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ECE :: Signals and Systems

  1. A signal x(n) = sin(ω0n + φ) is the input to a linear time invariant system having a frequency response H(ejω) If the O/P of the system is Ax(n -n0), then the general form of H(e) will be

  2. A.
    - n0ω0 + β for any arbitrary real β
    B.
    - n0ω0 + 2pk for any arbitrary integer k
    C.
    n0ω0 + 2pk for any arbitrary integer k
    D.
    - n0ω0 + φ

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  3. Fourier transform of -jt f(t) is

  4. A.
    G'(f)
    B.
    2pG'(f)
    C.
    D.
    -jf F(f)

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  5. A casual system having the transfer function is excited with 10 ∪(t). The time at which the output reaches 99% of its steady-state value is

  6. A.
    2.7 sec
    B.
    2.5 sec
    C.
    2.3 sec
    D.
    2.1 sec

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  7. For exponential function e-at the Laplace transform 1/(s - a)

  8. A.
    True
    B.
    False

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  9. Consider the sequence x[n] = [- 4 - j5 1 + J2 4]

  10. A.
    [- 4 - J2.5 J2 4 - J2.5]
    B.
    [- J2.5 1 J2.5]
    C.
    [- J5 J2 0]
    D.
    [- x 1 4]

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  11. Assertion (A): The unit impulse function is also known as Dirac delta function.

    Reason (R): If a voltage

  12. 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 true, R is false
    D.
    A is false, R is true

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  13. DTFT (Discrete time Fourier transform) of x[n] = an∪[n] for -1 < a < + 1.

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  15. The z- transform of a systerm is If the ROC is |z| < 0.2, then the impluse response of the system is

  16. A.
    (0.2)n ∪[n]
    B.
    (0.2)n ∪[- n - 1]
    C.
    -(0.2)n ∪[n]
    D.
    -(0.2)n ∪[- n - 1]

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  17. ROC of sequence x[n] = (3)n ∪[n] + (4)n ∪[- n - 1]

  18. A.
    |z| > 4
    B.
    3 < |z| < 4
    C.
    |z| < 4
    D.
    |z| > 3

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  19. δ(t - b) is a pulse function.

  20. A.
    True
    B.
    False

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