This document defines and provides examples of various types of signals and systems. It discusses continuous and discrete time signals, even and odd signals, deterministic and random signals, periodic and aperiodic signals. It also defines linear and nonlinear systems, time invariant systems, causal and non-causal systems, memory and memoryless systems, and stable and unstable systems. Examples are provided for each type of signal and system defined.

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 Sohail Ahmad 2016-Uet-Qet.Swl-Elect-08
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4. The signals are detectable physical
quantities that vary with time, space
or any other independent variable or
variables.
 For Example:
Sine Wave

5.  Signals can be classified as:
 Continuous time Signals
 Discrete time Signals

6.  If the independent variable (t) is
continuous, then the corresponding
signal is continuous time signal.
 For Example:

7.  If the independent variable (t) takes
on only discrete values.
 For Example:

8.  Even and Odd Signals
 Energy and Power Signals
 Deterministic and Random Signal
 Periodic and APeriodic Signals

9.  If by changing independent axis, without changing
dependent axis the magnitude of the signal remains
same, the signal is termed as even signal.
 For Example: Cosine Signal
f (t) = f (-t)
f(x)= x^2
All Square roots is Even Signal

10.  When independent variable is
changed and there is significant
change in the amplitude of function,
it is called odd signal.
 For Example: Sine Signal.
f (t) =- f (-t)
f(x) = x

11.  Any signal squared and integrated
over time where it exists is energy
signal. Theses signals contain finite
amount of energy and zero power.
 Time average of energy signal is
Power signal, they contain infinite
energy.

12.  A random signal cannot be
described by any mathematical
function.
 For Example:

13.  Deterministic Signal is one that can be described
mathematically.
 For Example:

14.  Any continuous-time signal that
satisfies the condition: x(t+T) is a
periodic Signal. m1T1=m2T2 = Tₒ =
Fundamental period
 For Example: cos(tp/3)+sin(tp/4)
 T1=(2p)/(p/3)=6; T2 =(2p)/(p/4)=8;
 T1/T2=6/8 = (rational number) = m2/m1
 m1T1=m2T2 >Find m1 and m2
 6.4 = 3.8 = 24 = Tₒ

15.  APeriodic Signals is not satisfy Equation.
 For Example:
x(t) = u(t) - ½
x(t) = 4u(t) + 2sin(3t)
x(t) = cos(4t) + 2sin(8t)
x(t) = 3cos(4t) + sin(pt)
x(t) = cos(3pt) + 2cos(4pt)

16. A set of principles or procedures
according to which something is
done. An organized scheme or
method.
 For Example:
Robot Arm and Remote TV

17. Systems can be classified as:
 Linear and Non linear Systems
 Time Invariant Systems
 Causal and Non- Causal Systems
 Memory and Memory less Systems
 Stable and Unstable Systems

18. A system which depends upon past
and future values is called a
Memory System.
For Example:
y(t) = 3x(t) + 4x(t+6)
y(t) = 2x(t) + x(t-4)
y(t) = 4x(t) + 3x(t+6)

19. A system is said to be memory less, if
their present value of the output
depends only on the present value of
the input.
For Example:
y(t) = x(t)
Y(t) = 3x(t)

20. System which outputs are dependent on present
and past input, system is called causal system.
For Example:
y(t) = 3x(t) + x(t-2)
y(t) = 5x(t) + 3x(t+5)
y(t) = 3x(t)

21. Non causal systems are those systems,
the output of which depends on future
inputs.
For Example:
y(t) = 5x(t) + 3x(t+5)
y(t) = 2x(t) + 3x(t-
4)+4x(t+6)
y(t) = 4x(t+3)

22. The End