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ECE :: Communication Systems

  1. If a signal band limited for fm is sampled at a rate less than 2 fm the reconstructed signal will be

  2. A.
    smaller in amplitude
    B.
    distorted
    C.
    having higher frequencies suppressed
    D.
    none of the above

  3. A better SNR can be obtained in a PCM by

  4. A.
    increasing sampling rate above Nyquist rate
    B.
    decreasing the code bits
    C.
    reducing channel bandwidth
    D.
    increasing Quantization levels

  5. The baud rate is

  6. A.
    always equal to the bit transfer rate
    B.
    equal to twice the bandwidth of an ideal channel
    C.
    not equal to the signalling rate
    D.
    equal to one half the bandwidth of ideal channel

  7. The type of noise that interfere very much with high frequency transmission is

  8. A.
    white
    B.
    transit time
    C.
    flicker
    D.
    shot

  9. In communication systems, the modulating signal is also called

  10. A.
    base band signal
    B.
    side bands
    C.
    auxiliary signal
    D.
    none of the above

  11. Hue of a colour means

  12. A.
    amount of light energy received by eye
    B.
    predominant spectral purity of colour light
    C.
    amount of other colours present
    D.
    none of the above

  13. Consider the following statements: The radar pulse must be flat topped to

    1. allow accurate range measurement
    2. allow good minimum range
    3. prevent frequency changes in magnetron
    4. make the returned echoes easier to distinguish from noise.
    Which of the above are correct?

  14. A.
    1, 2, 3, 4
    B.
    1, 2, 3
    C.
    1, 2
    D.
    1, 3, 4

  15. Filter method and phasing method are the methods for generating

  16. A.
    SSB signal
    B.
    vestigial side band signal
    C.
    both SSB and vestigial sideband signals
    D.
    none of the above

  17. In amplitude modulation

  18. A.
    the amplitude of carrier varies in accordance with the amplitude of the modulating signal
    B.
    the modulating frequency lies in the audio range
    C.
    the amplitude of the carrier remains constant
    D.
    the amplitude of the carrier varies in accordance with the frequency of the modulating signal

  19. Which one the following is an advantage of AM over FM?

  20. A.
    FM has wide bandwidth
    B.
    FM has better
    C.
    FM is more immune to noise
    D.
    Probability of noise spike generation is less in AM