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Showing posts from September 7, 2010

Filters

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1.1     Introduction The function of a filter is to remove unwanted parts of the signal (such as random noise) or to extract useful parts of the signal (such as the components lying within a certain frequency range). There are two main kinds of filter: analog and digital. They are quite different in their physical makeup and in how they work. An analog filter uses analog electronic circuits made up from components such as resistors, capacitors and op-amps to produce the required filtering effect, whereas a digital filter uses a digital processor to perform numerical calculations on sampled values of the signal. The processor may be a general-purpose computer such as a PC, or a specialized DSP (Digital Signal Processor) chip. Microwave filters represent a class of electronic filter, designed to operate on signals in the megahertz to gigahertz frequency ranges (medium frequency to extremely high frequency). This frequency range is the range used by most broadcast radio, television, wire