This new resource introduces the concepts, equations, and terminology of Digital Signal Processing, and also provides the tools needed to analyze and design digital filters. With emphasis on digital filtering, this book applies the reader's knowledge of AC circuits, trigonometry, algebra, calculus and analog filter design to digital signal processing. This book also assists users in the understanding and use of available digital filtering software to meet design criteria. (Keywords: Digital Electronics)
Digital signal processing (DSP) refers to anything that can be done to a signal using code on a computer or DSP chip. To reduce certain sinusoidal frequency components in a signal in amplitude, digital filtering is done. One may want to obtain the integral of a signal. If the signal comes from a tachometer, the integral gives the position. If the signal is noisy, then filtering the signal to reduce the amplitudes of the noise frequencies improves signal quality. For example, noise may occur from wind or rain at an outdoor music presentation. F iltering out sinusoidal components of the signal that occur at frequencies that cannot be produced by the music itself results in recording the music with little wind and rain noise. Sometimes the signal is corrupted not by noise, but by other signal frequencies that are of no present interest. If the signal is an electronic measurement of a brain wave obtained by using probes applied externally to the head, other electronic signals are picked up by the probes, but the physician may be interested only in signals occurring at a particular frequency. By using digital filtering, the signals of interest only can be presented to the physician.
Originally signal processing was done only on analog or continuous time signals using analog signal processing (ASP). Until the late 1950s digital computers were not commercially available. When they did become commercially available they were large and expensive, and they were used to simulate the performance of analog signal processing to judge its effectiveness. These simulations, however, led to digital processor code that simulated or performed nearly the same task on samples of the signals that the analog systems did on the signal. After a while it was realized that the simulation coding of the analog system was actually a DSP system that worked on samples of the input and output at discrete time intervals.