frequency code频率码frequencyn.频繁；频率frequency-domain reflectometer频域反射器frequency modulated oscillations档振荡frequency regulation arrangement频率调节装置frequency-modulation reception调频接收frequency and response functions频响函数frequency equalization of speech语音频率均衡frequency-stepped chirp signal线性调频步进信号frequency modulation transmitter调频发射机Frequency Agile Signal Simulator频率捷变信号模拟装置frequency-modulation recording调频记录方法