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电磁超声是管道裂纹检测的有效手段,由于原始波形的数据量很大,而检测器存储设备的容量和存储速度相对有限,有必要研究检测数据在线压缩算法。文中分析了管道检测的特殊环境及其对数据压缩的要求,针对检测器系统的特点及检测数据的特征,提出了分段自适应压缩算法。该算法能够根据信号的幅值变化实时改变压缩比,并且可以通过改变压缩阈值的方法来调整压缩的精度。实验结果显示:该算法应用在电磁超声导波波形数据上,有着较为理想的波形保真度,同时达到了较高的压缩比。对算法优缺点的分析和对压缩质量的评估结果表明:分段自适应压缩算法在压缩效率,压缩质量和算法复杂度等多方面均满足管道电磁超声检测大量数据压缩的要求。
Electromagnetic ultrasound is an effective method for pipeline crack detection. Because of the large amount of data of the original waveform and the limited storage capacity and storage speed of the detector storage device, it is necessary to study on-line compression algorithm of detection data. In this paper, the special environment of pipeline inspection and its requirements for data compression are analyzed. Aiming at the characteristics of detector system and the characteristics of detection data, a subsection adaptive compression algorithm is proposed. The algorithm can change the compression ratio in real time according to the amplitude change of the signal, and can adjust the compression precision by changing the compression threshold. The experimental results show that the proposed algorithm has good waveform fidelity and high compression ratio at the same time, which is applied to electromagnetic ultrasonic guided wave data. The analysis of the advantages and disadvantages of the algorithm and the evaluation of the compression quality show that the sub-band adaptive compression algorithm meets the requirements of massive data compression in the pipeline electromagnetic ultrasonic detection in terms of compression efficiency, compression quality and algorithm complexity.