因此，采用AD器件和数字滤波器技术实现混频等频率变换功能，是一种比较先进和新颖并且实际可行的方法。

Therefore, taking advantage of AD device and digital filtering technique to realize mixing and other frequency transformation function is a comparatively advanced, novel and practical method.

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AB法是一种比较先进的监控方法，通过变换监控片和移动监控波长，把每层膜的镀制停点选择在灵敏位置。

AB method is much advanced in monitoring the thickness. Through the switch of monitoring glass and appropriate choice of wave length, stop point of each layer was located in sensitive position.

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