3D153 CDC Volume 1

37 Questions | Total Attempts: 418

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3D153 Quizzes & Trivia

Radio Frequency Transmission Systems Journeyman Volume 1


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 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/an  
    • A. 

      Modulating signal, upper sideband, 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 .99 MHz

    • B. 

      1.1 MHz, 1 MHz, and .9 MHz

    • C. 

      1.11 MHz, 1 MHz, .99 MHz

    • D. 

      1.111 MHz, 1 MHz, .999 MHz

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

      5 kHz

    • B. 

      10 kHz

    • C. 

      15 kHz

    • D. 

      20 kHz

  • 6. 
     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 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 bandwidth is true? 
    • A. 

      Overmodulating increases bandwidth due to the production of harmonics.

    • B. 

      Undermodulating increases bandwidth due to the production of harmonics.

    • C. 

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

    • D. 

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

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

      More total power

    • B. 

      A reduction to 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. 

      Durectly 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 divided 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 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 bandwidth

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

      Discrete amplitudes are assigned to the sampling pulse

    • B. 

      A binary code number is assigned to the smaple.

    • 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 position modulation

    • C. 

      Pulse duration modulation

    • 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. 

      Synchcroniztion (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 Standard code for Information Interchange (ASCII) format

    • D. 

      Determines whether transmission is synchronous or asynchronous

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

      Checksum and cyclic redundancy checkin

    • B. 

      Longitudinal redundancy check and checksum

    • C. 

      Cyclic redundancy check and vertical redundancy check

    • D. 

      Vertical redundancy check and longitudinal 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 sends a retransmittal request by the receiver to the sender if it finds an error in a received 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. 

      Receiving end

    • B. 

      In the oscillator

    • C. 

      Transmitting end

    • D. 

      In the primary buffers

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

      Terminates fiber optic cables

    • B. 

      Converts electrical energy into optical energy

    • C. 

      Extend 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