Research And Design Of Ultrasonic Testing Data Compression Method

This dissertation mainly studies the ultrasonic testing system of ultrasonic testing data compression algorithm. Because the length of the test is long, the sampling frequency is very high, and the amount of data generated is very large, the storage space is far from satisfied. If the analysis data of the instrument in the detection device, the vast amounts of data there is no problem; if the instrument for data analysis does not in the field of ultrasonic testing, it is necessary to face transfer the data to an off-site analysis, data transmission becomes very serious problems, regardless of the data is wirelessly or through the Internet transmission,bandwidth is not able to load. Therefore, in order to meet the requirements of storage space and transmission bandwidth, simple and fast and efficient data compression algorithm is very important, and become an important technology to solve the problem of mass data processing of ultrasonic flaw detection.Aiming at this problem, this paper designs an efficient and fast compression algorithm by comparing and analyzing the characteristics of ultrasonic flaw detection data, and finally realizes and verifies its effectiveness. The waveform of ultrasonic data reflects the position of the defect. Lossy compression of data is likely to lose key information, resulting in very serious consequences, so it is necessary to carry out lossless compression, to prevent the loss of information. In this dissertation, a series of contrast and analysis, the final choice of the data preprocessing and Huffman coding compression of the two methods of data compression.Data preprocessing has become an important means to achieve high compression rate of data in recent years. There are many ways of data preprocessing, including data difference method, data filtering, etc., including lossy and lossless. The data preprocessing is waveform separation, by setting the cut-off value, the whole wave separated into defects waves and grass waves, the fluctuation range of the data change, for the Huffman coding compression.On the basis of pretreatment, from compression ratio, compression and decompression time and multiple data compression performance comparison of run length coding, Huffman coding, dictionary coding and arithmetic coding these four kinds of lossless compression algorithm, through comparative analysis to the final selection of Huffman coding compression as the core algorithm. Huffman coding is an efficient lossless compression algorithm, it is more simple, can achieve high compression ratio. The specific implementation,in the Visual Studio 2005 platform running program algorithm, the simulation is carried out.