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Discussion :: Exam Questions Paper

  1. Consider the signal x(n) = 1 + sinn + 3 cosn + cos . Then Fourier series coefficients are __________ .

  2. A.
    1, - j, + j, j, - j
    B.
    1, + j, - j, - j , + j
    C.
    1, 3 - j, 3 + j, j, - j
    D.
    1, 3 + j, 3 - j, - j, + j

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    Answer : Option A

    Explanation :

    The signal x(n) = 1 + sinn 3 cos n + cos n + cos

    is periodic with period N, and we can expand x[n] directly in terms of complex exponentials to obtain

    Collecting terms, we find that

    Thus for Fourier series coefficients for this example are

    a0 = 1,

    a1 = + = -j,

    a-1 = - = +j,

    a2 = j,

    a-2 = -j.


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