短语词组短語frequency notch 陷頻現象;率凹口High frequency notch 高頻切跡frequency notch period 陷頻周期50Hz power frequency notch filter Hz 工頻陷波器frequency domain notch filter 頻域陷波器High Frequency SAW Notch Filter 高頻聲表麪波陷波器 返回 notch frequency