1. ELEC 423 Digital Signal Processing Prof. Siripong Potisuk

2. What is a function? A rule of correspondence that maps or assigns to each element (x) of a given set A a uniquely determined element (y) of another set B f: A  B (f maps A into B) Domain of f = set of all x Range of f = set of all y

3. The Usual Notation y = f(x) A single x cannot be mapped or assigned to more than one y Multiple x’s can be assigned to a single y Element of Domain = independent variable(s) Element of Range = dependent variable

4. Signal A function of independent variables such as time, distance, position, etc. One-dimensional signal : speech, audio, music, ECG, seismic, time series Two-dimensional signal : image Three-dimensional signal : video

9. Signal Processing Extract useful information carried by the signal Concerned with the mathematical representation of the signal and the algorithmic operation carried out on it to extract the information present

10. Typical Signal Processing Operations Addition/multiplication Amplification/attenuation Integration/differentiation Delay/advance Modulation/demodulation Multiplexing/demultiplexing filtering

11. Typical Signal Processing Applications Audio Processing (noise reduction, equalization, special effects) Communications system Echo cancellation in telephone networks Speech Processing (recognition, synthesis, compression, enhancement) Image Processing ( compression, recognition) Biomedical signal processing

12. Why Digital Signal Processing? Operation of digital circuits not dependent on precise values of the digital signals Require only bistable circuits and storage medium to process, store, and transmit signals Possibility of perfect signal regeneration Low cost of digital processor hardware

13. Benefits (continued) Any desirable accuracy achievable by increasing the binary wordlength subject to cost limitation The same digital computer technology used for general information processing can be used for DSP Applicability to very low frequency signals (seismic applications)

14. Disadvantages Increased system complexity (A/D and D/A) Limited range of frequencies available for processing because of the sampling requirement Digital systems mostly constructed using active devices that consume electrical power Advantages far outweigh disadvantages

15. Block Diagram of a Communication System