Introduction to digital signal processing The development is a result of advances in digital computer technology and integrated circuit fabrication. Computers and hardware of the past were large in size and were used in non-real time (off-line) computations and business applications. It is an area of science and engineering that has developed over past 30 years. Rapid development in IC technology starting with medium-scale integration and progressing to large scale integration and to VLS has spurred the development of powerful, smaller, faster and cheaper digital computers and hardware.
The development of technology has made it possible to construct highly sophisticated digital systems capable of performing complex digital signal processing functions and tasks. • These were too difficult and expensive for analog circuitry. • So many analog circuits of the past are being replaced by less expensive and more reliable digital hardware.
For many signals with extremely wide bandwidths, real time signal processing is a requirement. • For such signals, analog or optical signal processing is the only solution. • Where speed can be compromised digital circuit is preferable.
Digital processing hardware allows programmable operations. • Through programs one can easily modify signal processing functions. • Higher order of precision is achievable with digital hardware and software. • An explosive growth in DSP theory and applications has taken place.
analog signal processor analog input signal analog output signal Analog Signal Processing
Advantages of digital over analog signal processing • A digital programmable system allows flexibility in reconfiguring the signal processing operations by changing the program. • Reconfiguration of analog system needs a redesign of the hardware to be followed by testing and verification. • Tolerance of the analog circuit component make it difficult to control the accuracy of analog signal processing system. • Digital system provides much better control of accuracy. • Digital signals are easily stored in magnetic media (tape or disc) without deterioration or loss signal fidelity beyond that introduced in A/D conversion. • Digital signals become transportable and can be processed off-line in a remote library. • DSP system allows to implement a more sophisticated method in a digital computer. • Digital hardware is cheaper.
Limitations of DSP system • Speed of operation of A/D converters and digital signal processors are limited. • Analog systems with large bandwidths can not be processed with digital hardware.
digital signal processing system digital input signal digital output signal analog output signal analog input signal Digital signal processor D/A Converter A/D Converter Block diagram of a digital signal processing system
Classification of signals A signal is described by a function of one or more independent variable. The following signal is a real-valued signal. A complex valued signal is