The size of a signal indicates the largeness or strength of a signal. Such a measurement must consider not only the signal magnitude, but also signal duration.
Signal size can be measured in two ways: energy and power. Energy is used to measure aperiodic signals, while power is used for periodic signals.
Signal Energy
If we just integrate a signal
Comment
The signal energy as described above does not indicate the actual energy (in the conventional sense) of the signal because the signal energy depends not only on the signal, but also on the load
Signal Power
Signal energy must be finite for it to be a meaningful measure of signal size, and a necessary condition for signal energy to be finite is that
However, another type of signals we are interested in are periodic functions such as
RMS Value
The square root of
Examples
Example 1
This signal amplitude
Example 2
This signal amplitude does not
Reference
- Linear Systems and Signals, 1.1