thecritic said:
Why do we call this the Frequency Domain response?
What does 's' represents?
The Laplace Transform gives you the Transient Frequency Response while
The Fourier Transform gives the Steady State [long term] Frequency Response
This is in contrast to the Time Domain Response which is what you see on an oscilliscope.
s is complex frequency
s = k + jw k the real part of the complex pole/zero and w the imaginary part
If you disturb a harmonic oscillator, it will oscillate and slowly die down until it stops.
Same is true for any system responding to an input.
Unless overdamped, you will see a sinusoidal oscillation dying down exponentially.
If you hit any system with a step function input [ abrupt change to a new value ]
it will go to the new commanded value but it will oscillate about that value before
settling down. Think of your car suspension system going over a bump.
If k is very small, the transient oscillation response takes a long time; if very large, response is over quickly.
If w is very small, the oscillation frequency is low; if very large, the frequency is very large.