulation

    Correct Answer
    A. Pulse-duration Modulation
    Explanation
    Pulse-duration modulation (PDM) is another method used for time-division multiplexing (TDM). PDM is also known as pulse-width modulation (PWM), pulse-length modulation (PLM), or pulse-time modulation (PTM). In PDM, the pulse duration or width of each sample pulse is varied to encode an analog signal at the point of sampling. This method is less affected by noise than the pulse-amplitude modulation (PAM) method.

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  • 49. 

    Binary signals can be either unipolar or polar in nature. This scheme also uses two levels for encoding. The difference is the use of both positive and negative voltages to represent the data. In the example, a -3 volt is a binary 1, while +3 volts is a binary 0.

    • Unipolar

    • Polar

    • Dual

    • Double

    Correct Answer
    A. Polar
    Explanation
    Polar signals use both positive and negative voltages to represent data, while unipolar signals only use one level (either positive or negative). In this example, a -3 volt represents a binary 1, and +3 volts represents a binary 0. Therefore, the correct answer is "Polar" because it accurately describes the encoding scheme being used.

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  • Mar 20, 2023
    Quiz Edited by
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  • Apr 02, 2013
    Quiz Created by
    Esshlman
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