Simple Signals for System Identification

Abstract

Event accessible for observation can be investigated by examining timeline of certain measureable values. Usually the process is referred to as time domain analysis of signals. Such a signal can be of many different origins. It could be comprised of values of electrical current or voltage, mechanical displacement or force, value of stock or popularity of politicians, reaction of the patient to medication, and essentially anything which is observable, measurable and quantifiable with reasonable accuracy. Observer will quite intuitively search for certain patterns and periods in signal if phenomena changes along the timeline. Some of them are easily detectable, such as periodic variation of the suns activity; some might appear as random fluctuations at the first glance, such as parameters of the seismic waves in Earth's crust. Of course sources of noise and other disturbances are usually omnipresent and will make matters much more difficult to observe and explain.