介绍了数字直接合成器 （DDS）、数字下变频器 （DDC）、数字滤波器等数字无线电经常用到的概念 。

We also introduced some concept of digital radio, including digital direction synthesizer (DDS) and digital down conversion (DDC) and digital filter.

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位于T形接合部上的L形带阻滤波器亦用来抑制第一谐振频率的倍频的谐振。

An L-shaped band elimination filter on the T-shaped joint part is also used for restricting the resonance of the frequency multiplication of the first resonance frequency.

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