Through the adjustment of sound wave related parameter, we find the relationship of sound pressure, frequency and cleaning effect, and the best frequency.
调节声波相关参数，得出声波的频率和声压对清灰效果的影响关系，并找到最佳频率。
2
Direct digital synthesizer (DDS) is a kind of new frequency synthesizer technique. With it signal parameter can be switched into signal wave.
直接数字式频率合成(DDS)作为一种新的频率合成技术，它可以实现从信号参数到信号波形的转换。
3
After signal local wave decomposition, the information entropy according to time-frequency distribution was established, and it was used as characteristic parameter for fault recognition.