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脉冲压缩方法通过采用编码信号激励与脉冲压缩接收来提高超声检测的时间分辨率和信噪比。然而,受换能器带宽的限制,编码信号的时间带宽积往往有限,影响脉冲压缩效果。开展了基于超声阵列的多频脉冲压缩方法研究,超声阵列是由具有不同中心频率和带宽的多个阵元组成,从而使得整个阵列具有比单个换能器更宽的带宽。提出了压缩后叠加取包络的脉冲压缩方法,并研究了这种方法在提高时间分辨率和主副瓣比上的技术方案,对多频脉冲压缩的超声阵列进行了设计与优化,发现多频脉冲压缩方法能很大程度地提高时间分辨率,并能有效地抑制各阵元信号叠加产生的周期副瓣。理论和实验结果表明,这种压缩后叠加取包络的方法得到的时间分辨率在性能上受阵元带内不平整度的影响很小,能使阵元压缩包络中的主副瓣比得到明显改善。
The pulse compression method improves the time resolution and signal-to-noise ratio of ultrasonic detection by using coded signal excitation and pulse compression reception. However, limited by the bandwidth of the transducer, the time-bandwidth product of the encoded signal tends to be limited, affecting the pulse compression effect. A multi-frequency pulse compression method based on ultrasonic array is studied. The ultrasonic array consists of a plurality of array elements with different center frequencies and bandwidths, so that the whole array has a wider bandwidth than a single transducer. The pulse compression method of compressed superposition envelope is proposed, and the technical scheme of improving the time resolution and main / auxiliary ratio is studied. The multi-frequency pulse compression ultrasonic array is designed and optimized, and more The frequency pulse compression method can greatly improve the time resolution, and can effectively suppress the periodic sidelobe generated by the superposition of the signals of each array element. Theoretical and experimental results show that the time-resolution obtained by this method of compressing and stacking with envelope extraction is less affected by the unevenness of the band in the band, and the main and auxiliary sidelobe ratio Obvious improvement.