Determining the causality of a signal with it's pole-zero plot

1. How do you find the causality of a pole-zero plot?
2. How do you know if a signal is causal?
3. Why do we plot poles and zeros?

How do you find the causality of a pole-zero plot?

If the ROC extends outward from the pole with the largest (but not infinite) magnitude, then the system has a right-sided impulse response. If the ROC extends outward from the pole with the largest magnitude and there is no pole at infinity, then the system is causal.

How do you know if a signal is causal?

A system is said to be causal if it does not respond before the input is applied. In other words, in a causal system, the output at any time depends only on the values of the input signal up to and including that time and does not depend on the future values of the input.

Why do we plot poles and zeros?

Pole-Zero plot is an important tool, which helps us to relate the Frequency domain and Z-domain representation of a system. Understanding this relation will help in interpreting results in either domain. It also helps in determining stability of a system, given its transfer function H(z).