Research on Wavelet De-noising for Bridge Alarming

The bridge damage alarming system mainly analysis the real-time monitoring signals, and judge bridge structure is damage or not, or the extent of damage. But signals gathered from sensors are affected by the noise inevitably. Signal quality is so important to the entire alarming system that noise must be removed before signals are processed. wavelet threshold value technology is adopted to carry out the multi-resolution analysis to received signals, Signals are decomposed into high and low frequency coefficients, high-frequency unit will be removed by using the wavelet threshold value, reconstruct the low-frequency unit and get the purpose of de-noising, different wavelet and wavelet threshold functions are selected to calculate the SNR, compare the different SNR values, the best wavelet, the best wavelet threshold selection criteria and the threshold of soft or hard functions will be got.