Transcript Overview of Signals & Systems

Overview of Signals & Systems
Hany Ferdinando
Dept. of Electrical Engineering
Petra Christian University
General Overview
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It is an general introduction to signals
and systems
Examples of signals and systems
Applications of signal and system
theory
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Introduction
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The concept of signals and systems arise in
and extremely wide variety of fields
They have important role in such diverse
areas of science and technology
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Communication, aeronautics, circuit design,
acoustics, seismology, biomedical, energy
generation and distribution, chemical process
control, speech processing, etc.
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Communication
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Design of RF transceiver
Modulation
Choosing the suitable media for
transmission
Noise removal
Echo cancellation
Filtering
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Circuit Design
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Block diagram concept
Simulation and analysis
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Transient and steady state response
Transformation
Filter design
Sampling
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Biomedical Engineering
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Signal processing of EEG and ECG
Image processing in USG
Noise removal
Signal amplification
Filtering
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Energy Generation & Distribution
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Active power filter
High freq. in the power line signal
Simulation and analysis
Block diagram concept
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Speech Processsing
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Noise removal
Filtering
Transformation
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Definition
A signal is a phenomenon, arising in some
environment, that may be describe quantitatively
Examples of signal are
 voltages and current in electrical circuit,
 audio signals, visual signals,
 sequence of bits from computers,
 RF signal from transmitter,
 ECG and EEG signal,
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Definition
A system is any part of environment that causes
certain signals that exist in that environment to be
related
Examples of system are
 an electrical circuit (it relates voltage and current),
 a television (audio and visual signals),
 a country (national income, demography, etc.)
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General Concept
input
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System
output
System usually has input and output
Such a system is called input-output
system
We do not require that the input
determine the output uniquely
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Examples…
Resistive electrical circuit system
Consider a resistor element connected to a
voltage source. We can assume that voltage is
the input and current acts as output. But for
some input voltage, there is no unique output
current
This is input-output system
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General Concept (cont.)
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If an input uniquely determines the
output, it is called input-output
mapping system
Usually, signal is a function of time,
such a signal is called time-signals
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Discrete-time signals
Continuous-time signals
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Examples…
Parity Bit Generator
A Parity bit generator always receives the
digital input and gives the output uniquely for
every input. It depends on the parity bit
generator uses even- or odd-parity
This is input-output mapping system
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Examples…
Dow-Jones averages
It is a weighted average of the price of a
selected portfolio of stocks traded in NYSE,
which has been daily computed and recorded
since 1897
This is discrete-time signals
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Examples…
The outdoor temperature
The outdoor temperature at any given place
taken as a continuous function of time. The
physical world abounds with continuous-time
signals
This is continuous-time signals
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General Concept (cont.)
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There are two systems:
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Discrete-time systems (systems
associated with discrete-time signals) 
the time axis is finite and countable
Continuous-time systems (system
associated with continuous-time signals)
 the time axis is infinite and
uncountable
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App. to Signal Processing
A typical problem in the area of signal processing
is the removal of unwanted noise from a signal.
Can you give examples?
A model u = s + n is frequently used, where s is
transmitted signal and n is noise added to the
signal
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App. to Signal Processing
The problem is how to design a filter as shown in
figure below, whose function is to remove or at
least attenuate the noise.
noise
n
signal
s
+
+
received signal
u=s+n
Filter
Overview of Signals and Systems - Hany Ferdinando
filtered signal
y
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App. to Communication Eng.
Communication engineering deals with
transferring information from one location to
another. It uses high frequency waves as carrier.
Modulated
carrier (z)
message
s
Modulated
carrier (z)
Modulator
Demodulator
Overview of Signals and Systems - Hany Ferdinando
message
y
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App. to Automatic Control
Control engineering concerns itself with the
design of automatic controller, whose purpose is
to govern the dynamic behavior of a given
system, e.g. automatic cruise control in a car
Ref. speed (vr)
Cruise
Controller
Car speed (v)
Car
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App. to Power System
Voltage and current with high
frequency due to non linear load
Power
Filter
Normal signal
Controller
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Next…
We have discussed the overview of signals and
systems. This is important in giving a brief information
about signal and system.
Next, we will study an introduction to signal. You can
read books:
Signals and Systems by Alan V. Oppenheim, chapter 2,
page 7-35
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