| 摘要 |
A rate converter for digitally converting the sample rate of a signal, has a first digital filter for deriving an intermediate sig- nal at increased sample rate and a second digital filter for deriving an output signal at a decreased sample rate relative to that of the intermediate signal. The first filter is of relatively high order servin g to double the frequency. Because the frequency change is a power of two, the aperture characteristic is straightforward and implementation is simple even at high order. The second filter is of relatively low order so that implementation is simple even with a time- varying aperture characteristic. The low order of the sec- ond filter does not however degrade the overall frequency characteristic.</S DOAB>
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