Biomedical Engineering Reference
In-Depth Information
Average power (3.8) satisfies the following conditions: [Note the limits; it is
bound.]
T
1
2
T
x
2
(
t
)
dt
0
<
Lim
T
<
∞
(3.8)
→∞
−
T
A classic definition given by McGillem and Cooper is as follows:
If the
power signal
has a non-zero value when the time
interval becomes infinite, then the signal has a finite average
power and is called a
Power Signal
. Then, an
energy signal
has zero average power, whereas a
power signal
has infinite
energy.
3.2 SIGNAL CHARACTERIZATION
(MEASURABLE PARAMETERS)
Thus far, we have simply provided discussions on signal representation. Let us turn to
specification of the signals and the “Characterization” of the signals by a few significantly
useful parameters, which include the following parameters:
1.
Signal energy
2.
Average power
3.
Bandwidth, or
4.
Time duration
5.
Time-bandwidth product
6.
Dimensionality of the signal
The first two, Energy and Power, were treated in the previous section. Thus, let us start
with the question, “What is the time duration of a signal?” The “Time Duration” of a
signal is defined in statistical terms as the normalized variance about its central moment
where the 1st moment is the mean or its center of gravity and the variance is generally the
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