frequency lead频率导引frequencyn.频繁；频率frequency-division multiplex access频分多址frequency modulation signal generator调频信号发生器Frequency - hopping Spread Spectrum跳频Frequency converter with high voltage高压变频装置frequency-selective level indicator选频式电平表Frequency conversion speed adjustment变频调速Frequency response curve of regulator调节器频率特性曲线frequency electric and magnetic field工频电磁场frequency conversion timing technique变频调速技术Frequency and phase angle measurement频率相位测量