3D153 Vol 1 Unit 1

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  1. what reason for modulation involves modulating low frequency signals for transmission over long distances?
    Ease of radiation
  2. What are the three general categories used to produce modulation in radio frequency (RF) transmission today?
    amplitude, frequency, and phase
  3. when the modulating signal and carrier signal are combined within a modulator, the output signal contains a/an
    carrier, upper sideband, and lower sideband
  4. if a carrier frequency of 1 MHz and a modulating tone of 10 kHz goes to the modulator, the output signal include
    1.01 MHz, 1 MHz, and .99 MHz
  5. If the modulating audio signal is 10 kHz wide, what is the bandwidth of the transmitted amplitude modulated signal?
    20 kHz
  6. the bandwidth of an amplitude modulated signal is
    two times the modulating signal
  7. the amount of effect or change that the intelligence has on the carrier in an amplitude modulated signal is expressed as the
    percent of modulation
  8. which statement concerning bandwidth is true?
    overmodulating increases bandwidth due to the production of harmonics
  9. reducing modulation to less than 100 percent gives
    no reduction in carrier power
  10. in frequency modulating (FM), what is considered a significant sideband?
    sidebands containing at least 1 percent of the total transmitted power
  11. what is the formula to find the modulating index?
    deviation divided by frequency of modulation
  12. in phase modulation (PM) the carrier's
    phase is shifted at the rate of the modulating signal
  13. what is the advantage of adding more phase shifts
    higher data rates within a given bandwidth
  14. what is the first step in the pulse code modulation process?
    the analog signal is band-limited
  15. what part of the pulse code modulation (PCM) process converts a continuous time signal into a discrete time signal?
  16. 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
    pulse amplitude modulation
  17. if an error should occur, what data transmission is lost in a synchronous transmission?
    block of data
  18. when using vertical redundancy check ( VRC), what significance does the amount of ones have in a data bit pattern?
    determines parity
  19. what two error detection methods, when used together, are 98 percent effective in detecting errors?
    vertical redundancy check and longitudinal redundancy check
  20. what error detection method adds stacked characters, divides it by 255, and disregards the answer except for the remainder?
  21. what error-correction technique sends a retransmittal request by the receiver to the sender if it finds an error in a received frame?
    automatic retransmit on request
  22. when using forward error control as a method of error correction, where does error correction take place?
    receiving end
  23. what does an optical source do?
    converts electrical energy into optical energy
  24. light sources that are applicable to fiber optic waveguide are light-emitting diodes (LED) and
    semiconductor laser diodes
  25. what type of light is emitted from a laser
  26. laser diode power coupling is measured in which range?
  27. a device that accepts optical signals from an optical fiber and converts them into electrical signals is called an optical
  28. small current that flows from a photodiode even with no light is called
    dark current
  29. the responsivity of a photo detector is dependent on the
    signal-to-noise ratio (SNR)
  30. What are the two main types of photodetectors?
    positive intrinsic negative and avalanche photodiode.
  31. what photo detector converts one photon to one electron?
    positive intrinsic negative (PIN) diode
  32. what is used to extend the distance of a fiber optic communication systems link?
  33. which repeater amplifies optical signal without converting to and from the electrical domain?
    optical amplifiers
  34. short sections of single fiber cables that has a connector at each end is called a
    patch cord
  35. which fiber-optic connector uses quick-release, keyed bayonet couplings that are preferred in situations where severe vibrations are not expected?
    straight tip (ST)
  36. Which fiber optic connector uses a push-pull engagement for mating?
    subscriber (SC)
Card Set
3D153 Vol 1 Unit 1
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