载频调制二相编码激励的超声成像信噪比提高研究

摘要

针对压电陶瓷换能器的频带特性,采用正弦波载频调制二相编码信号的激励方案,研究换能器对单位码元载有不同周期载频的二相巴克码激励信号的影响,分析回波的脉冲压缩处理结果,优化调制参数,探讨激励信号与换能器的最佳匹配方式.利用本文提出的最佳调制参数的编码激励信号,在多目标环境下对四根靶线的复杂回波进行脉冲压缩实验研究,结果表明超声换能器对这种激励信号的响应及其回波的脉冲压缩效果理想,可以极大地提高超声检测的信噪比.%Considering the frequency spectrum of the piezoelectric ceramic transducer, this study uses a bi-phase coding signal modulated by a sine carrier as the excitation mode. Through using Barker code signal with each chip modulated by different periods of carrier, the transducer effect on the exciting signal and compression result is analyzed, modulation parameter is optimized, and the best matching mode between the exciting signal and the transducer is discussed. The echo of four target wires is processed by pulse compression with the optimum signal,the result shows that this excitation mode has a good performance on the transducer response, and it can enhance the SNR of the ultrasonic signal significantly.