s-Domain Investigation

Note: This demonstration is best viewed on a computer. Certain features maybe unclear or not work on a mobile device.

Drag either of the points around the s-Domain graph to see what happens to the sinusoid in the Time-Domain graph.

1. What happens to the sinusoid when you drag the point horizontally?
2. What happens to the sinusoid when you drag the point vertically?
3. What happens to the sinusoid when the points sit on the y-axis?

4. Why are there a pair of points in the s-Domain that mirror each other in the x-axis?

Any sinusoid in the time-domain, whether it is decaying, growing or remains the same, is a real signal (it has no imaginary part). However, to represent this single real signal in the s-domain, we must use a pair of complex conjugate points in the s-domain. Untick the checkbox below to see what would happen to the sinusoid if the complex conjugate point was absent.

Tip: You might see the difference clearer when the point is on the right hand side of the graph. You can also drag the Time-Domain graph to rotate it for a clearer view.