Hint: start with substitution: u=t-λ
a) Consider the function
Show that the convolution of h(t) with a function f(t) is simply the average of f(t) over the previous T seconds (i.e., if y(t)=h(t)*f(t) then y(t) is the average of f(t) for the previous T seconds).
b) Now consider the function
If y(t)=h(t)*f(t) use words to describe the relationship between y(t) and f(t).
Here is a related problem to think about if the answer is not coming to you: If I give you the high temperature of every day for the last month and ask you to predict the high temperature tomorrow there are several ways you could do it. One simple way is to average the temperatures over some time period (e.g., one week) and use that as the prediction. How could you modify the average to get a better prediction (i.e., without looking at trends (slopes) in the data, but only aggregates (integrals/averages...) of the data)?
Note that for both part a and part b.
Given a system with impulse response
Use the convolution integral to find the zero state solution if f(t)=tγ(t) (i.e.. f(t)=t for t≥0). Note: this is a problem you could not have done in E11. Note also that the integration is somewhat long and tedious but not particularly difficult if you recall (i.e., look it up in an integral table) that
A system defined by the differential equation
has the impulse response
a) If the input is a ramp (f(t)=2.5·tγ(t)), and the initial conditions are , find the output without solving any additional differential equations by using the results of previous problem.
b) What is the output if the input is f(t)=-2γ(t), and the initial conditions are ? Do as little additional work as possible.
The circuit shown
with C=0.25F, L=1H, R=5Ω and f(t)=ein(t), and y(t)=eout(t) is defined by the differential equation
and has the impulse response
The input to the system is f(t)=3γ(t), and the initial conditions are
a) Using the impulse response and the convolution integral, find an expression for the zero state response
b) Find an expression for the zero input response
c) Find the complete response
d) Use MATLAB to plot the zero state, zero input and complete response on one set of axes. Include a legend to differentiate between them. Turn in the plot and the MATLAB code.
The image below shows two functions, x(t) and yIt), as well as the convolution, z(t)=x(t)*y(t). The function x(t) is a rectangular pulse with height A and width a. The function y(t) is a rectangular pulse with height B and width b. Assume A>B and b>a, as shown.
Determine the values of C, d, e, and f in terms of A, B, a and b.