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ECE :: Communication Systems

  1. In a TV, studio the function of vision switcher is to

  2. A.
    edit television programs
    B.
    relay television programs
    C.
    control zoom lens
    D.
    mix audio and video signals

  3. In the equation of M-ary PSK signal (where Ey is symbol energy), M becomes large. Then d will approach

  4. A.
    2
    B.
    infinity
    C.
    zero
    D.
    1

  5. The trapezoidal pattern of figure is obtained when examining an AM wave by an oscilloscope. Modulation factor of the wave is

  6. A.
    0.33
    B.
    0.5
    C.
    2
    D.
    1

  7. Y signal has maximum percentage of

  8. A.
    red colour
    B.
    blue colour
    C.
    green colour
    D.
    red and blue colours

  9. To ensure good transient response in audio systems the natural frequencies should be

  10. A.
    above 40 Hz and below 15 kHz
    B.
    above 40 Hz
    C.
    above 15 kHz
    D.
    below 40 Hz and above 15 kHz

  11. If k is dielectric constant of a medium, the velocity factor in that medium is

  12. A.
    3
    B.
    C.
    (k)1/3
    D.

  13. An AM signal and a narrowband FM signal with identical carriers, modulating signals and modulation index of 0.1 are added together. The resultant signal can be closely approximated by

  14. A.
    Broadband FM
    B.
    SSB with carrier
    C.
    DSB-SC
    D.
    SSB without carrier

  15. The equation v(t) = A cos [ωct + φ(t)] where A and ωc are constant and φ(t) is a function of base signal represents

    1. Phase modulation
    2. Amplitude modulation
    3. Angle modulation
    4. Frequency modulation
    Which of the above are true?

  16. A.
    3 only
    B.
    1, 3 and 4
    C.
    1, 2, 3, 4
    D.
    3 and 4 only

  17. An FM signal with deviation δ is passed through mixer. Its frequency is reduced five fold. The deviation in output of mixer is

  18. A.
    0.28
    B.
    δ
    C.
    5 δ
    D.
    very very high

  19. The total number of channels allotted for cellular telephone is

  20. A.
    666
    B.
    333
    C.
    221
    D.
    111