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ECE :: Communication Systems

Communication Systems - Section 1
Communication Systems - Section 2
Communication Systems - Section 3
Communication Systems - Section 4
Communication Systems - Section 5
Communication Systems - Section 6
Communication Systems - Section 7
Communication Systems - Section 8
Communication Systems - Section 9
Communication Systems - Section 10
Communication Systems - Section 11
Communication Systems - Section 12
Communication Systems - Section 13
Communication Systems - Section 14
Communication Systems - Section 15
Communication Systems - Section 16
Communication Systems - Section 17
Communication Systems - Section 18
Communication Systems - Section 19
Communication Systems - Section 20
Communication Systems - Section 21
Communication Systems - Section 22
Communication Systems - Section 23
Communication Systems - Section 24
Communication Systems - Section 25
Communication Systems - section-26
Communication Systems - Section-27

  1. A 400 W carrier is amplitude modulated with m = 0.75. The total power in AM is

    2. A.
    400 W
    B.
    512 W
    C.
    588 W
    D.
    650 W

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  2. c(t) and m(t) are used to generate an FM signal. If the peak frequency deviation of the generated FM signal is three times the transmission bandwidth of the AM signal, then the coefficient of the term cos [2p(1008 x 103t)] in the FM signal (in terms of the Bessel Coefficients) is

    3. A.
    5 J4(3)
    B.
    J8(3)
    C.
    J8(4)
    D.
    5 J4(6)

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  3. Non-coherently detection is not possible for

    4. A.
    PSK
    B.
    ASK
    C.
    FSK
    D.
    both (a) and (c)

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  4. Tracking of extra terrestrial objects requires

    5. A.
    high transmitting power
    B.
    very sensitive receiver
    C.
    fully steerable antenna
    D.
    all of the above

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  5. Assertion (A): Free space does not interfere with normal radiation and propagation of radio waves

    Reason (R): Free space has no magnetic or gravitational fields.

    6. 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

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  6. In radar systems PRF stands for

    7. A.
    Power Return Factor
    B.
    Pulse Return Factor
    C.
    Pulse Repetition Frequency
    D.
    Pulse Response Factor

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  7. Which of the following cannot be the Fourier series expansion of a periodic signal?

    8. A.
    x(t) = 2 cos t + 3 cos 3t
    B.
    x(t) = 2 cos pt + 7 cos t
    C.
    x(t) = cos t + 0.5
    D.
    x(t) = 2 cos 1.5pt + sin 3.5 pt

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  8. Which of the following is the indirect way of FM generation?

    9. A.
    Reactance bipolar transistor modulator
    B.
    Armstrong modulator
    C.
    Varactor diode modulator
    D.
    Reactance FM modulator

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  9. A telephone exchange has 9000 subscribers. If the number of calls originating at peak time is 10, 000 in one hour, the calling rate is

    10. A.
    0.9
    B.
    10/9
    C.
    0.81
    D.
    0.1

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  10. If C is capacity of noisy channel, (bits/s), δf is bandwidth Hz and S/N is signal to noise ratio, then

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