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ECE :: Communication Systems

  1. An FM signal is modulated by an 8 kHz sine wave and has maximum and minimum frequencies of 100.05 MHz and 99.95 MHz respectively. Its deviation frequency is

  2. A.
    100 kHz
    B.
    100 MHz
    C.
    500 kHz
    D.
    108 kHz

  3. Assertion (A): RF tuner is called front end of TV receiver

    Reason (R): RF tuner receives the TV signal and selects the required channel.

  4. A.
    Both A and R are correct and R is correct explanation of A
    B.
    Both A and R are correct but R is not correct explanation of A
    C.
    A is correct but R is wrong
    D.
    A is wrong but R is correct

  5. In TV broadcast, UHF range is

  6. A.
    606 - 790 MHz
    B.
    100 - 150 MHz
    C.
    41 - 68 MHz
    D.
    174 - 230 MHz

  7. The most commonly used microphone for public address systems is

  8. A.
    carbon
    B.
    crystal
    C.
    moving coil
    D.
    condenser

  9. Pre-emphasis and De-emphasis is done by using R-C circuit.

  10. A.
    True
    B.
    False

  11. Which of the following is Doppler effect not used?

  12. A.
    CW radar
    B.
    FM radar
    C.
    MTI system
    D.
    Moving target plotting on PPI

  13. If the AF voltage is raised to 10 V, while the AM is dropped to 200 Hz, what is the deviation?

  14. A.
    10 kHz
    B.
    15 kHz
    C.
    20 kHz
    D.
    40 kHz

  15. In pulse code modulation when the maximum frequency in the signal is fmax the bandwidth required will be

  16. A.
    p.fmax
    B.
    p.fmax
    C.
    ≤ (p.fmax)2
    D.
    ≥ (p.fmax)2

  17. The oscillator frequency is set for

  18. A.
    best picture
    B.
    max. sound
    C.
    min. sound
    D.
    sound in picture

  19. The main advantage of DM over PCM is

  20. A.
    less bandwidth
    B.
    less power
    C.
    simple circuit
    D.
    better S/N ratio