Abstract:The transmission characteristics and sine modulation characteristics were theoretically analyzed. In order to achieve track-locking of the resonance frequency, a test system of resonant frequency tracking and locking was designed and built. Sine wave modulation and demodulation were used to obtain the error signal of resonance frequency track-locking. Combining PID feedback control circuit with the error signal, the resonant frequency track-locking was realized, and further the accuracy and stability of the resonant frequency track-locking were assessed.