说明：  直接数字频率合成（Direct Digital Fraquency Synthesis,即DDFS，一般简称DDS）是从相位概念出发直接合成所需要波形的一种新的频率合成技术。
(Direct Digital Synthesis (Direct Digital Fraquency Synthesis, that is, DDFS, generally referred to as DDS) is a departure from the concept phase direct synthesis of waveforms needed for a new frequency synthesis.)