3c251 Volume 1

124 Questions | Total Attempts: 479

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Volume Quizzes & Trivia

3C251 Volume 1. URE's only.


Questions and Answers
  • 1. 
    What is an example of analog to digital and digital to analog techniques?
    • A. 

      Amplitude modulation (AM) and frequency modulation (FM)

    • B. 

      Pulse code modulation (PCM) and frequency shift key modulation (FSK)

    • C. 

      Phase modulation (PM) and quadrature phase shift key (QPSK)

    • D. 

      Pulse code modulation (PCM) and continuously variable slope delta (CVSD) modulation

  • 2. 
    What modulation technique 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)?
    • A. 

      Pulse-amplitude modulation (PAM)

    • B. 

      Pulse-duration modulation (PDM)

    • C. 

      Pulse-width modulation (PWM)

    • D. 

      Pulse-code modulation (PCM)

  • 3. 
    Amplitude modulation (AM) requires a bandwidth that is
    • A. 

      Twice that of the modulating signal

    • B. 

      Half that of the modulation signal

    • C. 

      Twice that of the carrier signal

    • D. 

      Half that of the carrier signal

  • 4. 
    We can express the 6-to-1 improvement of the signal-sideband suppressed carrier (SSBSC) modulation over conventional amplitude modulation (AM) as
    • A. 

      2 decibels (dB) of improvement

    • B. 

      4 dB of improvement

    • C. 

      6 dB of improvement

    • D. 

      8 dB of improvement

  • 5. 
    A modulated waveform that contains a carrier plus two sidebands for each modulation frequency is a description of
    • A. 

      A phase modulation (PM)

    • B. 

      A pulse modulation

    • C. 

      A frequency modulation (FM)

    • D. 

      An amplitude modulation (AM)

  • 6. 
    If 100 percent modulation is exceeded and there is distortion in the modulating signal, additional sidebands are generated.  We identify these sideband as
    • A. 

      Transmitted intelligence

    • B. 

      Intensity of speech

    • C. 

      Composite waves

    • D. 

      Splatter

  • 7. 
    To prevent frequency modulation (FM) radio stations from interfering with each other, the Federal Communications Commission (FCC) has set limits that allow each station to cause its oscillator frequency to deviate no more than
    • A. 

      20 kHz

    • B. 

      50 kHz

    • C. 

      75 kHz

    • D. 

      88 kHz

  • 8. 
    The amount of phase shift in a phase modulation (PM) signal is directly proportional to the
    • A. 

      Modulation index

    • B. 

      Rate of phase shift

    • C. 

      Frequency of the modulating signal

    • D. 

      Amplitude of the modulating signal

  • 9. 
    Quadrature-phase shift keying (QPSK) requires
    • A. 

      Half the bandwidth as does bi-phase shift keying (BPSK)

    • B. 

      The same bandwidth as does BPSK

    • C. 

      Twice the bandwidth as does BPSK

    • D. 

      Four times the bandwidth as does BPSK

  • 10. 
    What is the main advantage of differential phase shift keying (DSPK)?
    • A. 

      Carrier presence is required to detect changes

    • B. 

      It requires a less complex receiver than a basic phase shift keying (PSK) signal

    • C. 

      It requires a more complex receiver than a basic PSK signal

    • D. 

      The demodulator needs to detect changes in absolute phase values

  • 11. 
    All of these are considered analog modulation techniques except
    • A. 

      Pulse-amplitude modulation (PAM)

    • B. 

      Pulse-duration modulation (PDM)

    • C. 

      Pulse-position modulation (PPM)

    • D. 

      Pulse-code modulation (PCM)

  • 12. 
    The form of pulse modulation that requires the pulse width to be varied to convoy intelligence is
    • A. 

      Pulse-amplitude modulation (PAM)

    • B. 

      Pulse-duration modulation (PDM)

    • C. 

      Pulse-position modulation (PPM)

    • D. 

      Pulse-code modulation (PCM)

  • 13. 
    Quantized analog modulation is actually
    • A. 

      Pulse-amplitude modulation (PAM)

    • B. 

      Pulse-duration modulation (PDM)

    • C. 

      Less tolerant of noise than frequency modulation (FM)

    • D. 

      Analog-to-digital conversion

  • 14. 
    Which type of pulse modulation is least affected by noise?
    • A. 

      Pulse-amplitude modulation (PAM)

    • B. 

      Pulse-duration modulation (PDM)

    • C. 

      Pulse-position modulation (PPM)

    • D. 

      Pulse-code modulation (PCM)

  • 15. 
    Pulse-code modulation (PCM) code words are assigned to each sample and correspond to its
    • A. 

      Phase

    • B. 

      Time slot

    • C. 

      Amplitude

    • D. 

      Frequency

  • 16. 
    How many bits per character of a 16-step pulse-code modulation (PCM) system are used to describe the quantized analog sample?
    • A. 

      3

    • B. 

      4

    • C. 

      5

    • D. 

      8

  • 17. 
    The process of coding pulse code modulation (PCM) quantized pulses to make them a constant duration and amplitude is
    • A. 

      Encoding

    • B. 

      Compounding

    • C. 

      Uniform quantizing

    • D. 

      Nonuniform quantizing

  • 18. 
    Noise  in delta modulation (DM) can be reduced by varying the approximation signal step size in accordance with the input signal's
    • A. 

      Speed

    • B. 

      Phase

    • C. 

      Amplitude

    • D. 

      Frequency

  • 19. 
    What modulation technique varies the step size in accordance with the magnitude of the input signal's amplitude?
    • A. 

      Delta modulation (DM)

    • B. 

      Frequency modulation (FM)

    • C. 

      Pulse-code modulation (PCM)

    • D. 

      Continuous variable slope delta modulation (CVSD)

  • 20. 
    Continuous variable slope delta (CVSD) modulation circuitry includes a pulse-amplitude modulator and a
    • A. 

      Low-pass filter

    • B. 

      High-pass filter

    • C. 

      Bandpass filter

    • D. 

      Band-reject filter

  • 21. 
    Which modulation technique was developed to reduce signal loss and noise in a tactical environment?
    • A. 

      Delta modulation (DM)

    • B. 

      Pulse-code modulation (PCM)

    • C. 

      Conditioned diphase interface modulation (CDI)

    • D. 

      Adaptive differential pulse-code modulation (ADPCM)

  • 22. 
    Up to what percentage of speech is redundant?
    • A. 

      35

    • B. 

      45

    • C. 

      65

    • D. 

      75

  • 23. 
    The accepted standard for the voice frequency band is
    • A. 

      300 to 1,600 hertz (Hz)

    • B. 

      300 to 2,600 Hz

    • C. 

      300 to 3,400 Hz

    • D. 

      300 to 3,800 Hz

  • 24. 
    Noise may be introduced into speech signals by thermal agitation and
    • A. 

      Power variations

    • B. 

      Amplitude variations

    • C. 

      Black body radiation

    • D. 

      Molecular breakdown of electronic components

  • 25. 
    Bits are taken from an input channel data stream at a rate at twice the highest frequency appearing in the intelligence signal we call
    • A. 

      The sampling rate

    • B. 

      Pulse-bit stuffing

    • C. 

      Pulse-code modulation (PCM)

    • D. 

      Elastic storage implementation