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ECE :: Signals and Systems

  1. If F(jω) is the Fourier transform of f(t) then f(t) =


  2. The Laplace transform of sin ωt is

  3. A.
    B.
    C.
    D.
    none of the above

  4. If f(t) is an even function

  5. A.
    True
    B.
    False

  6. If average correlation between v1(t) and v2(t) is R12(t) and average correlation between v2(t) and v1(t) is R21(t) then

  7. A.
    R12(t) = R21(t)
    B.
    R21(t) = R12(t)
    C.
    R12(t) = - R21(t)
    D.
    none of these

  8. A stationary process has

  9. A.
    all statistical properties independent of time
    B.
    all statistical properties dependent of time
    C.
    zero variance
    D.
    ensemble average equal to time average

  10. Algebraic expression for z-transform of x[n] is X[z]... What is the algebraic expression of z-transform of ejω0n x[n]?

  11. A.
    X(Z - Z0)
    B.
    X(e-jW0z)
    C.
    X(ejω0z)
    D.
    X(Z)jω0z

  12. The waveform shown in the given Figure can be written as

  13. A.
    v(t) = u(t - 1) + u(t - 2) + u(t - 3) + u(t -4)
    B.
    v(t) = u(t - 1) + u(t - 2) + u(t - 3) + u(t -4) - u(t - 5)
    C.
    v(t) = u(t - 1) + u(t - 2) + u(t - 3) + u(t -4) - 4u(t - 5)
    D.
    v(t) = u(t - 1) + u(t - 2) + u(t - 3) + u(t -4) + 4u(t - 5)

  14. Assertion (A): The function δ'(t - b) is equal to 0 for tb

    Reason (R): A number of impulses spaced from one another form an impulse train.

  15. 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

  16. The range of values of a and b for which the linear time invariant system with impulse response.
    h(n) = an n ≥ 0
            = bn n < 0
    will be stable if

  17. A.
    |a| > 1, |b| > 1
    B.
    |a| < 1, |b| < 1
    C.
    |a| < 1, |b| > 1
    D.
    |a| > 1, |b| < 1

  18. If f(- t) = f(t), the function f(t) has only cosine terms.

  19. A.
    True
    B.
    False