CDC 3D153 Volume 1 V1 (April 2013)

100 Questions | Total Attempts: 1993

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CDC Quizzes & Trivia

CDC 3D153 01 1206, Edit Code 02 (April 2013) Volume 1 Units 1-5 Unit 1: Communication Principles Unit 2: Protecting Electronic Equipment Unit 3: General Purpose Instruments Unit 4: Radio Frequency Test Equipment Unit 5: Standard Practices


Questions and Answers
  • 1. 
     What is one reason for modulation that 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 categories used to produce modulation in radio frequency (RF) transmission today?
    • A. 

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

    • B. 

      Pulse amplitude, pulse width, and pulse position.

    • C. 

      Amplitude, frequency, and phase.

    • D. 

      Analog, digital, and shift keying.

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

      Modulating signal, upper sideband, and lower sideband.

    • B. 

      Carrier, upper sideband, and lower sideband.

    • C. 

      Upper sideband and modulating signal.

    • D. 

      Carrier and modulating signal.

  • 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, 1 MHz, and 0.99 MHz.

    • B. 

      1.1 MHz, 1 MHz, and 0.9 MHz.

    • C. 

      1.11 MHz, 1 MHz, and 0.99 MHz.

    • D. 

      1.111 MHz, 1 MHz, 0.999 MHz.

  • 5. 
    The bandwidth of an amplitude modulated signal is
    • A. 

      Two times the modulating signal.

    • B. 

      The same as the modulating signal.

    • C. 

      Determined by the modulation index.

    • D. 

      Defined in terms of maximum amount of modulation.

  • 6. 
    Use the formula on page 1-3. If an oscilloscope displays a modulation envelope having an E(max) of 200 volts and an E(min) of 20 volts, what is the modulation percentage?
    • A. 

      81.8.

    • B. 

      85.5.

    • C. 

      88.

    • D. 

      122.

  • 7. 
    Which statement concerning bandwidth is true?
    • A. 

      Overmodulating increases bandwidth because the distortion produces harmonics.

    • B. 

      Undermodulating increases bandwidth because the distortion produces harmonics.

    • C. 

      Overmodulating increases bandwidth because the output's increased amplitude.

    • D. 

      Undermodulating increases bandwidth because the output's decreased amplitude.

  • 8. 
    The output of the oscillator in a frequency modulation (FM) modulator increases in frequency with each...
    • A. 

      Positive half cycle of the carrier.

    • B. 

      Negative half cycle of the carrier.

    • C. 

      Positive half cycle of the modulating signal.

    • D. 

      Negative half cycle of the modulating signal.

  • 9. 
    In frequency modulation, a significant sideband contains at least what percentage of the total transmitted power?
    • A. 

      1.

    • B. 

      3.

    • C. 

      10.

    • D. 

      0.1.

  • 10. 
    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.

  • 11. 
    A 5 kHz modulating signal has enough peak voltage to cause a deviation of 15 kHz. What is the modulation index?
    • A. 

      5.

    • B. 

      0.5.

    • C. 

      0.3.

    • D. 

      3.

  • 12. 
    What is it called when a narrow frequency band between adjacent stations prevent frequency modulated sidebands from overlapping?
    • A. 

      Space.

    • B. 

      Guard band.

    • C. 

      Buffer zone.

    • D. 

      Prevention field.

  • 13. 
    In phase modulation, what part of the carrier signal is varied?
    • A. 

      Frequency.

    • B. 

      Amplitude.

    • C. 

      Height.

    • D. 

      Phase.

  • 14. 
    In phase modulation, the carrier's
    • A. 

      Phase is shifted at the rate of the modulating signal.

    • B. 

      Phase shifted with the phase of the modulating signal.

    • C. 

      Amplitude is shifted at the rate of the modulating signal.

    • D. 

      Amplitude is shifted with the phase of the modulating signal.

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

      Discrete amplitudes are assigned to the sampling pulses.

    • B. 

      A binary code number is assigned to the sample.

    • C. 

      The quantizer limits the amplitude of the pulses.

    • D. 

      The analog signal is band limited.

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

      Sampling.

    • B. 

      Rectifying.

    • C. 

      Oscillating.

    • D. 

      Band limiting.

  • 17. 
    In asynchronous transmissions, what bit is used by the receiving device to verify that the transmission was received correctly?
    • A. 

      Control.

    • B. 

      Parity.

    • C. 

      Start.

    • D. 

      Stop.

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

      One character.

    • B. 

      Block of data.

    • C. 

      A parity bit.

    • D. 

      A stop bit.

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

      Determines parity.

    • B. 

      Determines transmission rate.

    • C. 

      Determines whether transmission is in ASCII format.

    • D. 

      Determines whether transmission is synchronous or asynchronous.

  • 20. 
    What error detection method is used for checking a data block greater than 512 and is about 99 percent effective in most applications?
    • A. 

      Checksum.

    • B. 

      Cyclic redundancy check.

    • C. 

      Vertical redundancy check.

    • D. 

      Longitudinal redundancy check.

  • 21. 
    When using forward error control as a method of error correction, where does error correction take place?
    • A. 

      Receiving end.

    • B. 

      In the oscillator.

    • C. 

      Transmitting end.

    • D. 

      In the primary buffers.

  • 22. 
    Light sources that are applicable to fiber optic waveguide are light-emitting diodes and
    • A. 

      Photo transistors.

    • B. 

      Hybrid photodiodes.

    • C. 

      Semiconductor laser diodes.

    • D. 

      Integrated photodiode/preamplifiers.

  • 23. 
    What type of light is emitted from a laser?
    • A. 

      Incoherent.

    • B. 

      Coherent.

    • C. 

      Ordinary.

    • D. 

      Invisible.

  • 24. 
    What are the two main types of photodetectors?
    • A. 

      Positive intrinsic negative and avalanche photodiode.

    • B. 

      Light-emitting diode and avalanche photodiode.

    • C. 

      Light emitting diode and semiconductor laser.

    • D. 

      Tunnel and zener diodes.

  • 25. 
    What photo detector converts one photon to one electron?
    • A. 

      Light emitting diode.

    • B. 

      Avalanche photodiode.

    • C. 

      Positive intrinsic negative diode.

    • D. 

      Integrated photodiode/preamplifier.

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