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Simple question [Signals and Systems]

  1. May 30, 2007 #1
    Hi

    The following question is from Oppenheim/Wilsky/Nawab chapter 1.

    Consider a periodic signal

    [tex]x(t) = 1[/tex] for [tex]0 \leq t \leq 1[/tex]
    [tex]x(t) = -2 [/tex] for [tex]1 < t <2[/tex]

    with period [itex]T = 2[/itex]. The derivative of this signal is related to the impulse train

    [tex]g(t) = \sum_{k = -\infty}^{\infty}\delte(t-2k)[/tex]

    with period T = 2. It can be shown that

    [tex]\frac{dx(t)}{dt} = A_{1}g(t-t_{1}) + A_{2}g(t-t_{2})[/tex]

    Determine the values of [itex]A_{1}[/itex], [itex]t_{1}[/itex], [itex]A_{2}[/itex], and [itex]t_{2}[/itex].

    I got stuck with this one. Anyway here's my solution. Would appreciate any help in solving the problem.

    [tex]x(t) = \sum_{k = -\infty}^{\infty}(u(t-2k) - u(t-2k-1)) + (-2)(u(t-2k-1) - u(t-2k-2))[/tex]

    so

    [tex]x(t) = \sum_{k = -\infty}^{\infty}u(t-2k) - 3\sum_{k = -\infty}^{\infty}u(t-2k-1)) -2\sum_{k = -\infty}^{\infty}u(t-2k-2) [/tex]

    so

    [tex]\frac{dx}{dt} = g(t) - 3g(t-1) - g(t-2)[/tex]

    which is wrong...
     
  2. jcsd
  3. May 30, 2007 #2
    Okay I got it graphically, but what if I want to do it algebraically?
     
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