Signals in real world?especially natural signals?

1. What are real world signals?
2. What is a natural signal?

What are real world signals?

Real-world signals will generally be bounded in energy, simply because there is no infinite source of energy available to us. Alternately, particularly when they characterize long-term phenomena (e.g. radiation from the sun), they will be bounded in power.

What is a natural signal?

Natural signals are the signals which are produced in the natural world. It is hard to create all of the natural signals artificially. Complete answer: The signal is a function that tells about the information of a particular phenomenon.