Causal and Non- causal system
hi there,
look i am going to 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 continuous time causal system because voltage across 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..