By analyzing the directfrequencymodulation and optical feedback effect of laser diode, a theoretical model for measuring small vibration displacement and velocity is discussed.
分析了在直接频率调制下，激光二极管中的光反馈效应，探讨了振动微小位移和速度的理论模型。
2
Direct digital synthesis (DDS) is an all digital frequency synthesis technique. Because of its special theory and construction, it has many kinds of modulation capability.
直接数字式频率合成(DDS)技术是一种全数字频率合成技术，其特殊的原理和结构使它具有多种调制能力。
3
The intrinsic frequency of a beaker can be determined by means of direct determination, resonance or water drip modulation, and each of the methods makes use of the Lissajous figure.