The excitation frequency of radical solution in Overhauser magnetometer probe directly determines the quality of larmor precession signal

which is generated by the probe.In order to obtain the excitation frequency accurately

a test apparatus for measuring the excitation frequency of Overhauser magnetometer probe was designed.In view of the existing problems of present test apparatuses

such as lower resolution

complex operation and so on.This paper adopts a high-resolution DDS as the controllable RF signal source; using the ADC synchronization acquisition technology

combined with the data processing method of normalization

and the uneven problem of the amplitude-frequency characteristic curve in the range of 50MHz~100MHz has been solved effectively; moreover

by adopting the RF power amplifier

weak signal amplification as an auxiliary measurement channel

the apparatus's integration of standard measurement and aided measurement has been achieved.The equivalent circuit of the probe's resonant cavity is simulated

and the effect degree of the adjustable capacitor to the resonant frequency and quality factor of the Overhauser magnetometer probe is obtained.The simulated results are further verified by testing the curve of cavity resonance of the commercial probe under different parameters' conditions.Meanwhile

the relationship between the polarization degree of the radical solution and RF excitation power time are also obtained.The test method and results are given and the experimental data are analyzed.Finally

the experiment results demonstrate that the excitation frequency of the radical solution

excitation frequency bandwidth and quality factor can be found accurately by using this apparatus.And the apparatus can be also used for the determination of excitation power and excitation time in the process of magnetometer design

which lay the foundation for the design of Overhauser magnetometer in the future.