Overview of Signals & Systems

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

2. 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 Ferdinando

3. 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 Ferdinando

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

5. Circuit Design • Block diagram concept • Simulation and analysis • Transient and steady state response • Transformation • Filter design • Sampling Overview of Signals and Systems - Hany Ferdinando

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

7. 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 Ferdinando

8. Speech Processsing • Noise removal • Filtering • Transformation Overview of Signals and Systems - Hany Ferdinando

9. 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 Ferdinando

10. 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 Ferdinando

11. input System output 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 Overview of Signals and Systems - Hany Ferdinando

12. 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 Ferdinando

13. 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 Ferdinando

14. 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 Ferdinando

15. 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 Ferdinando

16. 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 Ferdinando

17. 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 Ferdinando

18. 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 Ferdinando

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

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

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

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

23. 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 Overview of Signals and Systems - Hany Ferdinando