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ECE :: Signals and Systems

  1. For the signum function sgn(t), F(jω) =

  2. A.
    B.
    C.
    jω
    D.
    2 j

  3. In the periodic train of rectangular pulses F0 = (V0/T)d

  4. A.
    True
    B.
    False

  5. Z transform of [(Xk±k0)] =

  6. A.
    z±k0 X(z)
    B.
    z±k0 X(z)
    C.
    D.
    none of the above

  7. If a sequence is causal then ROC is (where a is any number)

  8. A.
    |z| > a
    B.
    |z| < a
    C.
    |z| = a
    D.
    Entire Plane

  9. If f(t) ↔ F(jω), and f(t) is real, then


  10. X and Y are two random variable and Z = X + Y. Let σx2, σy2 and σz2 be variance of X, Y and Z. Then

  11. A.
    σz2 = σx2 + σy2
    B.
    σz2 ≤ σx2 + σy2
    C.
    σz2 < σx2 + σy2
    D.
    σz2 > σx2 + σy2

  12. Consider the following sets of values of E, R and C for the circuit in the given figure.

    1. 2 V, 1 Ω, 1.25 F
    2. 1.6 V, 0.8 Ω, 1 F
    3. 1.6 V, 1 Ω, 0.8 F
    4. 2 V, 1.25 Ω, 1 F
    Which of these of values will ensure that the state equation is valid?

  13. A.
    1 and 4
    B.
    1 and 2
    C.
    3 and 4
    D.
    2 and 3

  14. Assertion (A): The conditions under which it is possible to write Fourier series of a periodic function are called Drichlet conditions.

    Reason (R): If f(t) = - f(- t), it is refereed to as odd symmetry.

  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. Initial value theroem for sequence x[n] is

  17. A.
    B.
    C.
    a and b
    D.
    X(z)at z = 0

  18. L[c1f1(t) + c2f2(t)] =

  19. A.
    c1 F1 (jω) + c2 F2(jω)
    B.
    c1 F1 (jω) - c2 F2(jω)
    C.
    c1 F1 (jω) + c2 F2(jω) + c1c2
    D.
    c1 F1 (jω) + c2 F2(jω) + c1/c2