The transmitterof DHF uses DDS to synthesize frequency.

发射机采用直接数字频率合成器(DDS)生成频率,具有精度高、频率跳变速度快的特点.

Design History File ( DHF ) must be created for each type of device.

必须为每个设备型号建立设计历史文档.

A reusable draw help framework (DHF) is designed to implement the draw help function in CAD system.

从软件复用的角度设计了一个DHF，用来实现CAD系统中的绘图帮助功能。

Now these patients have beensystematically excluded from heart failure, named diastolic heart failure ( DHF ).

这些患者被从慢性心衰中分离出来, 称为舒张性心力衰竭 ( DHF ).