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ECE :: Communication Systems

  1. If ω is the frequency of modulating voltage in FM, the modulation index is proportional to

  2. A.
    ω
    B.
    1/ω
    C.
    ω
    D.
    1/ω

  3. Which camera tube has gamma of almost unity?

  4. A.
    Vidicon
    B.
    Plumbicon
    C.
    New vicon
    D.
    Saticon

  5. The baud rate is

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

  7. In a tape recorder

  8. A.
    the width of air gaps of record and erase heads is almost equal
    B.
    the air gap of record head is wider than the air gap of erase head
    C.
    the air gap of erase head is wider than the air gap of record head
    D.
    any of the two air gaps can be wider than the other

  9. When satellite radio beam is aimed towards earth, it illuminates on the earth for an oval shaped area called

  10. A.
    foot print
    B.
    beam area
    C.
    satellite service area
    D.
    radiated area

  11. Which of the following is invariably found in SSB?

  12. A.
    Tuned modulator
    B.
    Class B, RF amplifier
    C.
    Class C, audio amplifier
    D.
    All of the above

  13. In the spectrum of a frequency modulated wave

  14. A.
    carrier frequency cannot disappear
    B.
    carrier frequency vanishes when modulation index is large
    C.
    the number of significant sidebands depends upon modulation index
    D.
    none of the above

  15. Which of the following pulse communication system is inherently immune to noise?

  16. A.
    PPM
    B.
    PCM
    C.
    PWM
    D.
    PAM

  17. In a PCM system, if we increase the quantization levels from 2 to 8, how do the relative bandwidth requirements vary?

  18. A.
    Get doubled
    B.
    Get tripled
    C.
    Remains same
    D.
    Become eight times

  19. If the target area is small compared to wavelength of radar the situation is called

  20. A.
    resonance region
    B.
    Rayleigh region
    C.
    optical region
    D.
    binomial region