3D153 V1

100 Questions | Total Attempts: 730

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3D153 Quizzes & Trivia

Cdc 3D153 volume 1 ure


Questions and Answers
  • 1. 
    What reason for modulation involves modulating low frequency signals for transmission over long distances?
    • A. 

      Spectrum conservation

    • B. 

      Channel allocation

    • C. 

      Ease of radiation

    • D. 

      Companding

  • 2. 
    What are the three general catergories used to produce modulation in radio frequency (RF) transmission today?
    • A. 

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

    • B. 

      Pulse amplitude, pulse width, and pulse postion

    • C. 

      Amplitude, frequency, phase

    • D. 

      Analog, digital, and shift keying

  • 3. 
    When the modulating signal and carrier signal are combined within a modulator, the ouput signal contains a/an
    • A. 

      Modulating signal, upper sideband, lower sideband

    • B. 

      Carrier, upper sideband, lower sideband

    • C. 

      Upper sideband and modulating signal

    • D. 

      Carrier and modulating signal

  • 4. 
    If a carrier frequency of 1 MHz and a modulating tone of 10 KHz goes to the modulator, the output signal include
    • A. 

      1.01 MHz, 1MHz, 0.99 MHz

    • B. 

      1.1 MHz, 1 MHz, 0.9 MHz

    • C. 

      1.11 MHz, 1 MHz, 0.99 MHz

    • D. 

      1.111 MHz, 1 MHz, 0.999 MHz

  • 5. 
    If the modulating audio signal is 10 KHz wide, what is the bandwidth of the transmitted ampiltude modulated signal?
    • A. 

      5 KHz

    • B. 

      10 KHz

    • C. 

      15 KHz

    • D. 

      20 KHz

  • 6. 
    The bandwith of an amplitude modulated signal is
    • A. 

      Two times the modulated signal

    • B. 

      The same as the modulated signal

    • C. 

      Determined by the the modulating index

    • D. 

      Defined in terms of maximum amount of modulation

  • 7. 
    The amount of effect or change that the intelligence has on the carrier in an amplitude modulated signal is expressed as the
    • A. 

      Percent of modulation

    • B. 

      Modulation index

    • C. 

      Bandwidth

    • D. 

      Deviation

  • 8. 
    Which statement concerning bandwith is true?
    • A. 

      Overmodulating increases bandwith due to the production of harmonics

    • B. 

      Undermodulating increases bandwith due to the production of harmonics

    • C. 

      Overmodulating increases bandwith due to the output's increased amplitude

    • D. 

      Undermodulating increases bandwith due to the output's decreased amplitude

  • 9. 
    Reducing modulation to less than 100 percent gives
    • A. 

      More total power

    • B. 

      A reduction in carrier power

    • C. 

      No reduction in carrier power

    • D. 

      A reduction in carrier and sideband power

  • 10. 
    In frequency modulation (FM), the amount of oscillator frequency change is
    • A. 

      Inversely proportional to the amplitude of the modulating signal

    • B. 

      Directly proportional to the amplitude of the modulating signal

    • C. 

      Inversely proportional to the phase of the modulating signal

    • D. 

      Directly proportional to the phase of the modulating signal

  • 11. 
    In frequency modulation (FM), what is considered a significant sideband?
    • A. 

      Sidebands containing at least 1 percent of the total transmitted power

    • B. 

      Sidebands containing at least 3 percent of the total transmitted power

    • C. 

      Sidebands containing at least 10 percent of the total transmitted power

    • D. 

      Sidebands containing at least 0.1 percent of the total transmitted power

  • 12. 
    What is the formula to find the modulating index?
    • A. 

      Deviation divided by frequency of modulation

    • B. 

      Deviation times frequency of modulation

    • C. 

      Sideband divide by carrier frequency

    • D. 

      Sideband times carrier frequency

  • 13. 
    In phase modulation (PM), the carrier's
    • A. 

      Phase is shifted at the rate of the modulating signal

    • B. 

      Phase is shifted with the phase of the modulating signal

    • C. 

      Amplitude is shifted at the rate of the modulating signal

    • D. 

      Amplitude is shifted with the phase of the modulating signal

  • 14. 
    What is the advantage of adding more phase shifts?
    • A. 

      Easier detection

    • B. 

      Smaller bit error rate

    • C. 

      Better signal-to-noise ratio

    • D. 

      Higher data rates within a given bandwith

  • 15. 
    What is the first step in pulse code modulation (PCM) process?
    • A. 

      Discrete amplitudes are assigned to the sampling pulses

    • B. 

      A binary code number is assigned to the sample

    • C. 

      The quantizer limits the amplitude of the pulses

    • D. 

      The analog signal is band-limited

  • 16. 
    What part of the pulse code modulation (PCM) process converts a continuous time signal into a discrete time signal?
    • A. 

      Sampling

    • B. 

      Rectifying

    • C. 

      Oscillating

    • D. 

      Band limiting

  • 17. 
    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
    • A. 

      Pulse width modulation (PWM)

    • B. 

      Pulse postion modulation

    • C. 

      Pulse duration modulaton

    • D. 

      Pulse amplitude modulation

  • 18. 
    If an error should occur, what data transmission is lost in a synchronous transmission?
    • A. 

      One character

    • B. 

      Block of data

    • C. 

      A parity bit

    • D. 

      Sychronization (SYNC) bit

  • 19. 
    When using vertical redundancy check (VRC), what significance does the amount of ones have in a data bit pattern?
    • A. 

      Determines parity

    • B. 

      Determines transmission rate

    • C. 

      Determines whether transmission is in American Stadard code for Information Interchange (ASCII) format

    • D. 

      Determines whether transmission is sychronous or asynchronous

  • 20. 
    What two error dectection methods, when used together, are 98 percent effective in detecting errors?
    • A. 

      Checksum and cyclic redundancy check

    • B. 

      Longitundinal redundancy check and checksum

    • C. 

      Cyclic redundancy chack and vertical redundancy check

    • D. 

      Vertical redundancy check and longitundinal redundancy check

  • 21. 
    What error detection method adds stacked characters, divides it by 255, and disregards the answer except for the remainder?
    • A. 

      Checksum

    • B. 

      Block check character

    • C. 

      Cyclic redundancy check

    • D. 

      Vertical redundancy check

  • 22. 
    What error-correction technique send a retransmittal request by the reciever to the sender if it finds an error in a recieved frame?
    • A. 

      Error-correcting code

    • B. 

      Forward error control

    • C. 

      Redundant data transfer

    • D. 

      Automatic retransmit on request

  • 23. 
    When using forward error control as a method of error correction, where does error correction take place?
    • A. 

      Recieving end

    • B. 

      In the oscillator

    • C. 

      Transmitting end

    • D. 

      In the primary buffers

  • 24. 
    What does an optical source do?
    • A. 

      Terminates fiber optics cable

    • B. 

      Converts electrical energy into optical energy

    • C. 

      Extends the distance and to preserve signal integrity

    • D. 

      Accepts optical signals and converts them into electrical signals

  • 25. 
    Light sources that are applicable to fiber optic waveguide are light-emitting diodes (LED) and
    • A. 

      Photo transistors

    • B. 

      Hybrid photodiodes

    • C. 

      Semiconductor laser diodes

    • D. 

      Integrated photodiode preamplifiers