A system with the impulse response h[n] = {3, 2, 2, −1} (n = 0…3) receives the step input x[n] = 5·u[n]. Find the output y[2].
Convolution & LTI systems worksheet with answers
1.Easy
h[n] = {3, 2, 2, −1}x[n] = 5·u[n]
y[2] =
2.Easy
The sequences x[n] = {2, −3, −2, 2} and h[n] = {2, −1, 4} both start at n = 0. Find the sample y[3] of the convolution y[n] = x[n] ∗ h[n].
x[n] = {2, −3, −2, 2}, n = 0…3h[n] = {2, −1, 4}, n = 0…2
y[3] =
3.Medium
The input x(t) = 2·e−3tu(t) is applied to a system with h(t) = e−2tu(t). Find the output y(1) at t = 1 s.
x(t) = 2·e−3tu(t)h(t) = e−2tu(t)t = 1 s
y(1) =
4.Medium
The pulse x(t) = 5 for 0 ≤ t < 0.5 s (zero elsewhere) is applied to a system with h(t) = e−4tu(t). Find the output y(2) at t = 2 s, after the pulse has ended.
x(t) = 5, 0 ≤ t < 0.5 sh(t) = e−4tu(t)t = 2 s
y(2) =
5.Hard
The input x(t) = 10·cos(60t) is applied to a system with h(t) = 2·e−20tu(t). Find the phase φ of the steady-state output relative to the input, in degrees.
h(t) = 2e−20tu(t)x(t) = 10cos(60t)
φ = °
6.Hard
A system obeys y′(t) + 0.5·y(t) = 10·x(t). Find its impulse response at t = 0.8 s, h(0.8).
y′ + 0.5y = 10xt = 0.8 s
h(0.8) =
Answer key
- 1. y[2] = 35
- 2. y[3] = −6
- 3. y(1) = 0.1711
- 4. y(2) = 0.002679
- 5. φ = −71.57 °
- 6. h(0.8) = 6.703
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