数字锁相解调器的优化设计

数字锁相解调器是电磁无损检测中弱信号处理的重要方法，针对其性能优化，设计一种引入卡尔曼滤波器的数字锁相解调器，该解调器兼具了强抗噪能力及良好的动态跟踪响应特性。利用卡尔曼低通滤波器截止频率随迭代次数下降的特性，结合零点频率，设计了数字锁相解调器中的低通滤波环节，实现了非常窄的锁相带通，进而提高了抗击强噪声干扰能力。此外，利用卡尔曼滤波器的迭代预测-更新特点，实现了数字锁相解调器较小的响应时间，进而改善了数字锁相解调器的动态跟踪响应特性。仿真和检测实验证明所设计数字锁相解调器具有较高的抗噪能力和良好的动态跟踪响应特性，在电磁无损检测中能够精确、快速捕捉检测信号中包含的缺陷信息。 

Optimal design for digital phase-locked demodulator

Digital phase-locked demodulator is an important method for weak signal processing in electromagnetic non-destructive testing. For its performance optimization, a digital phase-locked demodulator with Kalman filter is designed, which has strong anti-noise ability and good dynamic tracking features. By using the characteristic that the cut-off frequency of Kalman low-pass filter decreases with the number of iterations and combining with the zero frequency, we design a low-pass filter in a digital phase-locked demodulator and then realize very narrow phase-locked bandpass, which improves the ability of strong noise resistance. In addition, using the predictive-update feature of the Kalman filter, the smaller response time of the digital phase-locked demodulator is realized, thereby improving the dynamic tracking characteristics of the digital phase-locked demodulator. Simulation and detection experiments show that the designed digital phase-locked demodulator has high noise immunity and good dynamic tracking response. It can accurately and quickly capture the defect information contained in the detection signal in electromagnetic non-destructive testing.