中文摘要：

在蒸汽湿度测量系统中，为解决频率跟踪时延过长问题，提出了一种新的频率跟踪方法。根据微波谐振腔对不同频率输入信号的调制作用，通过鉴幅、鉴相判断输入信号频率与微波谐振腔谐振频率的关系，进而利用单片机控制压控振荡器（VCO）的输出频率，从而减小频率跟踪的时延，并实现频率跟踪的智能化。

英文摘要：

In the steam humidity measurement system, in order to salve the problem that the delay of frequency tracking isn＇t as short as we expected,this paper proposes a new kind of method for tracing frequency.According to the modulation of microwave cavity on different input signals,this paper judges the relationship between the frequency of input signal and the reso- nant frequency of microwave cavity through amplitude discrimination and phase demodulation,then,we use MCU to control the output frequency of VCO to minimize the delay of frequency tracking and realize the intelligence of frequency tracing.