Abstract
Due to the engineering demand of oil and gas pipeline crack inspection, a new ultrasonic method based on non-contact ultrasonic transducer known as EMAT has emerged. Because of the large amount of original waveform data and limited speed and capacity of storing device, research on online data compression is needed. A subsection adaptive compression algorithm based on the features of the inspection data is proposed. The compression precision can be adjusted by altering compression threshold. Compression experiments of 250 kHz EMAT guided wave data are conducted using this algorithm. The results indicate that the algorithm has good quality, and can achieve rather high compression ratio at the same time. A compression ratio around 20:1 can be achieved on sample data. Compression quality evaluation is performed using error sequence and PSNR.
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