Overview of Signals & Systems Hany Ferdinando Dept. of Electrical Engineering Petra Christian University

Overview of Signals and Systems - Hany Ferdinando2 General Overview It is an general introduction to signals and systems Examples of signals and systems Applications of signal and system theory

Overview of Signals and Systems - Hany Ferdinando3 Introduction 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  Communication, aeronautics, circuit design, acoustics, seismology, biomedical, energy generation and distribution, chemical process control, speech processing, etc.

Overview of Signals and Systems - Hany Ferdinando4 Communication Design of RF transceiver Modulation Choosing the suitable media for transmission Noise removal Echo cancellation Filtering

Overview of Signals and Systems - Hany Ferdinando5 Circuit Design Block diagram concept Simulation and analysis  Transient and steady state response Transformation Filter design Sampling

Overview of Signals and Systems - Hany Ferdinando6 Biomedical Engineering Signal processing of EEG and ECG Image processing in USG Noise removal Signal amplification Filtering

Overview of Signals and Systems - Hany Ferdinando7 Energy Generation & Distribution Active power filter High freq. in the power line signal Simulation and analysis Block diagram concept

Overview of Signals and Systems - Hany Ferdinando8 Speech Processsing Noise removal Filtering Transformation

Overview of Signals and Systems - Hany Ferdinando9 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,

Overview of Signals and Systems - Hany Ferdinando10 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.)

Overview of Signals and Systems - Hany Ferdinando11 General Concept 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 System outputinput

Overview of Signals and Systems - Hany Ferdinando12 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

Overview of Signals and Systems - Hany Ferdinando13 General Concept (cont.) 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  Discrete-time signals  Continuous-time signals

Overview of Signals and Systems - Hany Ferdinando14 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

Overview of Signals and Systems - Hany Ferdinando15 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

Overview of Signals and Systems - Hany Ferdinando16 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

Overview of Signals and Systems - Hany Ferdinando17 General Concept (cont.) There are two systems:  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

Overview of Signals and Systems - Hany Ferdinando18 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

Overview of Signals and Systems - Hany Ferdinando19 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. Filter + + signal s noise n received signal u = s + n filtered signal y

Overview of Signals and Systems - Hany Ferdinando20 App. to Communication Eng. Communication engineering deals with transferring information from one location to another. It uses high frequency waves as carrier. Modulator message s Modulated carrier (z) Demodulator message y Modulated carrier (z)

Overview of Signals and Systems - Hany Ferdinando21 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 Cruise Controller Car Car speed (v) Ref. speed (vr)

Overview of Signals and Systems - Hany Ferdinando22 App. to Power System Power Filter Voltage and current with high frequency due to non linear load Controller Normal signal

Overview of Signals and Systems - Hany Ferdinando23 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