數(shù)字濾波器簡介外文翻譯-wenkub
2023-05-19 01:46:52 本頁面
【正文】 l makeup and in how they work. An analog filter uses analog electronic circuits made up from ponents such as resistors, capacitors and opamps to produce the required filtering effect. Such filter circuits are widely used in such applications as noisereduction, video signal enhancement, graphic equalisers in hifi systems, and many other areas. There are wellestablished standard techniques for designing an analog filter circuit for a given requirement. At all stages, the signal being filtered is an electrical voltage or current which is the direct analogue of the physical quantity (. a sound or video signal or transducer output) involved. A digital filter uses a digital processor to perform numerical calculations on sampled values of the signal. The processor may be a generalpurpose puter such as a PC, or a specialised DSP (Digital Signal Processor) chip. The analog input signal must first be sampled and digitised using an ADC (analog to digital converter). The resulting binary numbers, representing successive sampled values of the input signal, are transferred to the processor, which carries out numerical calculations on them. These calculations typically involve multiplying the input values by constants and adding the products together. If necessary, the results of these calculations,which now represent sampled values of the filtered signal, are output through a DAC (digital to analog converter) to convert the signal back to analog form. Note that in a digital filter, the signal is represented by a sequence of numbers, rather than a voltage or current. The following diagram shows the basic setup of such a system. Advantages of using digital filters The following list gives some of the main advantages of digital over analog filters. 1. A digital filter is programmable, . its operation is determined by a program stored in the processor39。s are calculated from the x39。 this includes the ability of some types of digital filter to adapt to changes in the characteristics of the signa
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