超声波测振信号的能量算子解调方法

Energy Operator Demodulation Method of the Ultrasonic Vibration Measurement Signal

连续超声波束遇到振动物体表面会产生多普勒效应,反射超声波信号是受振动信号调制的非线性调相信号。对反射波信号求导获得调幅调频信号,再采用能量算子对称差分法,求取该调幅调频信号的瞬时幅值及瞬时频率。鉴于超声波反射回波信号存在幅值衰减现象,而超声波频率不易受外界干扰,故通过调幅调频信号的瞬时频率提取被测物体的振动速度,并由振动速度求导得到振动加速度。同时,从幅值及频率两个方面探讨振动测量范围。仿真及实验结果表明:基于能量算子的超声波测振信号解调方法能有效地提取振动信号,与传统的相位解调方法相比,具有更大的测量范围。

A continuous ultrasonic beam is emitted towards the moving surface and the received ultrasound signal isphase modulated by vibration signal due to the Doppler Effect. The AM-FM signal is derieved from the derivative of thereceived ultrasound signal. The instantaneous frequency and instantaneous amplitude of the AM-FM signal are obtainedthrough symmetrical difference of the energy operator demodulation. The amplitude attenuation of the received ultrasoundsignal is inevitable, but its frequency is not susceptible to external interference. So, the vibration speed of the object can beobtained from the instantaneous frequency of the AM-FM signal, and the vibration acceleration can be obtained from thederivative of the vibration velocity. The range of vibration measurement is discussed from the viewpoints of amplitude andfrequency. Simulation and experiment results show that the energy operator demodulation method for the ultrasonicvibration measurement signal can effectively extract the vibration signal and this method has larger measurement range thanthe traditional phase demodulation method.