Electrical Engineering ⇒ Topic : Energy and Power Signals

Energy and Power Signals

If a voltage v(t) is applied across a resistor R and produces a current i(t) through it, the instantaneous power per ohm is given by

                                                      ........... (1)

We can write the total energy (E) and average power (P) on a per ohm basis as follows:

                                              ............... (2)

                                          ................. (3)

The normalized energy content E of an arbitrary continuous-time signal x(t) is defined as

                                                                     .................... (4)

We can define the normalized average power P of x(t) as

                                                      .................... (5)

A signal x(t) is said to be an energy signal if 0 < E < ∞ and P = O. The signal x(t) is said to be power signal if 0 < P < ∞ and E = ∞. If the signal I x(t)I does not satisfy any of the above conditions, the signal is neither an energy signal nor a power signal.

All the short time or transient signals are energy signals, whereas power signals are cos ω_ot and sin ω_ot, etc.

The signals t^-1/2, (t² + a²)^-1/2 are neither energy nor power signals