# Convolutions, Fourier Series...

#### eazhar

Joined Mar 16, 2007
2
Hi guys I just discovered this board and this will be my first post

The question on my homework reads:

Determine the Fourier Series representation of the signal x(t) = cos(2t+pi/4). If the impulse response of the system is h(t) = e^(-t)*u(t), what is the output y(t)?

I can find the fourier series representation of x(t) no problem. My question is, do you have to use that answer to evaluate the convolution, or are the two pretty much separate questions, using same signal?

#### DrNick

Joined Dec 13, 2006
110
just compute the convolution intigral, OR you can take the laplace transform of both, multiply and do the inverse transform (because convolution in time => multiplication in frequency). These are two seperate questions.

#### Dave

Joined Nov 17, 2003
6,969
OR you can take the laplace transform of both, multiply and do the inverse transform (because convolution in time => multiplication in frequency).
Agreed. This is the approach I would recommend you take.

Dave