This paper makes to level with the Numbers' translation theory, since know that ideal digital lowpassfilter directly gets method and the principle of needed digital system.
本文提出用数字平移理论，从己知理想数字低通的系统直接得到所需数字系统的原理和方法。
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In an extreme case, when the aliasing effects are very severe, using wiener filter can reduce the prediction errors'energy by about 50% in comparison with using the ideallowpassfilter.