Lossless Audio Compressions Algorithms for Wireless Sensor Networks

• Main Authors: I-Ching Su, 蘇益清
• Other Authors: Mao-Ching Chiu
• Format: Others
• Language: zh-TW
• Published: 2014
• Online Access: http://ndltd.ncl.edu.tw/handle/38eycv

碩士 === 國立中正大學 === 通訊工程研究所 === 102 === This thesis is a research about wireless sensor networks in e-factories. The emphasis of this study is on how to apply lossless data compression algorithms on wireless sensor networks in e-factories. This research focuses primarily on detecting and processing audio signals generated by the rotation of machines in the factories in order to determine if machines are operating normally. In the development phase, a personal computer equipped with a data acquisition (DAQ) device is used as the platform to capture data. The source of the sensing signal is the sound emitted by machine while it is running. At the sensing terminal, programs written in C/C++ performs data capture and real-time compression algorithms; compressed data is then transmitted to a central control terminal through the wireless sensor network. At the central control terminal, data is reverted back to its original format using self-developed decompression algorithms for further processes. This study mainly investigates the actual applications of two different types of lossless data compression algorithms in compression systems. Comparisons of degrees of complexity and compression ratios between the two algorithms are made using the same audio signal source. The design of the compression algorithm employs normalized least mean square (NLMS) algorithm for prediction, and entropy codes including concatenated huffman codes and Rice Code.