Discrete systems in series
We have two discrete systems, and their impulse responses are h1(n) and h2(n). Then when these discrete systems are connected in series, then overall impulse response:
Where:
As you noticed there were changing made:
This is nothing more than convolution of impulse responses of both discrete systems:
Discrete systems in parallel
If we have two discrete systems connected in parallel:
As we see, there is a simple sum of output queues of each discrete system. So we can assume, that the overall impulse response is the sum of systems connected in parallel:
