Study Of Cab Signal Data Compression Method For Storage Based On Wavelet Analysis

At present, in the background of railway development and continuous extension of cross road, the uncompressed data recording method of cab signal can not meet the needs of practical application. The waveform data which hold a large proportion in cab signal data is the important basis of cab signal and track circuit fault diagnosis. Therefore, to study data compression method which meets the practical application requirements of cab signal has important significance and practical value.At the basis of deep study of wavelt analysis theory and using domestic frequency shift and ZPW-2000A signal as main research object, the paper proposes a method of cab signal waveform data compression using wavelet packet. The main research work in this thesis is as follows:1. A waveform data compression algorithm using Dmey orthogonal wavelet packet is proposed. At first, according to Mallat algorithm of orthogonal wavelet packet, the waveform data is decomposed by using the QMF filter, and then through theoretical analysis and lab simulation, the wavelet base function is determined to be Dmey and the decomposition level is set to 3-4. Second, the frequency band distribution result at each level are obtained by using binary coding of wavelet packet QMF filter path. At last, according to the energy distribution of the signal, combining wih the frequency band distribution result and amplitude-frequency characteristics of wavelet packet QMF filter, the wavelet packet decomposition binary tree of waveform data is pruned, as a result, only the nodes which are in the frequency bands are saved, so the waveform data compression is achieved.2. The test set of algorithm is built using lab simulation data and the actual waveform data in the cab signal ground data processing system. And the compression performance is tested using the set, the correctness and effectiveness of the algorithm is verified too. The simulation results show that higher compression ratio and compression accuracy can be obtained by using the compression method of cab signal waveform data proposed by the paper, and the method has better applicability and flexibility, meanwhile a less waveform distortion can also been got.3. The cab signal recorder waveform data ground decompression software are programmed using Matlab GUI technology. The software realizes the function of decompressing the waveform data which compressed in the onboard equipment of cab signal. The test result shows that the software is simple to use and has a fast computing speed, it also has a high-quality interface.