# Signals and Systems example problems?

1. Jul 16, 2007

### davegillmour

Are there any resources on the web that provide example problems (with solutions) to Signals problems? My textbook (shown below) lacks any clear example problems (shows answers without showing you how to get them). If someone could point me toward examples of Convolution, fourier series, or determining if a system is causal, time invariant ect would really help a lot.
Thanks

Text: https://www.amazon.com/Signals-Syst...0377231?ie=UTF8&s=books&qid=1184643299&sr=8-2

Last edited by a moderator: Apr 22, 2017
2. Jul 17, 2007

### Staff: Mentor

I googled convolution sample problems, and got lots of good hits. Here's the hit list:

Some of the hits are just from class descriptions, but others have full class notes and sample problems and exercises. You can probably just google fourier series sample problems, etc., to get the other hits you are looking for. Have fun!

3. Jul 22, 2007

### goldy

Causal and Non- causal system

hi there,
look i am gonna explain you Causal and Non-Causal systems..
A system is causal if response or output does not begin befor the input function is applied. This means that if input is applied at t=t', then for causal system, output will depend on values of input x(t) for t lessthan or equals to t'.
Mathematically,
y(t')=f[x(t),t<=t']
In other words, we can say that a causal system is non-anticipatory. The response or output of the causal system to an input does not depends upon future values of that input, but depends only on the present and the past values of the input.
A resistor is an example of continous time causal system because voltage accross it is given by the expression
v(t) = R.i(t)
and output v(t), i.e., voltage depends only on the input i(t) i.e., current at the present time...
All the real time systems are also causal systems since these system cannot know the future value of the input signal when it construct output signal.
Thus cuasal systems are physically realizable.

Few more examples for causal and non causal systems are as follows:

Causal Systems

1. y(t) = 0.2x(t) - x(t-1)
2. y(t) = 0.8x(t-1)
3. y(n) = x(n-1)

Non-causal systems

1. y(t) = x(t+1)
2. y(n-2) = x(n)
3. y(n) = x(n)-x(n+1)..
i think its too enough for now. I will also explain you about convolution, fourier, time varient and invarient system and whatever you want to know about signals and systems..

Last edited: Jul 22, 2007
4. Jul 23, 2007

### goldy

please try to study from "Oppenheim". This is a standard book for signals and systems