Chapter 1
Textbook: Chapter 1, subchapter1.1
1.1Graphical representations
of continuous time and
discrete time signals
1.1.2 Signal energy and power
• Total energy over the time interval 𝑡1 ≤ 𝑡 ≤ 𝑡2 in
a continuous-time signal x(t) is
• The time-averaged power is obtained by dividing
eq. (1.4) by the length, 𝑡1 − 𝑡2 , of the time
interval
• Total energy in a discrete-time signal x[n]
over the time interval 𝑛1 ≤ 𝑛 ≤ 𝑛2
• dividing by the number of points in the
interval, 𝑛1 − 𝑛2 + 1 , yields the average power
3 classes of signal based on
power and energy
1. class of signals with finite total energy,
i.e., those signals for which 𝐸∞ < ∞, then
𝑃∞ = 0
2. Class of signals with finite average power,
𝑃∞ > 0, then 𝐸∞ = ∞
3. Neither 𝐸∞ nor 𝑃∞ are finite
3 classes of signal based on
power and energy  for
continuous signal
𝑬∞ < ∞
1.2 Transformation of the
independent variable
(continuous time signal)
1.2 Transformation of the
independent variable (discrete
time signal)