數(shù)字信號(hào)處理原理ppt課件-閱讀頁(yè)
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【正文】 ignal Processing Copyright 169。2022 by Pearson Education, Inc. Upper Saddle River, New Jersey 07458 All rights reserved. SAMPLING ? The sampling interval, or sampling period is the time in seconds between sampling points. ? The sampling frequency, or sampling rate, is the number of samples per second, measured in Hertz ? Relation: ss Tf1 i n t e r v a l S a m p l i n g1f r e q u e n c y S m p l i n g ??FIGURE 22 Analog signal. Joyce Van de Vegte Fundamentals of Digital Signal Processing Copyright 169。2022 by Pearson Education, Inc. Upper Saddle River, New Jersey 07458 All rights reserved. FIGURE 24 Digital signal (shown with sampleandhold signal). Joyce Van de Vegte Fundamentals of Digital Signal Processing Copyright 169。2022 by Pearson Education, Inc. Upper Saddle River, New Jersey 07458 All rights reserved. Nyquist Sampling theorem ? A signal with maximum frequency of W Hz must be sampled at least 2W times per seconds to make it possible to reconstruct the original signal being sampled. ? This minimum sampling frequency is called the Nyquist sampling rate. FIGURE 26 Aliasing in the time domain with 40 kHz sampling (adapted from Pohlmann, 1994). Joyce Van de Vegte Fundamentals of Digital Signal Processing Copyright 169。2022 by Pearson Education, Inc. Upper Saddle River, New Jersey 07458 All rights reserved. FIGURE 27 Antialiasing Filter. Joyce Van de Vegte Fundamentals of Digital Signal Processing Copyright 169。2022 by Pearson Education, Inc. Upper Saddle River, New Jersey 07458 All rights reserved. Quantization step ? N is the number of bits ? R is the full scale analog range ? The quantization step size is sometimes referred to as the resolution of the quantizer. ? Quantization error=Quantization valueActual value NRQ2?FIGURE 215 Quantization of unipolar data (maximum error = full step). Joyce Van de Vegte Fundamentals of Digital Signal Processing Copyright 169。2022 by Pearson Education, Inc. Upper Saddle River, New Jersey 07458 All rights reserved. Joyce Van de Vegte Fundamentals of Digital Signal Processing Copyright 169。2022 by Pearson Education, Inc. Upper Saddle River, New Jersey 07458 All rights reserved. FIGURE 219 Analogtodigital conversion. Joyce Van de Vegte Fundamentals of Digital Signal Processing Copyright 169。2022 by Pearson Education, Inc. Upper Saddle River, New Jersey 07458 All rights reserved. FIGURE 221 Threebit A/D conversion. Joyce Van de Vegte Fundamentals of Digital Signal Processing Copyright 169。2022 by Pearson Education, Inc. Upper Saddle River, New Jersey 07458 All rights reserved. FIGURE 223 Digitaltoanalog conversion. Joyce Van de Vegte Fundamentals of Digital Signal Processing Copyright 169。2022 by Pearson Education, Inc. Upper Saddle River, New Jersey 07458 All rights reserved. FIGURE 225 ThreeBit D/A conversion. Joyce Van de Vegte Fundamentals of Digital Signal Processing Copyright 169。2022 by Pearson Education, Inc. Upper Saddle River, New Jersey 07458 All rights reserved. FIGURE 226 Comparing signals in the A/D/D/A chain. Joyce Van de Vegte Fundamentals of Digital Signal Processing Copyright 169。2022 by Pearson Education, Inc. Upper Saddle River, New Jersey 07458 All rights reserved. FIGURE 226 Comparing signals in the A/D/D/A chain. Joyce Van de Vegte Fundamentals of Digital Signal Processing Copyright 1
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