The Design of Frequency Measure System Based on Microwave Resonator of Wetness Measurement

The resonant frequency of microwave resonator is deflection with the different permittivity. When wet steam pass the microwave resonator, we can get the permittivity of wet steam based the deflection of resonant frequency, according to the relation between permittivity and wetness, then we know the wetness of steam. So the precision of wetness measurement is directly depend the precision frequency of measurement. In this paper a new method of frequency measurement is introduced, which is multi-cycle synchronization combine the short time interval measurement. Under the control of the msp430 single chip, the function of equal precision in wide frequency range is carried out, removed plusmn1 counting error of the measured signal and the precision get to 10^-7, satisfy the requirement of wetness measurement.