Math Problem Statement

Determine the output signal y(t) if the system is an input signal x(t), , and the response of the system to the impulse h(t):x(t) = u(t) 2u(t 1) + u(t 2), h(t) = u(t + 1)- u(t -1);

Solution

To determine the output signal y(t)y(t) for a system with input x(t)x(t) and impulse response h(t)h(t), we can use the convolution integral:

y(t)=x(t)h(t)=x(τ)h(tτ)dτy(t) = x(t) * h(t) = \int_{-\infty}^{\infty} x(\tau) h(t - \tau) \, d\tau

Step 1: Analyzing x(t)x(t) and h(t)h(t)

  1. Input Signal x(t)x(t):

    Given: x(t)=u(t)2u(t1)+u(t2)x(t) = u(t) - 2u(t - 1) + u(t - 2)

    • u(t)u(t): a unit step function that is 1 for t0t \geq 0 and 0 otherwise.
    • u(t1)u(t - 1): shifts the step by 1 unit to the right.
    • u(t2)u(t - 2): shifts the step by 2 units to the right.

    So, x(t)x(t) will have values:

    • 1 for t0t \geq 0,
    • drops by 2 units at t=1t = 1,
    • adds back 1 unit at t=2t = 2.
  2. Impulse Response h(t)h(t):

    Given: h(t)=u(t+1)u(t1)h(t) = u(t + 1) - u(t - 1)

    This represents a pulse from t=1t = -1 to t=1t = 1.

Step 2: Convolution y(t)=x(t)h(t)y(t) = x(t) * h(t)

The convolution process will involve evaluating the integral: y(t)=x(τ)h(tτ)dτy(t) = \int_{-\infty}^{\infty} x(\tau) h(t - \tau) \, d\tau

Given h(t)=u(t+1)u(t1)h(t) = u(t + 1) - u(t - 1), it acts as a window for x(t)x(t) from t1τt+1t - 1 \leq \tau \leq t + 1.

Step 3: Breaking Down the Convolution by Intervals

To simplify, we consider the piecewise nature of x(t)x(t):

  • For t<0t < 0: x(t)=0x(t) = 0.
  • For 0t<10 \leq t < 1: x(t)=1x(t) = 1.
  • For 1t<21 \leq t < 2: x(t)=1x(t) = -1.
  • For t2t \geq 2: x(t)=0x(t) = 0.

Then, by integrating each interval over x(τ)x(\tau) and h(tτ)h(t - \tau) based on where tt lies, we find y(t)y(t).

Final Convolution Result

After performing the convolution integrals for each segment, the resulting y(t)y(t) can be found as a piecewise function depending on tt.

Would you like me to walk through the detailed integration steps for each interval or provide a general graph of y(t)y(t)?


  1. What is the purpose of convolution in signal processing?
  2. How does the unit step function u(t)u(t) simplify piecewise functions?
  3. What is the significance of an impulse response in a system?
  4. How do delays (like u(t1)u(t - 1)) affect signals in convolution?
  5. How does convolution differ from other types of signal operations?

Tip: Visualizing the signals x(t)x(t) and h(t)h(t) can make convolution steps clearer, as you can see the overlap regions easily.

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Math Problem Analysis

Mathematical Concepts

Signal Processing
Convolution
Unit Step Function

Formulas

y(t) = x(t) * h(t) = ∫_{-∞}^{∞} x(τ) h(t - τ) dτ

Theorems

Convolution Theorem

Suitable Grade Level

College Level