Smoothing Data with Average Calculation

[rjunior]

How to make it causal:

y (n) = x ((n-1) + x(n) + x(n+1))/3

 

[Jaynte]

you need to move the transfer function such that it is located in the right half plane, n>=0

replace n=m-1, this will move the function in time

y(m)=x((m-2)+x(m-1)+x(m))/3

 

[tedbradly]

you need to move the transfer function such that it is located in the right half plane, n>=0

replace n=m-1, this will move the function in time

y(m)=x((m-2)+x(m-1)+x(m))/3

So why does y magically become indexed at m instead of m - 1?

It also seems like you can never know if that system is causal (though you can know it is non-causal) without knowing what x(n) looks like since he is evaluating x at x(n-1) + x(n) + x(n+1).

 

[Jaynte]

Sorry for the index.

If the system is Linear Time Invariant it is casual if h(n)=0 for t<0